METHOD AND APPARATUS FOR ZONAL ISOLATION OF SUBTERRANEAN FORMATIONS USING SET-ON-DEMAND SLURRIES

Abstract

Methods are disclosed for providing zonal isolation of subterranian formations. One embodiment may include mixing a dry blended material with water at a central location to create a suspension, transferring the suspension to one or more storage tanks at the central location, transferring the suspension to one or more storage tanks at a rig site, recirculating the suspension in the one or more storage tanks at the rig site, and pumping the suspension into a well. Another embodiment may include mixing a dry blended material with water in one or more storage tanks at a rig site to create a suspension, recirculating the suspension in the one or more storage tanks at the rig site, and pumping the suspension into a well.

Description

BACKGROUND

The present disclosure relates generally to well drilling operations and, more particularly, to a method and apparatus for providing zonal isolation of subterranean formations.

After a well bore for the production of hydrocarbons has been drilled, a casing string may be lowered and cemented therein. In typical cementing operations, a desired amount of a cement slurry may be directed downhole through the casing string, out of the bottom of the casing string, and up through the annulus between the casing string and the well bore wall (or a casing if the well bore is cased), to cement the casing string in place. Alternatively, in certain implementations, the casing may be cemented into the well bore by utilizing what is known as a “reverse-cementing” method. Reverse-cementing entails displacing a conventionally mixed cement slurry into the annulus between the casing string and the well bore wall (or a casing if the well bore is cased). As cement is pumped down the annular space, drilling fluids ahead of the cement are displaced around the lower ends of the casing string and up through the casing string and out at the surface. The fluids ahead of the cement may also be displaced upwardly through a work string that has been run into the inner diameter of the casing string and sealed off at its lower end. To ensure that a good quality cement job has been performed, a small amount of cement may be permitted into the casing and the work string. As soon as a desired amount of cement has been pumped into the annulus, the work string may be pulled out of its seal receptacle and excess cement that has entered the work string can be reverse-circulated out of the lower end of the work string to the surface.

The equipment required for performing cementing operations is typically transported to the worksite using one or more tractor-trailers. Since the operation of tractor-trailers is highly regulated, the cementing operations are also controlled by corresponding regulations. Compliance with these regulations may lead to delay in operations and increased costs. For example, a regulation may limit the number of hours a driver may drive, preventing the driver from continuing operations if the driver used all the allowed hours in getting to the worksite and setting up. Because time is often critical in these operations, another worker must be present to do work that the driver could otherwise do, since a cementer may also have the ability to drive the tractor-trailer. Tractor-trailers are also limited by terrain and may not be able to get to or enter certain worksites without suitable roads first being built, which may be a costly endeavor.

In current cementing applications, the equipment that is required at the rig location may include: one or two cementing trailers; multiple bulk trailers, depending on size of job; and possibly a batch mixing trailer. The cementing trailer may incorporate the cement mixer and high pressure pump for mixing the water and dry bulk material into a cement slurry and then may pump this slurry to the well. The bulk trailer is used to transport the dry bulk material to the rig location. This bulk trailer incorporates bulk tanks and an air compressor that will move the dry bulk material to a cementing trailer. Some jobs require a batch mixing trailer, used to provide a better uniform slurry. In current cementing applications, five to seven separate pieces of equipment may be required.

In current cementing applications, the quality of the cement slurry is determined by the density of the slurry on the fly during the mixing operation. The mix-on-the-fly nature of the operation relies heavily on the quality of the operators, equipment, chemical design, and uniformity of blend during preparation and transporation to a well site to determine cement quality.

FIGURES

Some specific exemplary embodiments of the disclosure may be understood by referring, in part, to the following description and the accompanying drawings.

FIG. 1A is a flowchart depicting a method of providing zonal isolation of subterranean formations according to embodiments of the present disclosure, where mixing occurs at a central location.

FIG. 1B is a flowchart depicting a method of providing zonal isolation of subterranean formations according to embodiments of the present disclosure, where mixing occurs at the rig site.

FIG. 2 depicts a Smart Tank System for the storage of well bore slurries in accordance with embodiments of the present disclosure.

FIG. 3A illustrates a side view of the Smart Tank System of FIG. 2 with a recirculation system according to embodiments of the present disclosure.

FIG. 3B illustrates an overhead view of the Smart Tank System of FIG. 2 according to embodiments of the present disclosure.

While embodiments of this disclosure have been depicted and described and are defined by reference to exemplary embodiments, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.

DETAILED DESCRIPTION

The present disclosure relates generally to well drilling operations and, more particularly, to a method and apparatus for providing zonal isolation of subterranean formations.

Illustrative embodiments of the present disclosure are described in detail herein. In the interest of clarity, not all features of an actual implementation may be described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the specific implementation goals, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of the present disclosure.

For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU), hardware or software control logic, Programmable Logic Controller (PLC), Read-Only Memory (ROM), and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communication with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components.

The terms “couple” or “couples” as used herein are intended to mean either an indirect or a direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect mechanical or electrical connection via other devices and connections. The term “uphole” as used herein means along the drillstring or the hole from the distal end towards the surface, and “downhole” as used herein means along the drillstring or the hole from the surface towards the distal end.

To facilitate a better understanding of the present disclosure, the following examples of certain embodiments are given. In no way should the following examples be read to limit, or define, the scope of the disclosure. Embodiments of the present disclosure may be applicable to horizontal, vertical, deviated, multilateral, u-tube connection, intersection, bypass (drill around a mid-depth stuck fish and back into the well below), or otherwise nonlinear wellbores in any type of subterranean formation. Embodiments may be applicable to injection wells, and production wells, including natural resource production wells such as hydrogen sulfide, hydrocarbons or geothermal wells; as well as borehole construction for river crossing tunneling and other such tunneling boreholes for near-surface construction purposes or borehole u-tube pipelines used for the transportation of fluids such as hydrocarbons. Embodiments described below with respect to illustrative implementations are not intended to be limiting.

According to aspects of the present disclosure, a method and apparatus for providing zonal isolation of subterranean formations is disclosed herein. Referring to FIG. 1A, general method steps in accordance with a first exemplary embodiment of the present disclosure are denoted with reference numeral 100. Although a number of steps are depicted in FIG. 1A, as would be appreciated by those of ordinary skill in the art, having the benefit of the present disclosure, one or more of the recited steps may be eliminated or modified without departing from the scope of the present disclosure. In addition, additional steps may be added without departing from the scope of the present disclosure.

At step 102, the method may include mixing a blend of dry ingredients at a central location. The central location may be a service center, a dry blending plant, or any other suitable location for mixing the blend of dry ingredients. As would be appreciated by one of ordinary skill in the art with the benefit of this disclosure, any suitable mixing/blending system may be utilized to mix the blend of dry ingredients at the central location, including, but not limited to, a blend tank, storage tank, scale tank, or any other stationary tank and interconnected manifolds. A pressurized bulk system or a vacuum bulk system also may be used. The blend of dry ingredients may be any delayed hydrating cement that can be stored for extended periods before being pumped into a well bore. The dry mixture may be stored in dry bulk form.

At step 104, the dry blended material may be mixed with a desired amount of water and/or any additional liquid additives to form a consistent and stable suspension. The suspension may comprise, and be referred to herein as, an Extended Life Suspension (“ELS”). In this mixing process, various mixing apparatuses can be used. For example, these apparatuses may be centrifugal pumps, eductors, hoppers, nozzle jets, and agitators. In certain embodiments, the ratio of water to dry blend may range from 50% to 70% by weight of the blend. One embodiment of this mixing process may include mixing the ELS with a common cement mixing unit, then pumping the ELS into a Smart Tank System (STS) 200 at the central location for storage using a centrifugal pump 210. In another embodiment, a mixing device on the STS 200 would mix the dry blended material with a desired amount of water and/or liquid additives and discharge the ELS directly into the tanks on the STS 200. In another embodiment, the ELS slurry is mixed and discharged into any tank suitable for containing the ELS slurry material.

The dry blend may be mixed with water containing dispersants, retarders, de-foamers, fluid loss agents, viscosifiers, lost circulation agents, elastomers, weighting agents, and other additives recognized as necessary by those skilled in the art of cementing. A typical cement slurry will hydrate and set within hours of being mixed with water whereas the ELS slurry may be stored in the liquid state for days or weeks.

In certain embodiments, the methods of the present invention may be used in conjunction with certain set-delayed cement compositions as the suspension or ELS. For example, a set-delayed cement composition is disclosed in U.S. patent application Ser. No. 13/417,001 entitled “Set-Delayed Cement Compositions Comprising Pumice and Associated Methods” and assigned to Halliburton Energy Services, Inc., which is incorporated herein by reference in its entirety. Embodiments of the set-delayed cement compositions useful in the present disclosure as the disclosed ELS may generally comprise water, pumice, hydrated lime, and a set retarder. Optionally, the ELS may further comprise a dispersant. Embodiments of the ELS may be capable of remaining in a pumpable fluid state for an extended period of time. For example, the ELS may remain in a pumpable fluid state for approximately one day or longer.

In certain implementations the ELS may comprise pumice. Generally, pumice is a volcanic rock that can exhibit cementitious properties, in that it may set and harden in the presence of hydrated lime and water. The pumice may also be ground, for example. Generally, the pumice may have any particle size distribution as desired for a particular application. In certain embodiments, the pumice may have a mean particle size in a range of from approximately 1 micron to approximately 200 microns. An example of a suitable pumice is available from Hess Pumice Products, Inc., Malad, Id., as DS-325 lightweight aggregate, having an average particle size of less than 15 microns. It should be appreciated that particle sizes too small may have mixability problems while particle sizes too large may not be effectively suspended in the compositions. One of ordinary skill in the art, with the benefit of this disclosure, should be able to select a particle size for the pumice suitable for use for a chosen application.

In certain implementations, the ELS may comprise hydrated lime. As used herein, the term “hydrated lime” refers to calcium hydroxide. The hydrated lime may be included in embodiments of the ELS, for example, to form a hydraulic composition with the pumice. For example, in certain implementations the hydrated lime may be included in a pumice-to-hydrated-lime weight ratio of approximately about 10:1 to approximately about 1:1. In certain embodiments, the hydrated lime may be included in a pumice-to-hydrated-lime weight ratio of approximately about 3:1 to approximately about 5:1. Where present, the hydrated lime may be included in the ELS in an amount in the range of from approximately 10% to approximately 100% by weight of the pumice, for example. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of the hydrated lime to include for a chosen application.

The water used in embodiments of the ELS useful in the present disclosure may be from any source provided that does not contain an excess of compounds that may undesirably effect other components in the ELS. For example, a set-delayed cement composition may comprise fresh water or salt water. Salt water generally may include one or more dissolved salts therein and may be saturated or unsaturated as desired for a particular application. Seawater or brines may be suitable for use in embodiments of the present invention. Further, the water may be present in an amount sufficient to form a pumpable slurry. In certain embodiments, the water may be present in the set-delayed cement composition in an amount in the range of from approximaely 33% to approximately 200% by weight of the pumice. In certain embodiments, the water may be present in the set-delayed cement compositions in an amount in the range of from approximately 35% to approximately 70% by weight of the pumice. One of ordinary skill in the art with the benefit of this disclosure will recognize the appropriate amount of water for a chosen application.

Embodiments of the ELS may comprise a set retarder. A broad variety of set retarders may be suitable for use in the ELS useful in the present invention. For example, the set retarder may comprise phosphonic acid, phosphonic acid derivatives, lignosulfonates, salts, organic acids, carboxymethylated hydroxyethylated celluloses, synthetic co- or ter-polymers comprising sulfonate and carboxylic acid groups, borate compounds, derivatives thereof, or mixtures thereof In certain embodiments, the set retarders used in the ELS useful in the present invention are phosphonic acid derivatives, such as those described in U.S. Pat. No. 4,676,832, the disclosure of which is incorporated herein by reference. Examples of suitable set retarders include, among others, phosphonic acid derivatives available from Halliburton Energy Services, Inc., of Duncan, Okla., as Micro Matrix® cement retarder.

As previously mentioned, embodiments of the ELS may optionally comprise a dispersant. Examples of suitable dispersants include, without limitation, sulfonated-formaldehyde-based dispersants and polycarboxylated ether dispersants. One example of a suitable sulfonated-formaldehyde-based dispersant that may be suitable is a sulfonated acetone formaldehyde condensate, available from Halliburton Energy Services, Inc., of Duncan, Okla. as CFR™-3 dispersant. One example of a suitable polycarboxylated ether dispersant that may be suitable is Liquiment® 514L dispersant, available from BASF Corporation, Houston, Tex., that comprises 36% by weight of the polycarboxylated ether in water. In certain embodiments, the ELS may include one or more of a viscosifier, a fluid loss agent, a lost circulation agent, an elastomer, and a weighting agent. Example of the additives available for use in certain embodiments are provided for illustrative purposes only and are not intended to limit the invention. The viscosifier may be SA-1015™, WG-17™, Biozan®, or any other similarly suitable compund. The fluid loss agent may be Halad-344, Halad-447, Latex 3000, or any other similarly suitable compound. The lost circulation agent may be Flocele, Pol-e-flake, or any other similarly suitable compound. The elastomer may be WellLife additives, ground rubber tire, or any other similarly suitable compound. The Weighting agent may be Hi Dense-4, Barite, MicroMax, or any other similarly suitable compound.

At step 106, the ELS may be stored at the central location in ELS storage tanks 220 on the STS 200 for an extended period of time. For example, the STS 200 may allow storage of ELS for thirty days. During storage, the ELS may continue to remain in a pumpable and stirable fluid state without substantial gelling or changes in viscosity.

At step 108, multiple samples of the ELS may be obtained for quality control testing and batch lot retention. The methods used to obtain such samples are well known to those of ordinary skill in the art and will therefore not be discussed in detail herein. In certain implementations, laboratory testing may be performed to certify performance of the ELS. For example, possible tests include measuring compressive strength, static gel strength, transistion time, thickening time, viscosity, mechanical properties when set, and fluid loss of the ELS. In response to laboratory test results, additional additives may be added to the ELS in order to adjust or maintain desired chemical, rheological, shear, and fluid loss properties.

At step 110, the ELS may be recirculated and/or stirred during storage at the central location. In certain embodiments, recirculation may be accomplished by opening a valve on the bottom of the STS tank 220 and using a centrifugal pump 210, for example, to recirculate the ELS back to the top of the tank thus “rolling” the tank. The tanks may also have agitators to “stir” the ELS material in the tanks. The “rolling” and/or “stirring” of the tank may happen all the time or at such intervals, for example, once a day, in order to keep the ELS slurry in a stirable and pumpable condition.

At step 112, the ELS may be transported to the rig site using liquid storage trailers common to oilfield use and known to one of ordinary skill in the art. The liquid storage trailers can come in various shapes and sizes, for example, horizontal cylindrical trailers. At the rig site, the ELS may be transferred to a second STS 200 at the rig site, where the STS 200 at the rig site may be previously set up on site at the convenience of rig and service personnel. Liquid accelerator may be transported and transferred to an accelerator tank 230 on the STS 200 at the rig site. There may be more than one STS 200 on site, depending on the amount of ELS required for the particular well.

At step 114, the ELS may be tested or sampled by sensors (not shown) on the STS 200 at the rig site. For example, the sensors may include temperature sensors, density measurement sensors, viscosity measuring devices, level sensors, and any other sensors to measure desired properties of the ELS. In response to the measured properties, additional additives may be added to the ELS in order to adjust or maintain desired chemical, rheological, shear, and fluid loss properties.

At step 116, the ELS may continue to be recirculated or mixed in the STS 200 at the rig site. In certain embodiments, recirculation may be accomplished by opening a valve on the bottom of the STS tank 220 and using a centrifugal pump 330, for example, to recirculate the ELS back to the top of the tank thus “rolling” the tank. The tanks may also have agitators to “stir” the ELS material in the tanks. The “rolling” and/or “stirring” of the tank may happen all the time or at such intervals, for example, once a day, in order to keep the ELS slurry in a stirable and pumpable condition.

At step 118, the ELS may be mixed with an accelerator to cause the ELS to set after it is placed in the well bore. In certain embodiments, the accelerator may be stored in an accelerator tank 230 located on the STS 200. In certain embodiments, the accelerator may be liquid and may be metered with a liquid additive system designed to meter liquids to a predetermined set point. In certain embodiments, the accelerator may be dry and may be added to the ELS during circulation prior to pumping the ELS into the well bore.

At step 119, in certain embodiments, one or more additives may be added to adjust the density and/or viscosity of the ELS. The additives may include one or more of a set retarder, a dispersant, a viscosifier, a fluid loss agent, a lost circulation agent, an elastomer, and a weighting agent, as discussed above. In certain embodiments, the additive may be added along with accelerator to adjust the density and/or viscosity of the ELS.

At step 120, the ELS may be foamed using the nitrogen gas foaming process known by one of ordinary skill in the art. A nitrogen truck and pumping unit may pump compressed nitrogen gas at a desired temperature, pressure, and rate to foam the ELS with accelerator and/or water to obtain a desired density level. The nitrogen gas may be pumped to a foam generator to mix the nitrogen gas with a liquid stream in order to foam the liquid stream.

At step 122, the ELS may be pumped into a wellbore. In certain embodiments, the accelerator may be added while the ELS is being pumped into the wellbore. This may be accomplished by using a computer system to control the ratio of the accelerator at a predetermined percentage of the ELS slurry. For example, the accelerator may need to be at 5% to 15% by weight and/or by volume of the ratio to the ELS slurry. A separate pump and control system may be used to add the accelerator into the stream of ELS to be pumped downhole.

While steps 102, 104, 106, 108, 110, 112, 114 and 116 are described in a particular order, these steps may be performed in a different order, or two or more of those steps may be performed substantially simultaneously (e.g., in real-time) with each other without departing from the scope of the present disclosure. Further, as would be appreciated by those of ordinary skill in the art, one or more method steps may be added or eliminated without departing from the scope of the present disclosure.

Referring now to FIG. 1B, general method steps in accordance with another illustrative embodiment of the present disclosure are denoted with reference numeral 150. Although a number of steps are depicted in FIG. 1B, as would be appreciated by those of ordinary skill in the art, having the benefit of the present disclosure, one or more of the recited steps may be eliminated or modified without departing from the scope of the present disclosure. In addition, additional steps may be added without departing from the scope of the present disclosure.

First, at step 152, the method may include mixing a blend of dry ingredients at a central location. The central location may be a service center, a dry blending plant, or any other suitable location for mixing the blend of dry ingredients. As would be appreciated by one of ordinary skill in the art with the benefit of this disclosure, any suitable mixing/blending system may be utilized to mix the blend of dry ingredients at the central location, including, but not limited to, a blend tank, storage tank, scale tank, or any other stationary tank and interconnected manifolds. A pressurized bulk system or a vacuum bulk system may also be used. The blend of dry ingredients may be any delayed hydrating cement that can be stored for extended periods before being pumped into a well bore. The dry mixture may be stored in dry bulk form.

At Step 153, the dry blended material may be transferred to a dry bulk transport truck/trailer to be transported to the rig site. The bulk transport truck/trailer is recognized by those skilled in the oil field industry, for example, some have two 330-cubic-foot tanks for a total of 660 cubic feet of dry material that can be driven to the rig site. As would be appreciated by one of ordinary skill in the art, once at the rig site the bulk transport truck/trailer may be pressurized so that the dry blended material can be “blown” to a mixer at the rig site.

At step 154, the dry blended material may be mixed with a desired amount of water and/or any additional liquid additives at the rig site to form a consistent and stable suspension or ELS. As discussed above in step 104, this mixing process, may use various mixing apparatuses. For example, these apparatuses may be centrifugal pumps, eductors, hoppers, nozzle jets, and agitators. In certain embodiments, the ratio of water to dry blend may range from approximately 50% to approximately 70% by weight of the blend. In certain implementations, the mixing process may include mixing the ELS with a common cement mixing unit, then pumping the ELS into an STS 200 for storage using a centrifugal pump 210. In another embodiment, a mixing device on the STS 200 may mix the dry blended material with a desired amount of water and/or liquid additives and discharge the ELS directly into the tanks on the STS 200. In another embodiment, after the ELS slurry is mixed it may be discharged into any tank suitable for containing the ELS slurry material. The dry blend may be mixed with water containing dispersants, retarders, de-foamers, fluid loss additives, elastomers (liquid and/or dry), weighting agents (light weight and/or heavy weight), and other additives recognized as necessary by those skilled in the art of cementing. A typical cement slurry will hydrate and set within hours of being mixed with water whereas the ELS slurry may be stored in the liquid state for days or weeks.

At step 156, the ELS may be stored at the rig site in ELS storage tanks 220 on the STS 200 for an extended period of time. For instance, in certain embodiments, the STS 200 may allow storage of ELS for thirty days. During storage, the ELS may continue to remain in a pumpable and stirable fluid state without substantial gelling or changes in viscosity.

At step 158, one or more samples of the ELS may be obtained at the rig site for quality control testing and batch lot retention. The methods used to obtain such samples are well known to those of ordinary skill in the art and will therefore not be discussed in detail herein. In certain implementations, laboratory testing may be performed to certify performance of the ELS. For example, possible tests include measuring compressive strength, thickening time, viscosity, and fluid loss of the ELS. In response to laboratory test results, additional additives may be added to the ELS in order to adjust or maintain desired chemical, rheological, shear, and fluid loss properties.

At step 160, the ELS may be recirculated and/or stirred during storage at the rig site. In certain embodiments, recirculation may be accomplished by opening a valve on the bottom of the STS tank 220 and using a centrifugal pump 210, for example, to recirculate the ELS back to the top of the tank thus “rolling” the tank. The tanks may also have agitators to “stir” the ELS material in the tanks. The “rolling” and/or “stirring” of the tank may happen all the time or at such intervals, for example once a day, in order to keep the ELS slurry in a stirable and pumpable condition.

At step 162, the ELS may be mixed with an accelerator to activate the ELS and cause the ELS to set after it is placed in the well bore. In certain embodiments, the accelerator may be stored in an accelerator tank 230 located on the STS 200. In certain embodiments, the accelerator may be liquid and may be metered with a liquid additive system designed to meter liquids to a predetermined set point. In certain embodiments, the accelerator may be dry and may be added to the ELS during circulation prior to pumping the ELS into the well bore.

At step 163, in certain embodiments, one or more additives may be added to adjust the density and/or viscosity of the ELS. The additives may include one or more of a set retarder, a dispersant, a viscosifier, a fluid loss agent, a lost circulation agent, an elastomer, and a weighting agent, as discussed above. In certain embodiments, the additive may be added along with accelerator to adjust the density and/or viscosity of the ELS.

At step 164, the ELS may be foamed using the nitrogen gas foaming process known by one of ordinary skill in the art. A nitrogen truck and pumping unit may pump compressed nitrogen gas at a desired temperature, pressure, and rate to foam the ELS with accelerator and/or water to obtain a desired density level. The nitrogen gas may be pumped to a foam generator to mix the nitrogen gas with a liquid stream in order to foam the liquid stream.

At step 166, the ELS may be pumped into a wellbore. In certain embodiments, the accelerator may be added while the ELS is being pumped into the wellbore. This may be accomplished by using a computer system to control the ratio of the accelerator at a predetermined percentage of the ELS slurry. For example, the accelerator may need to be at 5% to 15% of the ratio to the ELS slurry, by weight. In another example, the accelerator may be at 5% to 15% of the ratio to the ELS slurry, by volume. A separate pump and control system may be used to add the accelerator into the stream of ELS to be pumped downhole.

While steps 152, 153, 154, 156, 158, 160, and 162 are described in a particular order, these steps may be performed in a different order, or two or more of those steps may be performed substantially simultaneously (e.g., in real-time) with each other without departing from the scope of the present disclosure.

Referring to FIG. 2, the details of configuration and operation of the STS 200 will now be discussed. The STS 200 may include multiple suspension storage tanks, referred to herein as ELS storage tanks 220. Each of the ELS storage tanks 220 may have a shape and size that is suitable for the particular application. For instance, in certain implementations, one or more of the ELS storage tanks 220 may be cone bottom tanks. In certain embodiments, the ELS storage tanks 220 may have curved bottoms (flanged and dished heads), slanted bottoms, or other types of bottoms that allow for adequate draining of the ELS. In certain embodiments, each ELS storage tank 220 may have a capacity of approximately 50 to 80 barrels. In certain embodiments, the cone bottom tanks may be arranged on a platform 240. The platform 240 may be moveable to facilitate movement of the STS 200 from one desired location to another. For instance, in certain implementations, the platform 240 may be a mobile semi-trailer. Configuration of the platform 240 in this manner is well known to those of ordinary skill in the art, having the benefit of the present disclosure, and will therefore not be discussed in detail herein.

FIGS. 3A and 3B illustrate an exemplary ELS storage tank 220 equipped with a recirculation system 310, which may be used in conjunction with the STS 200 of the present disclosure, particularly with respect to step 110, and 116, in FIG. 1A and step 160 in FIG. 1B. In certain illustrative embodiments, the recirculation system 310 may include an internal mixing device 320 and/or a cone bottom return jet 340. The internal mixing device 320 may be any suitable mixing device known to those of ordinary skill in the art. For instance, in certain implementations, the internal mixing device 320 may include, but is not limited to, gate impellers, anchor impellers, double helix impellers, agitators, or any other suitable mixing device. In certain implementations, the internal mixing device 320 may include at least one mixing blade. As an example, the recirculation system 310 may recirculate at least two tank volumes of ELS per day. In certain embodiments, a centrifugal pump 330 may pump the ELS through the cone bottom return jet 340 to maintain the ELS as a substantially homogeneous fluid and to assist in homogenizing the ELS when adding dry or liquid materials. In addition, the ELS mixture may be agitated once a day with an internal mixing device 320. In certain embodiments the agitators may be paddles as known to those of ordinary skill in the art.

The ELS may continue to be recirculated or mixed in the STS at the rig site, particularly with respect to step 116 in FIG. 1A or 160 in FIG. 1B. This continued recirculation and/or mixing at the rig site may be similar to recirculation described with respect to step 110. The ELS can continue to be recirculated and/or mixed for multiple days, depending on the rig schedule or complications that may arise delaying the cement job. The ELS may be stored to be ready for immediate cementing when the rig is ready for the cement job.

The internal mixing device 320 and the cone bottom return jet 340 may ensure adequate mixing of fluids during recirculation. The STS 200 may include at least one recirculation nozzle 350 to allow the ELS to recirculate. In certain embodiments, the STS 200 includes three recirculation nozzles 350A, 350B, 350C. The recirculation nozzles 350 may be located in the lower third of the tank height. For example, a recirculation nozzle 350 may be placed just above where the cone bottom 360 meets the vertical tank wall 370. The recirculation nozzles 350 may be oriented to optimize recirculation of the ELS. For example, in certain illustrative embodiments, the first nozzle 350A may be set at substantially zero degrees from horizontal, the second nozzle 350B may be set at substantially forty-five degrees downward from horizontal, and the third nozzle 350C may be set at substantially ninety degrees downward from horizontal.

Referring again to FIG. 2, in certain embodiments, the STS 200 may include a control system 250 to monitor and regulate the tank's operation. This control system 250 may include, but is not limited to, one or more recirculation pumps to recirculate the mixture; density meter to determine density; a flowmeter to monitor fluid flow rate; temperature probes to monitor temperature; pressure transducers to monitor pressure; weight load cells to monitor weight; and a process control system for controlling the STS 200.

Additionally, the STS 200 may be configured to communicate with a remote information handling system through a wired or wireless communication network using a communication device 260. Implementation of such wired or wireless communication networks is well known to those of ordinary skill in the art, having the benefit of the present disclosure and will therefore not be discussed in detail herein. The information handling system may transmit and receive signals from the STS 200. For instance, the information handling system may transmit signals to control various operations being performed by the STS 200 or it may receive signals from one or more sensors of the STS 200 to monitor operations.

In certain implementations, the communication device 260 may be a satellite dish to communicate with the information handling system. The communication network between the tank and the remote information handling system may facilitate a remote control system allowing pumps to be operated and instrument readings to be transmitted to a remote location using the communication device 260. The control system 250 may allow a satellite telecommunications system to plan, execute, and monitor routine recirculation of the fluid while in the STS 200. In certain embodiments, the fluid may be recirculated up to at least one tank volume at least once every twenty-four hours. In certain embodiments, the information handling system may be a mobile computer, PLC, handheld device, or other suitable instrument which can permit an operator to monitor and control the STS 200. In certain implementations, the STS 200 may include a control panel (not shown) thereon to facilitate local monitoring and control of the STS 200 by an operator.

In certain implementations, the execution of the cement job may be scheduled in advance. The operator may execute the cement job in any suitable manner known to one of ordinary skill in the art. For example, in certain implementations, the operator may use a mobile information handling system with remote access to the STS 200 as discussed above. In certain embodiments, the remote access may be facilitated by a wired or wireless communication system. The structure and operation of such communication systems is well known to those of ordinary skill in the art and will, therefore, not be discussed in detail herein. This mobile information handling system may be used to communicate with the control system 250 through a communication device 260 in order to control the operation of the STS 200. For instance, the mobile information handling system may be used to supply the prejob planning data and may contain the software to execute the cement job. For example, the control system can be a Siemens S7-317 Programmable Logic Controller. In other embodiments, the operators may use any information handling system with remote access to the control system 250 and prejob planning data and software to execute the cement job. Alternatively, the operators may execute the cement job manually using a control panel provided on the STS 200 as discussed above.

Prior to pumping the cement slurry downhole, the STS 200 may be connected to a rig pump (not shown) through one or more pumping outlets 270. The pipes or hoses may connect the discharge of a centrifugal pump on the STS 200 to the suction of the rig pump. Alternatively, the STS 200 may displace the ELS into the well bore without a rig pump. In certain embodiments, an accelerator compound or other liquid additives may be stored in an accelerator tank 230 and may be mixed during the cement job. For example, the STS 200 may have a plurality of tanks, where one tank is an accelerator tank 230 and the other tanks are ELS storage tanks 220. At the time of the cement job, the ELS may be pumped from one of the ELS storage tanks 220 into a centrifigal pump 330 where the accelerator compound is then mixed with ELS at the point of the centrifugal pump 330 and the resulting accelerator-ELS mixture then flows into the rig pump. The accelerant may be stored in the accelerator tank 230 as a liquid or dry additive.

In certain embodiments, the STS 200 may include one or more dry additive tanks In certain embodiments, the dry additive tanks may be mounted on top of one of the tanks 220 (not shown). The dry additive tank may be a small tank of various shapes with a dry powder feeder supplying a controlled amount of dry powder to eductor type mixer. The dry additive tank may have the ability to increase pressure, allowing a dry additive to be pneumatically conveyed to a dry additive mixer. In certain embodiments, the dry additive mixer may supply the dry powder to an eductor type mixer (not shown). The dry additive tank may be equipped to regulate and monitor flow of dry materials to the dry additive mixer. For instance, the dry additive tank may include one or more pressure transducers, one or more weight scales, and one or more valves. This equipment may allow manual or remote control of dry material flow from the dry additive tank. Specifically, in the same manner discussed above with respect to the STS 200, the dry additive tank may be communicatively coupled to an information handling system through a wired or wireless communication device 260. Accordingly, the dry additive tank may transmit signals indicative of its state of operation and/or receive control signals from a remote information handling system.

In certain implementations, the flow of a dry additive into a mixer with the slurry may be controlled to regulate the ratio of ELS and any accelerator compound or dry additive added thereto. The STS 200 may allow samples to be taken to ensure the ELS meets the desired rheology and density parameters as required for a job, as well as mechanical properties of set product after adding the accelerant(s).

The present disclosure minimizes the portion of the cementing operation performed at the rig location. The dry bulk and water, less accelerant, may be mixed in an ELS storage tank 220 of the STS 200 to form a slurry. In one embodiment, the mixing may be performed in a STS 200 located in a central location, where time and quality can be controlled much more closely. The liquid slurry may then be transported to the rig site and loaded into another STS 200 so that slurry can be recirculated and rolled in order to maintain quality of the cement slurry. Additional water and/or dry or liquid additives may be added at rig location if required to ensure slurry is properly designed for well conditions. At a desired time, the slurry may be mixed with proper amount of an accelerant and sent to rig pumps to be pumped down the hole for cement placement. In another embodiment, the dry ingredients may be transported to the rig site, where the dry ingredients may be mixed in an ELS storage tank 220 of the STS 200 to form a slurry.

As will be appreciated by one of ordinary skill in the art, the STS 200 may increase the efficiency of a surface, intermediate, production, plug and abandon, or any cement job on an oil or gas well by reducing the cost, time, and labor required. The number of operators required for a given job and the amount of time needed for the job may be reduced using the method and system disclosed herein. The STS 200 reduces the complexity of the required equipment as well. In addition, production of ELS in a liquid form at a centralized facility increases ELS reliability by mixing small amounts of additives with large quantities of base material more accurately in a liquid state. The ability to prehaul ELS to the rig site in advance of execution of the cement job reduces lag time between ordering a cement job and performing the cement job because transportation and setup can occur in anticipation of a cement job.

Finally, the wide density application range of the ELS allows the same base ELS to be used to pump both lead and tail sections of surface and intermediate jobs by changing water, accelerant, and specific additive concentrations.

Using the disclosed cementing method, the ELS may be prepared well in advance of a future cement job and may remain in a dry or liquid state for weeks if needed. This method allows the ELS and accelerant mixture to be prepared at any time leading up to a cement job, instead of requiring the driller to call the cement crew and equipment to location when they are needed and attempting to anticipate the exact time the wellbore will be ready for the cement job, which can result in several hours, or days, of wasted time that could be spend cementing another well. When the job is ready to be pumped, an accelerator (such as calcium chloride) can be added to the stored ELS, which will start the “setting time clock” resulting in the ELS becoming a solid after a designed period of time. This designed period of time is sufficient to allow the cement to be pumped into place in the well bore.

Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. The indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

Claims

1. A method of providing zonal isolation of subterranean formations, comprising:

mixing a dry blended material with a liquid at a central location to create a suspension;

transferring the suspension to one or more storage tanks at the central location;

recirculating the suspension in the one or more storage tanks at the central location;

transferring the suspension to one or more storage tanks at a rig site;

recirculating the suspension in the one or more storage tanks at the rig site; and

pumping the suspension into a well.

2. The method of claim 1, further comprising adding an accelerator to the suspension at the time of pumping.

3. The method of claim 2, further comprising adding at least one additive to the suspension at a designated time prior to pumping.

4. The method of claim 2, further comprising foaming the suspension after adding the accelerator.

5. The method of claim 1, further comprising testing the suspension at the central location.

6. The method of claim 5, further comprising adjusting the properties of the suspension in response to the testing at the central location.

7. The method of claim 1, further comprising testing the suspension at the rig site.

8. The method of claim 7, further comprising adjusting the properties of the suspension in response to the testing at the rig site.

9. The method of claim 1, wherein the one or more storage tanks comprise at least one of a suspension storage tank, an accelerant storage tank, and an additive storage tank.

10. The method of claim 1, further comprising storing the suspension in the one or more storage tanks at the central location.

11. The method of claim 1, further comprising storing the suspension in the one or more storage tanks at the rig site.

12. A method of providing zonal isolation of subterranean formations, comprising:

mixing a dry blended material with a liquid in one or more storage tanks at a rig site to create a suspension;

recirculating the suspension in the one or more storage tanks at the rig site; and

pumping the suspension into a well.

13. The method of claim 12, further comprising adding an accelerator to the suspension at a designated time prior to pumping.

14. The method of claim 12, further comprising adding at least one additive to the suspension at a designated time prior to pumping.

15. The method of claim 13, further comprising foaming the suspension after adding the accelerator.

16. The method of claim 12, further comprising testing the suspension at the rig site.

17. The method of claim 16, further comprising adjusting the properties of the suspension in response to the testing at the rig site.

18. The method of claim 12, wherein the one or more storage tanks comprise at least one of a suspension storage tank, an accelerant storage tank, and an additive storage tank.

19. The method of claim 12, wherein the dry blended material is mixed in the one or more storage tanks at a rig site to create a suspension.

20. A method of providing zonal isolation of subterranean formations, comprising:

mixing a dry blended material with a liquid in one or more storage tanks at a rig site to create a suspension;

recirculating the suspension in the one or more storage tanks at the rig site;

storing the suspension in the one or more storage tanks at the rig site

adding at least one additive to the suspension at a designated time prior to pumping; and

pumping the suspension into a well.