CONTINUOUS GRAVITY FEED SYSTEM FOR FEEDING ADDITIVES TO A DRILLING MUD SYSTEM

Abstract

An apparatus and a method is provided for feeding drilling fluid additives into drilling mud. The apparatus may have an additive containment device with a top and a bottom. The bottom of the additive containment device may be connected to an outlet. The other end of the outlet may be connected to a valve. A flow nozzle may be connected to the valve so that the flow rate of the additive from the flow nozzle into the drilling mud is substantially constant.

Description

BACKGROUND

Boreholes are frequently drilled into the Earth's formation to recover deposits of hydrocarbons and other desirable materials trapped beneath the Earth's surface. Traditionally, a well is drilled using a drill bit attached to the lower end of what is known in the art as a drillstring. The drillstring is traditionally a long string of sections of drill pipe that are connected together end-to-end through rotary threaded pipe connections. The drillstring is rotated by a drilling rig at the surface thereby rotating the attached drill bit. Drilling fluid, or mud, is typically pumped down through the bore of the drillstring and exits through ports at the drill bit. The drilling fluid acts to both lubricate and cool the drill bit as well as to carry cuttings back to the surface. Typically, drilling mud is pumped from the surface to the drill bit through the bore of the drillstring, and is allowed to return with the cuttings through the annulus formed between the drillstring and the drilled borehole wall. At the surface, the drilling fluid is filtered to remove the cuttings and is often recycled.

Various difficulties may be encountered during the drilling operation, such as a fluid loss event. Drilling also includes numerous operations, including drilling, running casing, finishing, and many others. Additionally, during the drilling operation, various earth formations may result in torque or drag issues at the drill bit. Drilling fluid additives may be added to the drilling mud to address these specific issues or operations, and may be added over a limited time period.

For example, when a drill bit is experiencing torque or drag issues, it may be desirable to add spotting beads, a micro-bead used to provide lubricity at the drill bit. Addition of spotting beads to the drilling mud may frequently be required for only two or three days at a time during the drilling operation. As a result, drilling rigs are typically not permanently equipped to add spotting beads to the drilling mud, and this addition is often performed by simply dumping bags of spotting beads into the mud system. This feed method may result in periodic and inconsistent lubricity at the drill bit and is labor intensive, both of which are undesirable.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a simplified schematic diagram of a gravity assisted drilling additive feed system according to embodiments herein.

FIG. 2 is a side view of a gravity assisted drilling additive feed system according to embodiments herein.

FIG. 3 is a top view of a gravity assisted drilling additive feed system according to embodiments herein, with a hinged top in an open position.

FIG. 4 is a side view of an outlet assembly useful with a gravity assisted drilling additive feed system according to embodiments herein.

FIG. 5A and FIG. 5B are side views of interchangeable nozzles useful with a gravity assisted drilling additive feed system according to embodiments herein, where a flow rate/time resulting from the nozzle is indicated on an exterior of the nozzle.

FIG. 6 is a simplified flow diagram of a process for feeding drilling additives to a mud system according to embodiments herein.

DETAILED DESCRIPTION

Embodiments disclosed herein relate to a continuous gravity feed system for feeding additives to a drilling mud system. More specifically, embodiments disclosed herein relate to a portable additive feed system that uses gravity to feed spotting beads to a mud system when needed during a drilling operation.

FIG. 1 illustrates one embodiment of an additive feed system 10. In the embodiment, the additive feed system 10 may include an additive containment device 12 having a top 14, a bottom 16 and side walls 30. The additive containment device 12 may hold additives to be added to a drilling mud. Additionally, the additive containment device 12 may be of any shape configured to hold the additives while allowing the additives to flow out the bottom 16. For example, the additive containment device 12 may be a cylinder or a rectangular prism. The top 14 may be removed from the additive containment device 12. The top 14 may also be hingedly connected to the side walls 30 of the additive containment device 12 for ease of opening and closing. The top 14 may be opened when adding additives and closed when additives are not being added. The bottom 16 may be shaped to convey the additives to an exit of the additive containment device 12. For example, the bottom 16 may be a frustoconical shape or a frusto-tetrahedral shape.

Three or more legs 32 may be attached to the bottom 16 of the additive containment device 12. The legs 32 may be fixed to the bottom 16 or may be removable. Referring to FIG. 1, the legs 32 may be substantially straight. Referring to FIG. 2 and FIG. 3, the legs 32 may flare outwardly to provide a more stable base.

Referring to FIG. 1, the additive containment device 12 may have a top flanged portion 26 and a bottom flanged portion 28. The top flanged portion 26 may include the top 14 of the additive containment device 12. Opposite the top 14, the top flanged portion 26 may have a flange 26F. The bottom flanged portion 28 may include the bottom 16 of the additive containment device 12. Opposite the bottom 16, the bottom flanged portion 28 may have a flange 28F. The top flanged portion 26 may be connected to the bottom flanged portion 28 at the flange 26F and the flange 28F to form the additive containment device 12. In this embodiment, the top flanged portion 26 may be connected to the bottom flanged portion 28 during operation of the additive feed system 10.

The additive feed system 10 may have an outlet 18 that has a proximal end and a distal end. The outlet 18 may be tapered so that the distal end is narrower than the proximal end. The proximal end of the outlet 18 may be connected to the bottom 16 of the additive containment device 12. The interior of the outlet 18 may be substantially smooth to limit or eliminate the additives from accumulating and impeding the flow of additive through the outlet 18. The distal end of the outlet 18 may be connected to a valve 20. The valve 20 may be any type of valve useful for solids flow. For example, the valve 20 may be configured so that it only has a fully on position and a fully off position with no intermediate positions. In some embodiments, the valve 20 may have no flow restrictions that may result in solids accumulation and potential for plugging of the valve or otherwise hindering solids flow when the valve is open. Such a full bore type valve may be beneficial for consistency of solids flow, especially with respect to a gravity feed system disclosed herein.

A screening member 24 may be disposed within additive containment device 12 intermediate the top 14 and the bottom 16. The screening member 24 may filter or screen the additives disposed within the containment device 12. The screening member 24 may limit or eliminate oversized solids or agglomerates from passing through the tank to the outlet 18, avoiding plugging of the feed system or damage or other issues with downstream equipment, such as a mud pump. In some embodiments, the screening member 24 may be fixed. In other embodiments, the screening member 24 may be removable. The screening member 24 may be disposed between the top flange portion 26 and the bottom flange portion 28. In further embodiments, the screening member 24 may be removed when the top flange portion 26 and the bottom flange portion 28 are disconnected. Alternatively, the screening member may be fixed to the top flange portion 26 coplanar with the flange 26F. Additionally, the screening member 24 may be fixed to the bottom flange portion 28 coplanar with the flange 28F

The valve 20 is also connected to a flow nozzle 22 having an outlet end 36 and a flow rate. The flow nozzle 22 reduces the additive flow area and may provide a substantially constant rate of additive flow from the outlet 18. The flow nozzle 22 may provide a substantially constant rate of flow of a drilling fluid additive from the outlet 18. The flow nozzle 22 may have a relatively smooth, tapered, inner surface transitioning from the outlet port side of the valve 20 to the inner diameter of the outlet end 36. As shown in FIG. 4, to respond to changing needs in the drilling mud system, the flow nozzle 22 may be interchangeable. During operation of the the additive feed system 10, the valve 20 may be closed, and the flow nozzle 22 with a first flow rate may be changed for the flow nozzle 22 with a second flow rate.

The additive containment device 12 may have an internal volume in the range from about 5 gallons to about 150 gallons or more, and the desired volume may depend upon the type and size of additive and the desired flow rate of additive through the outlet 18 and the nozzle 22. The internal volume of the additive containment device 12 may affect the frequency that the additive containment device 12 must be refilled. In some embodiments, the internal volume of the additive containment device 12 may be in the range from about 10 to about 50 gallons; in the range from about 20 to 40 gallons in other embodiments, such as about 30 gallons. The volume of additives within the additive containment device 12 may be visually observed via opening of the top 14, tapping of the sides of the additive containment device 12 to gauge the level, or via one or more sight glasses (not shown) disposed in the side walls 30.

The additive containment device 12 may be made of a plastic material, resulting in a light weight, portable system. Because water may result in agglomeration of some additives, use of a plastic body, such as polypropylene or a vinyl polymer, may result in less moisture condensation within the additive containment device 12. Additionally, plastic may also result in no static charge accumulation to provide for safe operation in hazardous environments.

The substantially constant rate of flow of the drilling fluid additive is provided via an inner diameter of the outlet end 36 of the nozzle 22. The restriction of flow area of the nozzle 22 through which the solids may pass results in a relatively constant rate of solids to flow via gravity from the additive containment device 12. For example, for spotting beads, such as ALPINE spotting beads, having an average diameter in the range from about 70 microns to 1000 microns, a nozzle having a 1/4 inch inner diameter may provide for a flow rate of about 43 lb/h; a nozzle having a 3/8 inch inner diameter may provide for a flow rate of about 130 lb/h, and a nozzle having a 1/2 inch inner diameter may provide for a flow rate of about 200 lb/h. As shown in FIG. 4, the flow nozzle 22 may be adjustable or interchangeable, such as via threading, quick connects, or other means known to those skilled in the art. Adjustable or interchangeable nozzles having these and other inner diameters may thus provide for a desired, consistent, flow rate of drilling fluid additive, where an operator may select the appropriate nozzle or flow area to achieve the desired additive composition in the drilling mud. Interchangeable nozzles, such as illustrated in FIG. 5A and FIG. 5B, may be marked or otherwise identified to indicate the flow rate of drilling fluid additive through the nozzle or the approximate time for a (50-lb) bag of additive to dispense, thus providing a means to achieve a desired concentration of additive in the mud system and an indication of the approximate amount of time required to empty additive containment device 12.

Referring now to FIG. 6, a simplified flow diagram of a process for feeding drilling fluid additives to a mud system according to embodiments herein is illustrated. The above described gravity feed systems may be used to continuously feed drilling fluid additives, such as spotting beads, to a drilling fluid or mud system. While such a system may be permanently located proximate a mud system, it is envisioned that systems herein may be used intermittently during drilling processes, such as during operations or times when spotting beads or other additives are required.

When needed for the temporary feeding of additives to a mud system, the additive feed system 10 may be delivered to a drilling site or drilling rig, assembled (if necessary) and located proximate a mud system. For example, an “open” mud tank 40 containing a drilling fluid or drilling mud 42 may have a flow conduit 44 feeding a mud pump 46. The drilling mud 42 flows from the mud tank 40 through the conduit 44 and enters the suction of the mud pump 46. The drilling mud 42 is then discharged to an outlet conduit 48 and fed downhole through the drill string to the drill bit to provide lubrication and drill cuttings removal. The additive feed system 10 may be located over a grating 50 or opening in the flow conduit 44 to allow gravity feed of the additive from the nozzle 22 into the mud system proximate the suction of the mud pump 46.

Following proper location of the additive feed system 10, a drilling fluid additive may be disposed within the additive containment device 12, such as via opening and closing of the top 14. The valve 20 may then be opened to initiate flow of the additive through the nozzle 22 into the the mud system via the grating 50. As needed, additional additive may be added to additive containment device 12 so as to provide continuous flow of additive over an extended period of time. The frequency of such additions may depend upon the size of the additive containment device 12 and the flow rate of the nozzle 22, as described above. Should the concentration of the additive need to be adjusted during use, the valve 20 may be closed and the nozzle 22 changed. A flow conduit, such as a pipe, tube, or hose (not illustrated), may be connected to the nozzle 22 to guide the flow of additive from the nozzle 22 to the mud system feed point, such as the grating 50, minimizing effects of weather, wind, and other external factors as may be present at a drilling location or drilling rig.

When the drilling fluid additive is no longer required for drilling operations, the additive containment device 12 may be cleaned, disassembled, and, if necessary, removed from the drill site or drilling rig.

While described above with respect to an “open” mud system, location and operation of the additive feed system 10 may be performed in other manners as appropriate to the respective mud system.

As an example of using the additive system during a drilling operation, the lubricity of the drill bit may be increased using spotting beads, such as when a drill bit is experiencing drag and/or torque issues. Spotting beads may be disposed in the additive containment device 12 and fed to the suction side of the pump 46. The flow rate of spotting beads into the drilling fluid may be selected to provide a concentration of spotting beads in the drilling mud in the range from about 2 to about 15 lb/bbl, such as in the range from about 8 to about 10 lb/bbl. The drilling beads may then travel through the conduit 48 to the drill bit, where the micron size spherical beads may lubricate the drill bit.

Embodiments herein may supply a consistent, uniform mixture of drilling fluid additives, such as spotting beads, in a drilling mud. The uniform mixture of beads resulting from the consistent feed rate provided by systems herein, for example, may provide for a consistent, controllable supply of spotting beads, resulting in a constant improvement in lubricity at the drill bit. In contrast, present methods, such as manual dumping of bags of beads, result in “pill” type flow of spotting beads or otherwise inconsistent concentrations of beads in the drilling fluid, resulting in inconsistent lubricity at the drill bit. As a result, embodiments herein may eliminate the human factor and significantly improve drilling performance, including rate of penetration. Additionally, as compared to manual dumping, feed systems according to embodiments disclosed herein may require less manpower and may prevent oversized materials from accidentally being introduced to the system.

Feed systems according to embodiments herein may be relatively small in size, especially compared to the mud tanks (that may be 2000 bbl or larger in volume), portable, lightweight, and easy to transport, install, and dismantle. Additionally, embodiments herein may provide for interchangeable nozzles to accurately and predictably control the flow rate of drilling fluid additives. The relatively simple operation of the gravity feed system may thus improve overall operations at a drilling site or drilling rig and may be extremely beneficial, especially for short duration needs, such as spotting.

Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.

Claims

1. An apparatus comprising:

an additive containment device having a top and a bottom;

an outlet having a proximate end and a distal end wherein the proximate end is connected to the bottom of the additive containment device;

a valve connected to the distal end of the outlet; and

a flow nozzle connected to the valve wherein the flow rate of the additive from the flow nozzle is substantially constant.

2. The apparatus of claim 1 further comprising a screening member disposed intermediate the top and the bottom.

3. The apparatus of claim 1 further comprising at least three legs attached to the bottom of the additive containment device.

4. The apparatus of claim 1 wherein the top of the additive containment device is removable.

5. The apparatus of claim 1 wherein the additive containment device comprises a flanged top portion and a flanged bottom portion.

6. The apparatus of claim 3 wherein the legs are removable.

7. The apparatus of claim 1 wherein the top of the additive containment device is hingedly connected to the additive containment device.

8. The apparatus of claim 5 wherein the screening member is disposed within the additive containment device intermediate the flanged top portion and the flanged bottom portion and further wherein the screening member is removable.

9. The apparatus of claim 5 wherein the flanged bottom portion of the additive containment device is frustoconical.

10. An apparatus comprising:

an additive containment device having a top, a bottom, a top flanged portion and a bottom flanged portion wherein the top portion is removable;

a screening member intermediate the top flanged portion and the bottom flanged portion of the additive containment device wherein the screening member is removable;

an outlet having a proximate end and a distal end wherein the proximate end is connected to the bottom of the additive containment device;

a valve connected to the distal end of the outlet; and

a flow nozzle connected to the valve wherein the flow nozzle is interchangeable.

11. The apparatus of claim 10 further comprising at least three legs connected to the bottom flanged portion of the additive containment device wherein the legs are removable.

12. The apparatus of claim 10 wherein the top of the additive containment device is hingedly connected to the additive containment device wherein the top has an open position and a closed position.

13. A method for continuous gravity feed of additives into drilling mud during a drilling operation, the method comprising:

selecting a drill fluid additive;

feeding the drill fluid additive into drilling mud, wherein the drill fluid additive is fed at a substantially constant flow rate and further wherein the drill fluid additive is fed by gravity;

mixing the drill fluid additive into the drilling mud;

pumping the mixture of the drill fluid additive and the drilling mud into the wellbore.

14. The method of claim 13 further comprising assembling an additive feed system after commencing the drilling operation.