Abstract: There is provided a method of testing a subterranean formation for fracture condition, including the steps of creating a side bore into the wall of a well traversing the formation, sealing the wall around the side bore to provide a pressure seal between the side bore and the well, pressurizing the side bore beyond a pressure inducing formation fracture while maintaining the seal and monitoring the pressure to identify the fracture condition.

Abstract: A method of testing the performance of a stimulation fluid by placing a sample of the stimulation fluid or a precursor thereof into the body of a downhole tool, positioning the tool in juxtaposition with a rock face at a downhole location, forming a sealing contact between the rock face and the tool; and injecting the sample into the rock face while monitoring pressure and/or flow rates during the injection of the sample into and/or production of formation fluid from the rock face to derive a measure of the effectiveness of the stimulation fluid in creating openings in the rock face.

Abstract: A method for determining the location and height of a fracture in a subterranean formation using a neutron emitting logging tool. The method includes obtaining a pre-fracture data set, fracturing the formation with a slurry that includes a proppant doped with a high thermal neutron capture cross-section material, obtaining a post-fracture data set, comparing the pre-fracture data set and the post-fracture data set to determine the location of the proppant, and correlating the location of the proppant to a depth measurement of the borehole to determine the location and height of the fracture. Using a pulsed neutron capture tool, it is also possible to determine whether the proppant is located in the fracture, in the borehole adjacent to the fracture, or in both. The method may also include a plurality of post-fracture logging procedures used to determine various fracture and production characteristics in the formation.

Abstract: A method for determining flow distribution in a formation having a wellbore formed therein includes the steps of positioning a sensor within the wellbore, wherein the sensor generates a feedback signal representing at least one of a temperature and a pressure measured by the sensor, injecting a fluid into the wellbore and into at least a portion of the formation adjacent the sensor, shutting-in the wellbore for a pre-determined shut-in period, generating a simulated model representing at least one of simulated temperature characteristics and simulated pressure characteristics of the formation during the shut-in period, generating a data model representing at least one of actual temperature characteristics and actual pressure characteristics of the formation during the shut-in period, wherein the data model is derived from the feedback signal, comparing the data model to the simulated model, and adjusting parameters of the simulated model to substantially match the data model.

Abstract: Radar ranging data are collected from a down hole tool at various depths in a fractured well bore, and analyzed to provide a profile of the length of each wing of the fracture as a function of depth. The height of the fracture is determined from the vertical positions where the fracture is just observed or no longer observed as the tool is raised or lowered. For consecutive depths along the fracture (and for selected elevations from each depth for the case of a switchable antenna beam), reflection intensity as a function of range is measured. Simulated radar data are computed from a fracture model having the height of the fracture begin measured. The fracture model is varied and the resulting simulated data are correlated with the survey data until a match of minimal error is determined.

Abstract: Methods including the steps of selecting a target fracture geometry for a portion of a subterranean formation; selecting a target tip pressure and a target back flow pressure based at least in part on a calculation for the target fracture geometry; selecting a target surface pressure and a target bottom-hole pressure based at least in part on a calculation for the target tip pressure and the target back flow pressure; and introducing a slurry fluid comprising proppant particulates into one or more fractures in the portion of the subterranean formation. The surface pressure corresponds to the target surface pressure, and bottom-hole pressure corresponds to the target bottom-hole pressure.

Abstract: A method of method of determining relative contributions of two or more producing subterranean sources to a total flow is described using the steps of selecting a subset from a set of identifiable components in the total flow and using the subset to determine the relative contributions of two or more producing subterranean sources, wherein the subset is selected based on the sensitivity of the determination step to errors in the measurement of concentrations of said identifiable components.

Abstract: Systems and methods for the automated positioning of pads and orienting of slot templates for the pads. The systems and methods also include automated adjustment of well path plans from a pad to selected well targets.

Abstract: A process for fracturing a selected region of a formation including: introducing a supply of fracturing fluid to the region of the formation until a first threshold is reached, adjusting the flow of the fracturing fluid to the region of the formation to reach a second threshold, adjusting the flow of the fracturing fluid to the region of the formation to reach a third threshold and ceasing flow of the fracturing fluid to region of the formation, the fracturing fluid being a non-participating gas and including a proppant in at least one of the stages of flow of the fracturing fluid.

Abstract: The present invention refers to a method for detecting the geometry of underground fractures comprising the steps consisting of introducing a filling material (14) into an underground fracture (11) to form a pack of filling material (14); transmitting an electromagnetic field into the fracture (11); detecting at least one reflected signal of the electromagnetic field transmitted; and processing the at least one detected signal to reconstruct the geometric and dimensional characteristics of the pack of filling material (14); and it is characterised in that the electromagnetic field transmitted into the fracture (11) has a frequency comprised in the range of between 30 megahertz and 250 megahertz and in that said filling material is not added with any additives. The present invention also refers to a system for detecting the geometry of underground fractures for implementing the aforementioned method.

Abstract: Articles and methods utilizing radiation susceptible materials are provided herein. In one aspect, a proppant, a treatment fluid, or both, may comprise a radiation susceptible material. In another aspect, a method is provided comprising disposing in a formation fracture, a proppant and/or a treatment fluid that comprises a radiation susceptible material, irradiating the radiation susceptible material with neutrons, measuring gamma-radiation emitted from the radiation susceptible material in a single pass, and determining formation fracture height from the measured gamma-radiation. The single-pass may be a continuous process or a periodic process.

Abstract: A method for managing a fracturing operation. In one implementation, the method may include positioning one or more sources and one or more receivers near a hydrocarbon reservoir; pumping a fracturing fluid into a well bore of the hydrocarbon reservoir; performing a survey with the sources and the receivers during the fracturing operation; comparing the baseline survey to the survey performed during the fracturing operation; analyzing one or more differences between the baseline survey and the survey performed during the fracturing operation; and modifying the fracturing operation based on the differences.

Abstract: Prior to a hydraulic fracturing treatment, the requisite injection rate for a desired propped fracture length of a fracture may be estimated with knowledge of certain physical properties of the proppant and transport fluid such as fluid viscosity, proppant size and specific gravity of the transport slurry as well as fracture geometry and the fracture length.

Abstract: A well bore in a subterranean formation includes a signaling subsystem communicably coupled to injection tools installed in the well bore. Each injection tool controls a flow of fluid into an interval of the formation based on a state of the injection tool. Stresses in the subterranean formation are altered by creating fractures in the formation. Control signals are sent from the well bore surface through the signaling subsystem to the injection tools to modify the states of one or more of the injection tools. Fluid is injected into the stress-altered subterranean formation through the injection tools to create a fracture network in the subterranean formation. In some implementations, the state of each injection tool can be selectively and repeatedly manipulated based on signals transmitted from the well bore surface. In some implementations, stresses are modified and/or the fracture network is created along a substantial portion and/or the entire length of a horizontal well bore.

Abstract: In one aspect, the invention relates to a method for “tagging” proppants so that they can be tracked and monitored in a downhole environment, based on the use of composite proppant compositions containing dispersed fillers whose electromagnetic properties change at a detectable level under a mechanical stress such as the closure stress of a fracture. In another aspect, the invention relates to composite proppant compositions containing dispersed fillers whose electromagnetic properties change under a mechanical stress such as the closure stress of a fracture. The currently preferred embodiments use substantially spherical thermoset nanocomposite particles where the matrix comprises a terpolymer of styrene, ethylvinylbenzene and divinylbenzene, a PZT alloy manifesting a strong piezoelectric effect or Terfenol-D manifesting giant magnetostrictive behavior is incorporated to provide the ability to track in a downhole environment, and carbon black particles possessing a length that is less than 0.

Abstract: A method for “tagging” proppants so that they can be tracked and monitored in a downhole environment, based on the use of composite proppant compositions comprising a particulate substrate coated by a material whose electromagnetic properties change at a detectable level under a mechanical stress such as the closure stress of a fracture. In another aspect, the invention relates to composite proppant compositions comprising coatings whose electromagnetic properties change under a mechanical stress such as the closure stress of a fracture. The substantially spherical composite proppants may comprise a thermoset nanocomposite particulate substrate where the matrix material comprises a terpolymer of styrene, ethylvinylbenzene and divinylbenzene, and carbon black particles possessing a length that is less than 0.

Abstract: Optimizing reservoir production in a commingled hydraulically fractured reservoir by allocating commingled system production data to each of the individual completed intervals in the system, calculating the reservoir and fracture properties for each completed reservoir layer, and recalibrating the commingled and individual layer production data by accounting for the individual completed interval reservoir and fracture properties.

Abstract: A method for managing a fracturing operation. In one implementation, the method may include positioning a seismic source and at least one seismic receiver near a hydrocarbon reservoir; pumping a fracturing fluid into a well bore of the hydrocarbon reservoir; performing a seismic survey with the seismic source and the at least one seismic receiver during the fracturing operation; and identifying locations of the fracturing fluid within subsurface formations in which the hydrocarbon reservoir is located.

Abstract: A method for fracturing a wellbore while drilling a wellbore includes inserting a drill string into a wellbore. A fluid is pumped into at least one of an interior passage in the drill string and an annular space between a wall of the wellbore and the drill string. At least one of a pressure and a temperature of the fluid proximate a lower end of the drill string is measured and the measurements are transmitted to the surface substantially contemporaneously with the measuring. At least one of a flow rate and a pressure of the fluid is controlled in response to the measurements to selectively create fractures in formations adjacent to the wellbore.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to generating probabilistic information on characteristics of natural fractures of a subterranean formation. Fitted fracture models are generated based on microseismic event data for a subterranean region. The fitted fracture models represent estimated locations of fractures in the subterranean region. A distribution of fracture parameter values is generated based on the fitted fracture models. The distribution includes fracture parameter values and a probability associated with each fracture parameter value. Generating the fitted fracture models may include, for example, fitting a plane, a line or another type of equation to the measured locations of microseismic events. In some implementations, an injection treatment may be simulated and/or designed based on the probability distribution.

Abstract: A method and apparatus for orchestrating multiple fractures at multiple well locations in a region by flowing well treatment fluid from a centralized well treatment fluid center includes the steps of configuring a well treatment fluid center for fracturing multiple wells, inducing a fracture at a first well location, measuring effects of stress fields from the first fracture, determining a time delay based in part upon the measured stress effects, inducing a second fracture after the time delay at a second location based upon the measured effects, and measuring the stress effects of stress fields from the second fracture. Sensors disposed about the region are adapted to output effects of the stress fields. Location and orientation of subsequent fractures is based on the combined stress effects of the stress fields as a result of the prior fractures which provides for optimal region development.

Abstract: A method of injecting a treatment fluid into a portion of a subterranean formation, comprising providing a treatment fluid having a viscosity; determining the breakdown pressure of the portion of the subterranean formation; calculating the maximum sustainable flow rate for the treatment fluid; and, injecting the treatment fluid into the portion of the subterranean formation at a flow rate less than or equal to the maximum sustainable flow rate for the treatment fluid. A method of injecting a treatment fluid into a portion of a subterranean formation, comprising providing a treatment fluid having a viscosity; determining the breakdown pressure of the portion of the subterranean formation; calculating the maximum allowable treatment fluid viscosity; adjusting the viscosity of the treatment fluid to a viscosity less than or equal to the maximum allowable treatment fluid viscosity; and injecting the treatment fluid into the subterranean formation at the selected treatment fluid flow rate.

Abstract: A method includes identifying application parameter(s) including a subterranean formation temperature, determining a breaker particle size in response to the application parameter(s), providing a treatment fluid including a carrier fluid and a granular breaker sized according to the breaker particle size, and treating the subterranean formation with the treatment fluid. The granular breaker is a metallic peroxide which may be an alkaline peroxide and/or zinc peroxide. The application parameter(s) may further include a flowback wait time, a composition of the metallic peroxide, a gel loading of the carrier fluid, and a permeability of the subterranean formation. The breaker particle size may include a breaker large particle size that is not greater than 25% larger than a breaker small particle size. At least 90% of the breaker particles may be sized between the breaker small particle size and the breaker large particle size.

Abstract: A method for determining distribution data for a disposal domain parameter to increase assurance in a cuttings injection process, including performing a fracturing simulation using a site specific datum to obtain a fracturing result, determining a probability of creating a new fracture using the fracturing result and a probability model, performing a plurality of fracturing simulations using the probability and a distribution associated with the probability to obtain disposal domain information, and extracting the distribution data for the disposal domain parameter from the disposal domain information.

Abstract: A method for breaking a fracturing fluid includes identifying application parameter(s) including a subterranean formation temperature, and determining an acid precursor concentration in response to the application parameter(s). The method further includes providing a treatment fluid including a carrier fluid, a metallic peroxide breaker, and an amount of an acid precursor according to the acid precursor concentration, and treating the subterranean formation with the treatment fluid. The application parameter(s) may further include a flowback wait time, a composition of the metallic peroxide breaker, a gel loading of the carrier fluid, and/or a permeability of the subterranean formation. The metallic peroxide breaker may include an alkaline peroxide and/or a zinc peroxide. The acid precursor may include polylactic acid and/or polyglycolic acid.

Abstract: A downhole system comprises (a) a wellbore deployable container comprising an operational control circuit and a power source operationally in communication with the operational control circuit, each disposed within the container; a wellbore deployable, controllable downhole electronic frac fluid flow control module further comprising a wellbore deployable container receiving seat; and a data handling circuit; (b) a wellbore deployable, data transmission capable gauge deployable near the control module; and (c) a surface system operatively in communication with the operational control circuit and/or the control module.

Abstract: A method of designing a response to a fracture behavior of a formation during re-injection of cuttings into a formation, the method including obtaining a pressure signature for a time period, interpreting the pressure signature for the time period to determine a fracture behavior of the formation, determining a solution based on the fracture behavior of the formation, and implementing the solution is disclosed. A method of assessing a subsurface risk of a cuttings re-injection operation, the method including obtaining a pressure signature for a time period, interpreting the pressure signature to determine a fracture behavior of the formation, characterizing a risk associated with the determined fracture behavior of the formation, and implementing a solution based on the characterized risk is also disclosed.

Abstract: An injection backflow technique for measuring fracture surface area adjacent to a wellbore is disclosed. According to one embodiment, a method comprises measuring an initial temperature profile along the length of a wellbore. A tracer composition is injected into the wellbore at an initial concentration. The tracer composition includes a reactive tracer and a secondary tracer that is less reactive than the reactive tracer. The tracer composition diffuses within subterranean reservoir for a time. A secondary tracer concentration and a reactive tracer concentration are measured as a function of time. A reservoir fracture surface area is calculated using a reservoir fluid flow model.

Abstract: Stress rotation due to depletion can be estimated in reservoirs having an impermeable reservoir boundary. More specifically, the isotropic change in stress due to depletion, and the uniaxial stress resulting from a change in pore pressure across an impermeable boundary are both modeled as perturbations to an initial stress state. These perturbations can result in a rotation of the principal stress directions. Estimates of the stress rotation are helpful for hydraulic fracturing operations, because fracture tends to occur in a plane perpendicular to the least principal stress.

Abstract: A method and system model of the formation and rock matrices in a well site. A microseismic event from a hydraulic fracture in a well bore is recorded at a monitoring well site. The S-coda wave window of the microseismic event is identified. Q-factors for a set of frequencies within the S-coda wave window are then identified.

Abstract: Tubewaves are used for detection and monitoring of feature state to enhance stimulation operations and remediate failure conditions. For example, proper sealing of perforations may be confirmed based on lack of a reflection of a tubewave by the perforations. Alternatively, at least one of amplitude, frequency, attenuation, dispersion and travel time associated with a tubewave and reflection may be used to determine feature state. If a sealant fails during treatment then the failure condition is indicated by appearance of a tubewave reflection. Consequently, the stimulation operation can be stopped in a timely manner, and remediation by means, for example, of pumping diversion fluid or dropping of balls, can be reinitiated until the difference between the expected responses and responses measured by the instrument along the segment to be stimulated confirm that sealing has taken place and that stimulation of the intended zone can resume.

Abstract: A method of treating a subterranean formation penetrated by a wellbore includes preparing a treatment fluid with shear thinning, non-monotonic rheological properties, injecting the treatment fluid into the subterranean formation, and inducing shear rate softening phase transition in the treatment fluid. The non-monotonic rheology properties can be such that in the relationship between shear stress (?) versus strain rate ({dot over (?)}), where {dot over (?)}1<{dot over (?)}2<{dot over (?)}3<{dot over (?)}4, the shear stress values are ?1<?2?3??4, and ?3<?2 The method can heterogeneously deposit proppant or solid acid in a fracture. A system to fracture a subterranean formation includes the fracturing fluid, a wellbore to inject the fracturing fluid to propagate a fracture in the formation, and a rate controller to inject the fracturing fluid into the subterranean formation at a minimum volumetric rate to provide a shear stress at an inlet to the fracture that exceeds ?2.

Abstract: The invention is a method for inverting reservoir bi-axial anisotropy and identifying complicated fracture/cross-bedding system (104) by using tri-axial induction logs and wellbore survey/image log data. An inversion method is disclosed that uses all nine components that can be measured by tri-axial induction tools (101), plus borehole azimuth and deviation data, to solve for the tri-axial induction response in an arbitrary anisotropic formation due to the non-orthogonal bedding plane and fracture plane (or cross bedding plane). A mathematical formula is provided relating the conductivity tensor in the tool's reference frame to the conductivity tensor in a reference plane associated with the fracture/cross bedding planes (102). This equation is inverted (103) to yield the conductivity tensor components in the fracture/cross bedding coordinate system, along with dip and azimuth angles for both the fracture/cross bedding planes and the tool.

Abstract: Methods for determining whether to perform a stimulation treatment on a subterranean zone are disclosed. Process zone stress (“PZS”), indicative of a production potential of the subterranean zone, is determined, and a determination is made as to whether the PZS exceeds a preselected value. A PZS exceeding the preselected value may indicate a poor production potential, and a stimulation treatment of the subterranean zone may be avoided. As a result, a substantial cost saving associated with the avoided stimulation treatment may be realized.

Abstract: Subterranean formation treatment methods incorporating a rheology model which enables prediction of fluid rheology properties during a treatment operation, where the foundation of the model is a description of the reaction chemistry which describes how the number of crosslinks and broken polymer linkages develops in time under the influence of crosslinkers, breakers, and/or thermally induced effects and pressure effects. In one aspect, when used as a tool for simulating the fluid viscosity, the model can help optimizing the fluid design and optional breaker schedule for a hydraulic fracturing treatment.

Abstract: Example methods and apparatus to perform stress testing of geological formations are disclosed. A disclosed example downhole stress test tool for pressure testing a geological formation comprises first and second packers selectively inflatable to form an annular region around the tool, a container configured to store a fracturing fluid, wherein the fracturing fluid is different than a formation fluid and a drilling fluid, a pump configured to pump the fracturing fluid into the first and second packers to inflate the first and second packers and to pump the fracturing fluid into the annular region to induce a fracture of the geological formation, and a sensor configured to detect a pressure of the fracturing fluid pumped into the annular region corresponding to the fracture of the geological formation.

Abstract: A refracture-candidate diagnostic test is an injection of compressible or slightly compressible fluid at pressures in excess of minimum in-situ stress and formation fracture pressure with pressure decline following injection test recorded to detect a fracture retaining residual width from previous stimulation treatments. The diagnostic consists of small volume injections with injection time being a small fraction of time required for compressible or slightly compressible reservoir fluid to exhibit pseudoradial flow. The fracture-injection portion of a test can be considered as occurring instantaneously. Data measurements are transformed into a constant rate equivalent pressure transformation to obtain adjusted pressures or adjusted pseudovariables which are analyzed to identify dual unit-slope before and after closure periods confirming a residual retaining width.

Abstract: This patent delineates methods for quantifying and mitigating dip-induced azimuthal AVO effects in seismic fracture detection using Azimuthal AVO analysis by accurately accounting for the divergence correction and azimuthal dependence of the reflection angle. Solutions are provided for three cases: (1) dipping isotropic reservoirs; (2) anisotropic reservoirs with fractures aligned in arbitrary direction; and (3) anisotropic reservoirs where vertical fractures are aligned perpendicular to the dip direction.

Abstract: A method of injecting a treatment fluid into a portion of a subterranean formation, comprising providing a treatment fluid having a viscosity; determining the breakdown pressure of the portion of the subterranean formation; calculating the maximum sustainable flow rate for the treatment fluid; and, injecting the treatment fluid into the portion of the subterranean formation at a flow rate less than or equal to the maximum sustainable flow rate for the treatment fluid. A method of injecting a treatment fluid into a portion of a subterranean formation, comprising providing a treatment fluid having a viscosity; determining the breakdown pressure of the portion of the subterranean formation; calculating the maximum allowable treatment fluid viscosity; adjusting the viscosity of the treatment fluid to a viscosity less than or equal to the maximum allowable treatment fluid viscosity; and injecting the treatment fluid into the subterranean formation at the selected treatment fluid flow rate.

Abstract: Many reservoirs of interest include heavy oil. In such reservoirs, partly at normal temperatures, many instruments commonly used for formation evaluation may not be able to distinguish between heavy oil and bound water in the formation. Passive or active heating is used to elevate the temperature of the fluids in the formation. At elevated temperatures, distinguishing between heavy oil and bound water is easier. Of particular interest is the increase in the resolvability of the transverse relaxation time T2 of NMR spin echo measurements. Additionally, the dielectric constant and the loss tangents of water and heavy oil show different temperature and frequency dependence.

Abstract: A method includes hydraulically fracturing a subterranean formation with a first treatment fluid and allowing the hydraulic fracture to close. The method includes preparing a second treatment fluid having a damage removal agent including carbon dioxide. The second treatment fluid further includes a proppant pack damage removal agent including an oxidizer, a radical initiator, an acid, a solvent, and/or other damage removal agents. The method further includes injecting the second treatment fluid into the subterranean formation at a downhole pressure below a fracturing pressure for the subterranean formation. The method includes holding pressure on the formation while the second treatment fluid enhances formation and proppant pack permeability, and flowing the second treatment fluid back to the surface.

Abstract: A method for monitoring a fracturing operation in a target well comprising extending a seismic sensor in a tubing string to a first position in an well offset from the target well. A coolant fluid is circulated through the tubing string for a predetermined time. The tubing string is retracted to a second uphole position such that the cooled seismic sensor is exposed in the offset wellbore. A seismic signal emitted during the fracturing operation of the target well is sensed in the offset well.

Abstract: Methods, systems, and apparatus for inducing fractures in a subterranean formation and more particularly methods and apparatus to place a first fracture with a first orientation in a formation followed by a second fracture with a second angular orientation in the formation are provided. First and second fractures are initiated at about a fracturing location. The initiation of the first fracture is characterized by a first orientation line. The first fracture temporarily alters a stress field in the subterranean formation. The initiation of the second fracture is characterized by a second orientation line. The first orientation line and the second orientation line have an angular disposition to each other.

Abstract: Reservoir fractures are visualized using electrically active proppants to carry electric signals throughout the fracture. The electric signals are easily detected at the surface using RF antennae and a three-dimensional image of the fracture is generated.

Abstract: Methods and systems that utilize explosive and cryogenic means to establish fluid communication to areas away from the well bore walls are disclosed. A first fracture is induced in the subterranean formation. The first fracture is initiated at about a fracturing location and the initiation of the first fracture is characterized by a first orientation line. The first fracture temporarily alters a stress field in the subterranean formation. Explosives are then used to induce a second fracture in the subterranean formation. The second fracture is initiated at about the fracturing location and the initiation of the second fracture is characterized by a second orientation line. The first orientation line and the second orientation line have an angular disposition to each other.

Abstract: Disclosed herein is a method comprising disposing in a formation fracture, a proppant and/or a fracturing fluid that comprises a radiation susceptible material that comprises indium and/or vanadium; irradiating the radiation susceptible material with neutrons; measuring gamma-radiation emitted from the radiation susceptible material in a single pass; wherein the single pass does not involve measuring of background radiation from previous or subsequent logging passes; and determining formation fracture height from the measured gamma-radiation.

Abstract: An apparatus for testing a rheological property of a fluid with a particulate includes: (a) a receptacle having a cylindrical side wall enclosed by a bottom wall defining a cavity for receiving a fluid to be tested; (b) an axial support adapted to be positioned in the cavity of the receptacle, whereby relative rotational motion can be imparted to the receptacle and the axial support; (c) at least one inward projection extending inward from an inside surface of the receptacle; (d) at least one outward projection extending outward from the axial support; and (e) at least one projection for directing fluid flow that has at least one major surface angled or curved upward. A method of testing a rheological property of a fluid with a particulate includes: (a) placing a sample of the fluid and the particulate in the apparatus; (b) imparting relative rotational motion to the receptacle and the axial support; and (c) measuring the torque between the receptacle and the axial support.

Abstract: Method and apparatus for estimating a fluid driven fracture volume during hydraulic fracturing treatment of a ground formation. A series of tiltmeters are positioned at spaced apart tiltmeter stations at which tilt changes due to the hydraulic fracturing treatment are measurable by those tiltmeters. Tilt measurements obtained from the tiltmeters at progressive times during the fracture treatment are analysed to produce estimates of the fluid driven fracture volume at each of those times as the treatment is in progress. The analysis may be performed sufficiently rapidly to provide real time estimates of the fluid driven fracture volume and may also produce estimates of fracture orientation. The estimates of fracture volume may be compared with the volume of fluid injected to derive an indication of treatment efficiency.

Abstract: The present invention provides methods of producing high molecular weight polymer. A method of forming polycarbonate includes the step of combining in a reaction mixture a diaryl carbonate, a transesterification catalyst, an aliphatic dihydroxy compound, and a diacid compound in a reactor system. The temperature and pressure of the reactor system are adjusted to a first reactor setpoints and the reaction mixture is monitored to detect initiation of the exothermic oligomerization reaction. The reactor setpoint are adjusted to second reactor setpoints after detection of initiation of the exothermic oligomerization reaction. The reactor system is maintained at the second reactor setpoints to allow the reaction mixture to react to form an oligomer mixture.

Abstract: Prior to a hydraulic fracturing treatment, the estimated fracture length may be estimated with knowledge of certain physical properties of the proppant and transport fluid such as fluid viscosity, proppant size and specific gravity of the transport slurry as well as fracture geometry and the treatment injection rate. The estimated fracture length may be determined by a specific equation.