Abstract: Method for estimating residual moveout in common image gathers (51) of seismic data for use in velocity tomography (57). The method iteratively (56) flattens (55) the common image gathers against a specified reference trace through the application of conjugate-gradient least-squares inversion (53). Different from other picking methods which need to identify and track strong amplitudes, the inventive method automatically inverts for the depth residual for every grid point in the image gather. There is no need to identify and track events.

Abstract: Method and apparatus for extending the horizontal distance through which wells can be drilled. A horizontal tubular is used to convey a drillstring from a drilling rig toward a target location and a mud return line and pump on the surface is used to pump drilling mud returning from the bit back to the drilling rig.

Abstract: An automated method for texture segmentation (11) of geophysical data volumes, where texture is defined by double-window statistics of data values, the statistics being generated by a smaller pattern window moving around within a larger sampling window (12). A measure of “distance” between two locations is selected based on similarity between the double-window statistics from sampling windows centered at the two locations (13). Clustering of locations is then based on distance proximity (14).

Abstract: Method, system and apparatus to produce hydrocarbons includes a packer apparatus with a swellable packer element around primary and secondary flow paths, the packer is configured to block flow in a portion of a wellbore annulus. The method includes disposing sand control devices having shunt tubes and a packer within a wellbore adjacent to a subsurface reservoir. The packer is then set within an interval, which may be an open-hole section of the wellbore, and gravel packing the sand control devices in different intervals. Hydrocarbons are produced by passing hydrocarbons through the sand control devices with different intervals providing zonal isolation. In some embodiments, intervals may be alternatively packed and plugged, wherein the plugged intervals are not packed.

Abstract: A flow restrictor device (10) for production tubing comprises: an obstructing member (18) arranged for movement between a first position where said obstructing member is located so as to form a seal with an edge of an aperture (14) formed in a wall of said production tubing and is arranged prevent fluid flow through said aperture, and a second position where said obstructing member is located so that the aperture is unobstructed; and a retaining arrangement (16) for restricting possible locations of said obstructing member to said first position, second position and positions therebetween.

Abstract: Downhole fluid injection systems are disclosure that can include a first well extending into a geological formation, and a fluid injector assembly located within the well. The fluid injector assembly can be configured to inject a liquid CO2/H2O-emulsion into the surrounding geological formation. CO2 sequestration methods are provided that can include exposing a geological formation to a liquid CO2/H2O-emulsion to sequester at least a portion of the CO2 from the emulsion within the formation. Hydrocarbon material recovery methods are provided that can include exposing a liquid CO2/H2O-emulsion to a geological formation having the hydrocarbon material therein. The methods can include recovering at least a portion of the hydrocarbon material from the formation.

Abstract: Selective placement of conformance treatments in multi-zone well completions. A method includes injecting a relative permeability modifier into a zone and optimizing a ratio of desired fluid to undesired fluid produced from the zone, including adjusting at least one flow control device between fully open and fully closed configurations. Another method includes injecting a relative permeability modifier into multiple zones, one at a time, via respective flow control devices, and then producing fluid from each of the zones. Another method includes identifying which of the zones to treat by, for each of the zones: a) closing flow control devices corresponding to the other zones, and b) evaluating fluid produced from the zone; and injecting a conformance treatment into the zones identified as the zones to treat.

Abstract: Zonal isolation apparatus includes at least one packer assembly and can be used in completing an open-hole potion of a wellbore, which open-hole portion extends through at least two subsurface intervals. The zonal isolation apparatus includes base pipe and filter medium, which together form a sand screen. Each packer assembly comprises at least two mechanically set packer elements. Intermediate the at least two mechanically set packer elements is at least one swellable packer element. The swellable packer element is actuated over time in the presence of a fluid such as water, oil, or a chemical. Swelling may occur should one of the mechanically set packer elements fail. The zonal isolation apparatus also includes alternate flow channel(s) that serve to divert gravel pack slurry from an upper interval to lower intervals during gravel packing operations. A method for completing a wellbore using the zonal isolation apparatus is also provided herein.

Abstract: A method to extract oil for a pool of oil in the ground utilizes an interconnected series of rotating helical blades extending from the surface of the ground through a canted bore to the pool of oil. The blades can be staggered and interconnected with a gear arrangement that moves oil from pool to pool and up to the surface of the ground.

Abstract: A pump system and method comprising a pump barrel adapted for use within a well. A reciprocating plunger disposed within the pump barrel and operatively engaging a connector between the plunger and a pumping unit. The connector operatively engages the pumping unit and further comprises an inner and outer portion with a groove between the inner and outer portions; one or more ports disposed between the inner and outer portions and accessing an inner cavity of the connector; and the inner portion further comprising one or more ports accessing the inner cavity of the connector. The pump system and method further comprising a cage valve to create hydraulic pressure to expel trapped debris.

Abstract: A method of operating an oil well comprises applying through a regenerative variable frequency drive AC electrical energy from a power grid to an AC electric motor to operate a drive mechanism of an oil well pump. The motor speed is regulated in a manner to optimize fluid production and maximize the operational life of the drive mechanism, decreasing motor speed by transferring the electrical energy to the power grid and increasing motor speed by transferring the electrical energy from the power grid to the motor. The drive mechanism has a predetermined stroke cycle and, over the course of each stroke cycle, the motor is operated at different regulated speeds initiated when the drive mechanism is at a predetermined position.

Abstract: A system for performing a downhole operation within a well during a production phase of the well includes a tubing string extending from a surface of the well to the downhole location. A lift system is positioned at the surface and is operably connected to the tubing string to axially lift and lower the tubing string, following positioning of the tubing string within the well, each time a substantial reduction in production gas flow and production liquid flow at a portion of the well is desired.

Abstract: A transportable modular process for exploiting a remote heavy oil resource or the like using steam assisted gravity drainage technology or the like. Said process comprising transportable preassembled and commissioned modules which when interconnected adjacent said remote heavy oil resource provide the ability to exploit said heavy oil resource or the like. Each module being preassembled and commissioned at the time of manufacture with the necessary piping and electrical wiring and other essential equipment for each module prior to being transported to adjacent the resource. Each module being, when transported to adjacent said resource, able to be readily interconnected with other process modules to enable an entire SAGD process or the like to be constructed adjacent said resource.

Abstract: A method for producing hydrocarbon fluids from an organic-rich rock formation to a surface facility is provided. The method may include heating the formation in situ to cause pyrolysis of formation hydrocarbons, and producing production fluids from the formation via two or more wells. The produced fluids have been at least partially generated as a result of pyrolysis of the formation hydrocarbons. In addition, the produced fluids comprise non-condensable fluids, or gases, which taken together have an averaged Wobbe Index which varies at a rate of more than 5% over a period of time. The method also includes controlling production from one or more of the wells such that a combination of the production fluids from the wells results in a combined gas stream that's averaged Wobbe Index varies at a rate of less than 5% over the period of time. The combined stream comprises combustible hydrocarbon fluids.

Abstract: A self-contained system for drilling a drainhole laterally to a wellbore that includes a drill head with a tool for boring a drainhole and a self-propelled device for advancing the head into the drainhole during boring; a relay unit lowered into the wellbore, arranged to position the drill head against the sidewall of the wellbore in order to initiate the boring of the drainhole laterally to the wellbore; a cable for supplying electric power to the drill head, reeled out from the relay unit; and a mechanical system for removing cuttings from the drainhole during boring, the debris removed falling downhole.

Abstract: An oil well pumping apparatus for pumping oil from a well to a wellhead provides a tool body that is sized and shaped to be lowered into the production tubing string of the oil well. A working fluid is provided that can be pumped into the production tubing. A prime mover is provided for pumping the working fluid. A flow channel into the well bore enables the working fluid to be circulated from the prime mover via the production tubing to the tool body at a location in the well and then back to the wellhead area. A pumping mechanism is provided on the tool body, the pumping mechanism including upper and lower spur gear or gears. The upper spur gear is driven by the working fluid. The lower spur gear is rotated by the first spur gear. The upper and lower spur gears are connected with a common shaft.

Abstract: A technique is provided to facilitate movement of fluids in wells where the fluids have a relatively high gas-to-liquid ratio. A submersible pump is combined with a separate, dedicated mixer. The dedicated mixer is positioned upstream of the components of the submersible pump designed to move the well fluid. The mixer reduces large gas structures and homogenizes the fluid flow fed into the submersible pump.

Abstract: A stator for a progressive cavity pump comprises a stator housing having a central axis, a first end, and a second end opposite the first end. In addition, the stator comprises a stator liner disposed within the stator housing. The stator liner has a first end and a second end opposite the first end. The first end of the stator liner is axially spaced from the first end of the stator housing. Further, the stator comprises a tag insert positioned in the stator housing between the first end of the stator housing and the first end of the stator liner. The tag insert has a through passage defining a radially inner surface that includes a tag shoulder.

Abstract: The present invention relates to a method and apparatus for reducing the occurrences of lateral wellbores being occluded by fines such as sand and silt. More specifically, the invention relates to discharging a portion of the output of an electrical submersible pump through nozzles that pass through the sidewalls of tubing, the tubing being located in the lateral wellbore.

Abstract: A method, system and apparatus associated with the production of hydrocarbons are described. One apparatus includes a swellable packer element around a primary and a secondary flow path, wherein the packer is configured to block flow in a portion of a wellbore annulus. One method includes disposing sand control devices having shunt tubes and a packer within a wellbore adjacent to a subsurface reservoir. The packer is then set within an interval, which may be an open-hole section of the wellbore. With the packer set, gravel packing of the sand control devices in different intervals may be performed. Then, hydrocarbons are produced from the wellbore by passing hydrocarbons through the sand control devices with the different intervals providing zonal isolation. In some embodiments, intervals may be alternatively packed and plugged, wherein the plugged intervals are not packed. In addition, the method may also include disposing the sand control devices and packer into the wellbore in conditioned drilling fluid.

Abstract: Fluids for use in hydrocarbon recovery operations include water and at least one organo-anionic surfactant. The fluids may be used in methods for conducting hydrocarbon recovery operations, such as drilling operations, completion operations, production operations, injection operations. The fluid may be adapted to remediate a NAF filter cake. Exemplary organo-anionic surfactants may include one or more of monoethanol ammonium alkyl aromatic sulfonic acid, monoethanol ammonium alkyl carboxylic acid, and mixtures thereof.

Abstract: In one aspect, an apparatus for controlling fluid flow between a formation and a tubular is provided, wherein the apparatus includes a retrievable communication device configured to be conveyed to a selected location in the tubular downhole. The apparatus also includes a control node configured to communicate with the retrievable communication device at the selected location, a flow control device coupled to and controlled by the control node and a sensor coupled to the control node, wherein the sensor and flow control device are downhole of the control node.

Abstract: Methods for hydrocarbon recovery from a subsurface formation include removing a mixture comprising hydrocarbons and particulate solids from a first formation. At least a portion of the hydrocarbons are separated from the particulate solids. The particulate solids are separated into a plurality of streams. A mixed slurry comprising a first portion of the plurality of streams is injected through a first pipe into the first formation. A waste stream comprising a second portion of the plurality of streams is injected through a second pipe into a second formation. The first formation and the second formation lie in a substantially vertical line.

Abstract: An electrical submersible pumping (ESP) system for use in a wellbore that can be assembled in the wellbore. Upper and lower pump tandems are fitted with connectors that align the tandems when coupled in the wellbore. The connectors on the lower tandems have bores with enlarged openings on upward facing surfaces. Downward pointing pins are on lower facing surfaces of the connectors on the upper tandems. The cross sectional area of each bore decreases with distance away from the openings, so that as the pins insert into the bores the pins move along a helical path that in turn rotates the upper tandem into a designated azimuth and into alignment with the lower tandem. Properly aligning the upper and lower tandems couples respective drive and driven shafts in the tandems as the upper tandem lands on the lower tandem.

Abstract: A method for altering flow conditions in a porous media containing hydrocarbons includes the steps of preparing a mixture of a surfactant, a co-surfactant and a carrier fluid; transporting the mixture to the porous media; and holding the mixture in the porous media in the presence of water for a period of time sufficient to form a water film on the surfaces of the porous media.

Abstract: Selective placement of conformance treatments in multi-zone well completions. A method includes injecting a relative permeability modifier into a zone and optimizing a ratio of desired fluid to undesired fluid produced from the zone, including adjusting at least one flow control device between fully open and fully closed configurations. Another method includes injecting a relative permeability modifier into multiple zones, one at a time, via respective flow control devices, and then producing fluid from each of the zones. Another method includes identifying which of the zones to treat by, for each of the zones: a) closing flow control devices corresponding to the other zones, and b) evaluating fluid produced from the zone; and injecting a conformance treatment into the zones identified as the zones to treat.

Abstract: Embodiments of the present invention relate to an apparatus and methods for enhanced well control in slim completions. An embodiment can include an electrical submersible pump (“ESP”) positioned within a casing and having at least a portion thereof extending outwardly from a production tubing positioned within the casing. The production tubing terminates adjacent a distal end portion of a pump discharge to thereby provide greater interstitial space between outer surfaces of the portion of the pump disposed to extend outwardly from the production tubing and inner walls of the casing. This increased interstitial space, for example, can assist in cost savings by reducing the rate of erosion damage to the ESP. Embodiments of the present invention can further include a valve connected to inner walls of the casing and positioned distal from the ESP to control the flow of hydrocarbons.

Abstract: The claimed invention relates to the downhole systems for extracting various fluids, in particular—for simultaneous extraction out of a number of producing formations. The inventive downhole system comprises a casing pipe and a tubing extending through said casing pipe, between which pipe and tubing formed are separate isolated cavities. Each one of which cavities communicates, via perforations, with a respective producing formation. In each one of the isolated cavities, to the tubing coupled is a hydraulic machine comprised by a motor and pump. The hydraulic machines in different isolated cavities being adapted to be adjusted independently. This system permits simultaneous extraction of fluids out of different producing formations, with independent controlling of such extraction in various formations. The claimed invention also relates to an immersion hydraulic machine used for extracting fluids.

Abstract: A system for production of oil and heavier gas fractions from a reservoir under a seabed includes a field installation with at least one production well and one injection well, a vessel with means to be connected to a loading and unloading station, and a receival plant configured to load and unload the vessel. The vessel includes a high-pressure three-phase separator, an injection compressor, and either water cleaning equipment or water injection equipment that the vessel can load high-pressure well fluid that is brought into the separator and separated to lighter gas fractions, oil and heavier gas fractions, and water, of which oil and heavier gas fractions are brought to high-pressure storage tanks in the vessel, which high-pressure storage tanks include high-pressure gas which thereby is displaced out of the tanks and injected into the reservoir together with the lighter gas fractions, via the injection compressor.

Abstract: This invention provides a positive displacement gas operated pump and pumping system for pumping fluids such as hydrocarbons/oil as well as solids that may be suspended in such fluids. More specifically, the invention relates to a method and apparatus for the recovery of hydrocarbons/oil from underground water tables and/or where water flooding has previously been used to further extract hydrocarbons/oil from underground areas, but economics prevent further recovery from such areas and/or wells.

Abstract: A method of producing a well fluid includes securing a motor to a string of outer tubing and lowering the outer tubing and motor into the well. A rotary pump is secured to a string of inner tubing and lowered into the outer tubing. The pump stabs into cooperative engagement with the motor. Supplying power to the motor rotates the pump, causing well fluid to flow into the outer tubing to an intake of the pump, which pumps the well fluid through the inner tubing to an upper end of the well. Removing the well fluid allows gas to flow up an annulus surrounding the outer tubing to the upper end of the well.

Abstract: One or more embodiments of a selectively openable and closable downhole tool. The wherein, the downhole tool can include an outer tubular member having an annulus port formed therethrough. The downhole tool can also include an inner tubular member. The inner tubular member can include an inner port. The inner port and annulus port can be selectively aligned to form a flow path therethrough by moving the inner tubular member relative to the outer tubular member. The downhole tool can also include a logic drum configured to selectively move the inner tubular member. The downhole tool can also include a piston assembly configured to move the logic drum.

Abstract: The method pertains to the oil and gas industry and can be used in the development of producing formations. A producing string (6) together with a sealing device (7) are lowered into a well (1) and the well (1) is divided into an upper cavity (8) and a lower cavity (9) with the aid of said sealing device (7) to establish a hydraulic connection between the well opening and the upper cavity and between the lower cavity and the producing formation, respectively. The installation of equipment (10) and a check valve is carried out stepwise. A washer fluid (4) is replaced by a washer fluid (15). The equipment (10) is passed through the sealing device (7) and the hydraulic connection between the well opening, the lower cavity and the producing formation is re-established along the annular channel.

Abstract: A method of cleaning a wellbore prior to the production of oil or gas is disclosed, wherein the wellbore has been drilled with an invert emulsion drilling mud that forms an invert emulsion filter cake. The method may include the steps of circulating a breaker fluid into the wellbore, where the breaker fluid includes an aqueous fluid, a water soluble polar organic solvent, a hydrolysable ester of a carboxylic acid, and a weighting age, and where the hydrolysable ester is selected so that upon hydrolysis an organic acid is released and the invert emulsion of the filter cake breaks.

Abstract: The present invention relates to an improved method for recovering hydrocarbons trapped in hydrate formations.

Abstract: A system for operating downhole equipment in a well includes a drive shaft extending from a surface of the well to a downhole location. A motor is positioned at the surface and is operably connected to the drive shaft to selectively rotate the drive shaft. A lift system is positioned at the surface and is operably connected to the drive shaft to axially lift and lower the drive shaft.

Abstract: An apparatus and process for gas, oil, and other fluid production using bailer technology with stimulation to enhance production. An enclosed apparatus and process for removing gas, oil, and/or other fluids from a well while reducing environmental impact. A novel divalve for simultaneously closing a conainer and dumping liquids into it.

Abstract: A free-standing riser system connects a subsea source to a surface structure. The system includes a concentric free-standing riser comprising inner and outer risers defining an annulus there between. A lower end of the riser is fluidly coupled to the subsea source through a lower riser assembly (LRA) and one or more subsea flexible conduits. An upper end of the riser is connected to a buoyancy assembly and the surface structure through an upper riser assembly (URA) and one or more upper flexible conduits, the riser also mechanically connected to a buoyancy assembly that applies upward tension to the riser. The riser may be insulated for flow assurance, either by a flow assurance fluid in the annulus, insulation of the outside of the outer riser, or both. The system may include a hydrate inhibition system and/or a subsea dispersant system. The surface structure may be dynamically positioned.

Abstract: Drilling fluids comprising polymers containing hydroxylated structural units are useful as accretion inhibiting agents, and/or as fluid rheology controlling agents, and/or as filtrate reducing agents, and/or as lubricating agents.

Abstract: Exemplary embodiments of the present technology provide systems and methods for producing power from coalbed methane (CBM) with decreased CO2 emissions. For example, a method of producing power according to an exemplary embodiment includes converting a feedstock from a hydrocarbon source into a gas mixture comprising CO2 and H2. The gas mixture is injected into a coalbed to cause CBM to desorb from the coal and CO2 to adsorb onto the coal. The hydrocarbon source is separate from the coalbed, i.e., does not exchange hydrocarbons with the hydrocarbon source. A gas mixture is produced from the coalbed, wherein the produced gas mixture includes H2 and CH4. The gas mixture may be combusted to generate power, while releasing lower amounts of CO2 than would be released from the combustion of pure CH4.

Abstract: A method for producing hydrocarbons from subsurface formations at different depths is first provided. In one aspect, the method includes the step of heating organic-rich rock, in situ, within a subsurface formation at a first depth. The result of the heating step is that at least a portion of the organic-rich rock is pyrolyzed into hydrocarbon fluids. Preferably, the organic-rich rock of the subsurface formation of the first depth is oil shale. The method also includes providing at least one substantially unheated zone within the formation of the first depth. In this way, the organic-rich rock in that zone is left substantially unpyrolyzed. The method further includes drilling at least one production well through the unheated zone, and completing the at least one production well in a subsurface formation at a second depth that is deeper than the first depth. Thereafter, hydrocarbon fluids are produced through the at least one production well.

Abstract: A plunger lift production system uses a production string including a bottom hole assembly, a production tubing having an inside diameter and including a safety valve having an inside diameter, and a plunger with an outside diameter which closely matches the inside diameter of the safety valve, and an expandable lug and pad assembly, which when expanded closely matches the inside diameter of the production tubing, and when not expanded closely matches the inside diameter of the safety valve.

Abstract: The present invention relates to a drilling composition comprising: I) an organic phase comprising components: i. from about 20 wt. % to about 99.999 wt. %, based on the total weight of components i. and ii., of at least one linear or branched, cyclic or non-cyclic, saturated hydrocarbon; ii. from about 0.001 wt. % to about 25 wt. %, based on the total weight of components i. and ii., of at least one ester; II) from 0 to about 50 wt. %, based on the total weight of the composition, of water or aqueous phase; III) from 0 to about 60 wt. %, based on the total weight of the composition, of at least one additive, wherein the sum of the weight components I) to III) is 100 wt. %, to a process for preparation of a drilling composition, to uses of a drilling composition, to a drilling system, to a process for making a borehole, to a process for conveying cuttings, to a process for treating a drill head, to a process for production of at least one of oil and gas.

Abstract: Embodiments described herein use stochastic inversion (460) in lower dimensions to form an initial model (458) that is to be used in higher-dimensional gradient-based inversion (466). For example, an initial model may be formed from 1.5-D stochastic inversions, which is then processed (464) to form a 3-D model. Stochastic inversions reduce or avoid local minima and may provide an initial result that is near the global minimum.

Abstract: A method of inferring gas production utilizing a conduit having an outlet controlled by a valve in communication with a space within a well through which a gas volume is being produced. A selected number of measurements are taken during a selected period of time, with each measurement including closing the outlet valve to allow gas pressure within the conduit to change, sampling the gas pressure within the conduit over a sampling time period, calculating a rate of pressure change from samples taken over the sampling time period, and calculating a rate of gas production in the conduit from the calculated rate of change of pressure, the gas volume, well characteristics and gas properties. The calculated rates of gas production for the selected number of measurements are summed to determine an inferred rate of gas production through the conduit during the selected period of time.

Abstract: A method for utilizing gas produced from an in situ conversion process includes heating an organic-rich rock formation, for example an oil shale formation. The method may include producing a production fluid from the organic-rich rock formation where the production fluid has been at least partially generated as a result of pyrolysis of formation hydrocarbons located in the organic-rich rock formation. The method may include obtaining a gas stream from the production fluid, where the gas stream comprises combustible hydrocarbon fluids. The method may include separating the gas stream into a first composition gas stream and a second composition gas stream, where the composition of the first composition gas stream is a low BTU gas stream maintained in a substantially constant condition and passing the first composition gas stream through a gas turbine to form a gas turbine exhaust stream, where the gas turbine is connected to an electrical generator.

Abstract: The invention disclosed provides a drive head assembly for a fluid conveyor system that propels a fluid entraining conveyor through a well bore to carry fluids to the surface. The invention is comprised of a pair of synchronized follower wheels connected to a set of counter rotating sheaves. A fluid entraining conveyor is wrapped in a “figure-8” conveyor path around the sheaves in a plurality of coaxial grooves and around a distal sheave located in the fluid in the well bore. The coaxial grooves incorporate a unique shape which in conjunction with the wrap pattern provide improved tractive qualities and thus reduce tension in the conveyor and increase the durability of the conveyor. The conveyor can run at increased speeds and with no tension on the downward portion of the conveyor resulting in higher efficiency and less down time due to breakage.

Abstract: Method for simultaneous full-wavefield inversion of gathers of source (or receiver) encoded geophysical data to determine a physical properties model (118) for a subsurface region, especially suitable for surveys where fixed receiver geometry conditions were not satisfied in the data acquisition. Simultaneous source separation (104) is performed to lessen any effect of the measured geophysical data's not satisfying the fixed-receiver assumption. A data processing step (106) coming after the simultaneous source separation acts to conform model-simulated data (105) to the measured geophysical data (108) for source and receiver combinations that are missing in the measured geophysical data.

Abstract: Method for simultaneous full-wavefield inversion of gathers of source (or receiver) encoded geophysical data to determine a physical properties model for a subsurface region, especially suitable for surveys where fixed receiver geometry conditions were not satisfied in the data acquisition. First, a shallow time window of the data (202) where the fixed receiver condition is satisfied is inverted by simultaneous encoded (203) source inversion (205). Then, the deeper time window of the data (208) is inverted by sparse sequential source inversion (209), using the physical properties model from the shallow time window (206) as a starting model (207). Alternatively, the shallow time window model is used to simulate missing far offset data (211) producing a data set satisfying the stationary receiver assumption, after which this data set is source encoded (212) and inverted by simultaneous source inversion (214).

Abstract: A device and method can detect, and also break, an occurrence of gas lock in an electrical submersible pump assembly in a well bore based upon surface or downhole data without the need for operator intervention. To detect an occurrence of gas lock, an instantaneous value is monitored using a sensor. Then a controller compares the instantaneous value to a threshold value over a predetermined duration to thereby detect the occurrence of gas lock in the electrical submersible pump assembly. Sensors can include, for example, a differential pressure gauge, a pressure gage located in a pump stage located toward the inlet, a fluid temperature sensor located toward the discharge, a free gas detector located near the pump discharge, an electrical resistivity gage, a flow meter located within surface production tubing, and a vibration sensor attached to a tubing string to measure a vibration signature.