Abstract: Methods of improving the pressure containment integrity of subterranean well bores are provided. The methods include pumping a fracture sealing composition into the well bore that rapidly converts into a high friction pressure sealing composition which is impermeable, deformable, extremely viscous and does not bond to the faces of fractures. Thereafter, the fracture sealing composition is squeezed into one or more natural fractures or into one or more new fractures formed in the well bore to thereby increase the pressure containment integrity of the well bore. The methods also include the prediction of the expected increase in pressure containment integrity.

Abstract: Methods of improving the pressure containment integrity of subterranean well bores are provided. The methods include pumping a fracture sealing composition into the well bore that rapidly converts into a high friction pressure sealing composition which is impermeable, deformable, extremely viscous and does not bond to the faces of fractures. Thereafter, the fracture sealing composition is squeezed into one or more natural fractures or into one or more new fractures formed in the well bore to thereby increase the pressure containment integrity of the well bore. The methods also include the prediction of the expected increase in pressure containment integrity.

Abstract: Methods of improving the pressure containment integrity of subterranean well bores are provided. The methods include pumping a fracture sealing composition into the well bore that rapidly converts into a high friction pressure sealing composition which is impermeable, deformable, extremely viscous and does not bond to the faces of fractures. Thereafter, the fracture sealing composition is squeezed into one or more natural fractures or into one or more new fractures formed in the well bore to thereby increase the pressure containment integrity of the well bore. The methods also include the prediction of the expected increase in pressure containment integrity.

Abstract: A downhole pressure transmitter apparatus and method of making the same. A pressure fitting can be provided in association with a tube formed into a spiral shape. One end of said tube is sealed and the other end of said tube is affixed to said pressure fitting. As the tube is exposed to a differential pressure, said tube unwinds, thereby creating a rotary motion that is proportional and linear to said differential pressure sensor, thereby providing an indication of pressure within a downhole environment.

Abstract: Methods and systems for reverse-circulation cementing in subterranean formations are provided. An example of a method is a method of cementing casing in a subterranean well bore, comprising inserting a casing into the well bore, the casing comprising a casing shoe; equipping the casing with a well head, and a casing inner diameter pressure indicator; flowing an equilibrium fluid into the well bore; flowing a cement composition into the well bore after the equilibrium fluid; determining from the well-bore pressure indicator when the well bore pressure has reached a desired value; discontinuing the flow of cement composition into the well bore upon determining that the well bore pressure has reached a desired value; and permitting the cement composition to set in the subterranean formation. Examples of systems include systems for cementing casing in a well bore.

Abstract: A multi-purpose downhole tool comprising packers for isolating an interval of a downhole formation traversed by a borehole to form a packed-off interval annulus. The tool further comprises a reversible pump and more than one interval access port located between the packers. The ports provide fluid communication with fluid in the packed-off interval annulus. The tool further comprises a fluid conduit system and valves for controlling fluid communication between the interval access ports and the reversible pump. The multi-purpose tool is capable of pumping from the packed-off interval annulus as well as pumping into or “through” the packed-off interval annulus for determining formation pressures as well as introducing well enhancement fluids downhole.

Abstract: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud. The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.

Abstract: A method of determining the supercharge pressure in a formation intersected by a borehole having a wall, the method comprising disposing a formation pressure test tool into the borehole having a probe for isolating a portion of the borehole. The method further comprises extending the probe into sealing contact with the borehole wall. The method further comprises performing at least one drawdown test with the formation pressure test tool. The method further comprises modeling the supercharge pressure of the formation using the dynamic properties of the mudcake. The method further comprises determining the supercharge pressure of the formation using the supercharge pressure model. The formation pressure test tool may be conveyed into the borehole using wireline technology or on a drill string. Using the supercharge pressure, the drawdown test may be optimized, the characteristics of the drilling fluid altered, or the measurements of other sensors adjusted.

Abstract: This invention is generally directed towards a system designed to assist the rig operator by alerting him/her that the air pressure is too low to be using the drum clutch, to provide a log for studies on rig operation technique, and to provide a training tool for rig operators. If the pressure on the clutch bladder is above a predetermined range, the clutch is allowed to engage. If the signal is below the range, the clutch is assumed to have not been engaged. If the signal is within the range, the clutch is not allowed to engage and the rig operator is notified of the problem.

Abstract: A method of testing a downhole formation using a formation tester on a drill string. The formation tester is disposed downhole on a drill string and a formation test is performed by forming a seal between a formation probe assembly and the formation. A drawdown piston then creates a volume within a cylinder to draw formation fluid into the volume through the probe assembly. The pressure of the fluid within the cylinder is monitored. The formation test procedure may then be adjusted. The test procedure may be adjusted to account for the bubble point pressure of the fluid being monitored. The pressure may monitored to verify a proper seal is formed or is being maintained. The test procedure may also be performed by maintaining a substantially constant drawdown rate using a hydraulic threshold or a variable restrictor.

Abstract: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a probe and a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud; The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.

Abstract: The apparatus includes a pump for circulating pressurized fluid in a wellbore. A control device controls the pump which a conduit interconnects to the wellbore. A downhole transducer detects changes in fluid pressure at a downhole location and generates signals accordingly. A processor generates actuator commands based on the signals. Actuators activate a downhole tool based on the actuator command. A modulating valve modulates the fluid pressure. A remote transducer detects the pressure remotely from the downhole transducer. The control device causes the pump to generate acoustic signals in the fluid via wave forms which the downhole transducer detects. The modulating valve generates wave forms in the fluid. The control device sends control signals via the fluid to the downhole transducer. Consequently the processor actuates the tools. Following correct actuation the modulating valve generates signals via pressure changes which the remote transducer receives to indicate successful tool deployment.

Abstract: A method for determining formation fluid pressure in earth formation surrounding a borehole wall uses a downhole probe coupled to a variable-volume cavity. The probe is driven into contact with formation at the borehole wall. The method includes expanding the volume of the cavity during a first period of time to establish fluid communication between tool fluid and formation fluid, by withdrawing a minimal amount of fluid from the formation. During a second period of time the tool pressure is allowed to equilibrate to formation pressure. When pressure equilibrium is established, formation fluid pressure is set equal to tool pressure. A preferred embodiment includes terminating expanding the volume of the cavity on detecting a break in the mud cake seal.

Abstract: Methods and apparatus for rapidly measuring pressure in earth formations are disclosed. According to a first embodiment of the apparatus, a probe is provided with a movable piston having a sensor built into the piston. According to a second embodiment of the apparatus, the pressure sensor is mounted adjacent to or within the piston cylinder and a fluid pathway is provided from the sensor to the interior of the cylinder. Methods of operating the first and second embodiments include delivering the probe to a desired location in a borehole, setting the probe against the formation, and withdrawing the piston to draw down fluid for pressure sensing. A third embodiment of the probe is similar to the second but is provided with a spring loaded metal protector surrounding the cylinder and an annular rubber facing. The third embodiment is preferably used in a semi-continuous pressure measuring tool or an LWD tool having a piston controlled bowspring and a piston controlled articulated member carrying the probe.

Abstract: An apparatus for determining fluid-pressure diffusivity in a borehole (12) in a formation (10) includes an electrode (16) and a strain measuring device (18),(20) (or a particle velocity measuring device (18),(20) or a particle acceleration measuring device (18),(20)) disposed a fixed distance from the electrode (16). The electrode (16) injects an electrical current into a point on a wall of the borehole (12). The strain measuring device (18),(20) measures strain (or the particle velocity measuring device (18),(20) measuresd particle velocity or the particle acceleration measuring device (18),(20) measures particle acceleration) at the fixed distance from the point of injection of the electrical current over time. The fluid-pressure diffusivity is determined based on the measured strain (or measured particle velocity or measured particle acceleration) over time.

Abstract: A method of stimulating an entire target formation of an oil or gas well during fluid treatment is obtained by dividing the target formation into intermediate zones and initiating stimulation in each intermediate zone. Once stimulation is initiated in each intermediate zone, ball sealers are used to block the casing perforations at the intermediate zone and divert fluids to another intermediate zone. After stimulation has been initiated in all intermediate zones, the ball sealers are removed from the perforations and treatment of the entire target formation is conducted.

Abstract: A method of predicting the failure of a rock formation surrounding a subterranean cavity, including a measuring set of parameters relating to pressure conditions and stresses in the rock formation surrounding the cavity; using the set of parameters to determine a rock strength; determining a first characteristic length relating to the size of the cavity; determining a second characteristic length relating to the grain size of the rock formation surrounding the cavity; using the first and second characteristic lengths to determine a correction for the rock strength; correcting said rock strength; and using a failure criterion and the corrected rock strength to predict a condition under which the rock formation is expected to produce debris. The results of the prediction can be used to monitor wellbore stability while drilling or optimize the production parameters for a hydrocarbon reservoir.

Abstract: The consequences of any failure of a blow out preventer assembly to operate correctly in an emergency can be far reaching. Thus, there is provided an apparatus for registering parameters in the bore of a member which is, in use, connected to a pressurised housing, the apparatus comprising: an electro-control package for attachment, in use, to the member; a test assembly placed, in use, in the member; the electro-control package and the test assembly having means for sending signals to and receiving signals from one another.

Abstract: A method for determining the maximum and minimum horizontal stresses of formations surrounding a borehole includes the following steps: suspending a logging device in the borehole; transmitting sonic energy from the logging device to establish flexural waves in the formations; receiving, at the logging device, sonic energy from the flexural waves, and producing, from the received sonic energy, measurement signals at a number of frequencies; determining, at the number of frequencies, the fast and slow flexural wave velocities in the formations, to obtain fast and slow flexural velocity dispersions; establishing a model of formation stresses in which stresses of a loaded state are represented by the sum of an omnidirectional hydrostatically loaded mean reference stress, a vertical stress perturbation, and maximum and minimum horizontal stress perturbations; establishing an inversion model that includes inputs from the fast and slow flexural velocity dispersions and also includes unknown horizontal perturbations

Abstract: A method and apparatus is provided to collect downhole data during a drilling operation via a downhole tool. A differential pressure is created by the difference between internal pressure of fluid passing through the downhole tool and the annular pressure in the wellbore. The apparatus includes a drill collar connectable to the downhole drilling, and has an opening extending into a chamber therein. A piston is positioned in the chamber and has a rod extending into the opening. The piston is movable between a closed position with the rod filling the opening, and an open position with the rod retracted into the chamber to form a cavity for receiving downhole fluid. A sensor is positioned in the rod for collecting data from fluid in the cavity. The apparatus may also be provided with a probe and/or hydraulic circuitry to facilitate the collection of data.

Abstract: A non-electric down-hole formation pressure monitoring system utilizing a typical down-hole chemical injection system for pressure data acquisition used with surface computer integration to produce an accurate picture of formation pressure variations utilizing pressure differentials across a pressure balanced valve located adjacent the chemical injection orifice. Computer controlled manipulation of the injection pump pressure maintains a constant differential pressure across the pressure balance valve thus tracking the well formation pressure deviations. The surface computer monitors pump noise, plumbing noise due to vibration, etc., temperature, and fluid and/or gas coefficients, and compensates for any adverse effects that may affect the accuracy of the formation pressures. Down-hole pressure monitoring is achieved in chemical injection or dedicated pressure-monitoring mode with only minor surface adaptations to the well chemical injection pump skid.

Abstract: A well pressure and temperature measurement system and method are provided. In a described embodiment, a sensor system includes multiple strain sensors attached to a structure which changes dimensionally in response to well pressure and temperature changes. The strain sensors may be fiber optic sensors. The structure may be tubular and the strain sensors may detect axial and hoop strains in the structure.

Abstract: A Vadose Zone Water Fluxmeter (WFM) or Direct Measurement WFM provides direct measurement of unsaturated water flow in the vadose zone. The fluxmeter is a cylindrical device that fits in a borehole or can be installed near the surface, or in pits, or in pile structures. The fluxmeter is primarily a combination of tensiometers and a porous element or plate in a water cell that is used for water injection or extraction under field conditions. The same water pressure measured outside and inside of the soil sheltered by the lower cylinder of the fluxmeter indicates that the water flux through the lower cylinder is similar to the water flux in the surrounding soil. The fluxmeter provides direct measurement of the water flow rate in the unsaturated soils and then determines the water flux, i.e. the water flow rate per unit area.

Abstract: A method of determining an in situ PVT property of a hydrocarbon reservoir fluid that is present in a hydrocarbon-bearing formation layer traversed by a borehole, which method involves the steps of: a) calculating along the hydrocarbon-bearing formation layer the pressure gradient; and b) determining the in situ PVT property from the pressure gradient using an empirical relation that had been obtained by fitting a curve (11) through previously obtained data points (12, 13, 14) having the measured PVT property as a function of the pressure gradient.

Abstract: Surface-mounted traffic monitoring sensors that do not require substantial disruption to traffic flow to install or maintain, and that do not substantially degrade the physical integrity of the road. Pneumatic road-tube wedges and surface-mount inductive blades detect wheel-spikes and/or inductive signatures in both fixed and portable installations, single or multi-lane roadways, and provides accurate vehicle speed, volume, occupancy, turning movement counts, weaving sections, classification, re-identification, travel-time, origin and destination, lane-keeping variation, speed-variation, angle-of-attack, and vehicle weight and load distribution. This data is useful to infrastructure planners, traffic-flow modelers, to enhance the safety of work-zone crews, law enforcement, and for real-time traffic operations, etc.

Abstract: The outlet pressure of a pump that fluctuates rapidly, as is typical of high pressure multiplex pumps, is sensed in a pressure line leading from the main flow line to a damping mechanism. The damping mechanism comprises a pair of small spaced openings, which are preferably adjustable in size. The damping mechanism is ideally a pair of needle valves placed in series so the pressure downstream of the second needle valve fluctuates considerably less than upstream of the first needle valve. The damped pressure is sensed to provide an input to real time graphs showing various pertinent pressure measurements involving the application of pressure, e.g. to monitor downhole tools in hydrocarbon wells. The downhole tools may be fluid driven motors, whipstocks, packers, wiper plugs and the like. In the case of fluid driven or mud motors, a base line pressure taken when the motor is idling is compared to the pressure when the motor is drilling to detect the onset of motor stall.

Abstract: A system is described for controlling the flow of a sample fluid through a substrate having first and second surfaces and at least one area with a plurality of through-going capillary channels. The system comprises a housing having a chamber for receiving the substrate and a pressure differential generator capable of generating and maintaining a pressure difference over the substrate.

Abstract: For collecting data from a water well, down-hole sensors are housed in modules. The modules are arranged to be screwed together in-line to form a vertical string. Mechanically, the modules are secured to each other only by the screw connection. Data is transmitted to the surface on a 2-wire cable, there being no other electrical connection between the modules and the surface. The modules are connected in multi-drop configuration to the 2-wire cable. Data is transmitted using time-division multiplexing.

Abstract: The outlet pressure of a pump that fluctuates rapidly, as is typical of high pressure multiplex pumps, is sensed in a pressure line leading from the main flow line to a damping mechanism. The damping mechanism comprises a pair of small spaced openings, which are preferably adjustable in size. The damping mechanism is ideally a pair of needle valves placed in series so the pressure downstream of the second needle valve fluctuates considerably less than upstream of the first needle valve. The damped pressure is sensed to provide an input to real time graphs showing various pertinent pressure measurements involving the application of pressure, e.g. to monitor downhole tools in hydrocarbon wells. The downhole tools may be fluid driven motors, whipstocks, packers, wiper plugs and the like. In the case of fluid driven or mud motors, a base line pressure taken when the motor is idling is compared to the pressure when the motor is drilling to detect the onset of motor stall.

Abstract: Resonant sensor with optical excitation and monitoring device using this sensor. This sensor comprises a doped silicon resonator (4) to absorb radiation (Re) with wavelength longer than 1100 nm and may be used for example to monitor the pressure in an oil well.

Abstract: An apparatus for non-intrusively sensing fluid flow within a pipe is provided. The apparatus includes a first sensing array for sensing acoustic signals traveling at the speed of sound through fluid flow within the pipe, a second sensing array for sensing local pressure variations traveling with the fluid flow, and a housing attached to the pipe for enclosing the sensing arrays. The first sensing array includes a plurality of first optical pressure sensors and the second sensing array includes a plurality of second optical pressure sensors.

Abstract: A downhole sub for instrumentation, such as a fiber optic sensor. The sub is configured to be connected to a string of pipe, such as a string of tubing. The sub first comprises an essentially concentric tubular body. The tubular body has an inner diameter that generally conforms to the inner diameter of the tubing string. A recess is formed within the wall of the tubular body. Next, the sub comprises a gauge housing that is received within the recess of the tubular body. The gauge housing includes a plate portion that is exposed to fluids within the production tubing. The gauge housing further includes a side bore that receives a sensor. One or more gauge housing ports are pre-fabricated into the gauge housing to provide fluid communication between the inner bore of the production tubing and the side bore of the gauge housing. The entire sub is preferably self-contained without any elastomers or metal-to-metal seals.

Abstract: A method for measuring a downhole formation pressure is disclosed which includes lowering a formation testing tool to a desired measuring position in a well borehole. Then a nozzle in the tool is extended so that the nozzle extends through the mud cake layer on a surface of a formation, forming a seal between the mud cake layer and a sealing surface of the nozzle. In an embodiment of the invention, the nozzle has a porous tip that extends into the invaded zone beyond the mudcake layer and is exposed to the formation pressure. In an alternate embodiment, the nozzle has a retractable tip that retracts into the nozzle. The nozzle and retractable tip are positioned in the mudcake and the retractable tip is retracted into the nozzle. The formation pressure is then communicated through the nozzle to a pressure sensor operatively connected to the nozzle.

Abstract: A method and apparatus for measuring the pressure of a formation penetrated by a wellbore is provided. A downhole tool is positioned in the wellbore and a probe is extended therefrom into sealing engagement with the formation. A piston in the probe is retracted therein where by a cavity is defined for receiving a fluid from the formation. A pressure underbalance in the cavity draws fluid from the formation into the cavity. An oscillator may be used to fluctuate the flow of fluid into the cavity. A pressure gauge is used to measure the pressure of fluid in the cavity.

Abstract: An apparatus and methods for determining in situ pore fluid and soil properties at a particular subsurface location are disclosed. In one embodiment, the apparatus comprises a penetrating tip member configured to penetrate soil. The apparatus further comprises an attachment module coupled to the penetrating tip member. The attachment module includes at least one mandrel that includes a piezo sensor. An in situ measurement of pore pressure is obtained by the piezo sensor at a depth that corresponds to the location of the at least one mandrel on the attachment module.

Abstract: The invention relates to a DFB fiber laser sensor (1). A measurement quantity makes it possible to induce a linear birefringence between mode pairs of the laser-amplifying fiber (2) and to measure an associated beat frequency (&Dgr;&ngr;1, &Dgr;&ngr;2, &Dgr;&ngr;3). According to the invention, the laser-amplifying fiber (2) has a nonrotationally symmetrical structure, so that it is possible to detect isotropic pressures p, acoustic waves or chemical substances that can be added radially to the laser-amplifying fiber (2). In a second aspect of the invention, an emission wavelength range and parameters (a, b, &Dgr;N) of the laser-amplifying fiber (2) and also a grating period L of the fiber Bragg grating resonator (3) are coordinated with one another such that at least two different spatial modes (LP01, LP11even, LP11odd, LP21even) are propagatable and it is possible to measure beat frequencies (&Dgr;&ngr;1, &Dgr;&ngr;2, &Dgr;&ngr;3) between oscillatory longitudinal laser modes assigned to them.

Abstract: Methods and apparatus for rapidly measuring pressure in earth formations are disclosed. According to a first embodiment of the apparatus, a probe is provided with a movable piston having a sensor built into the piston. According to a second embodiment of the apparatus, the pressure sensor is mounted adjacent to or within the piston cylinder and a fluid pathway is provided from the sensor to the interior of the cylinder. Methods of operating the first and second embodiments include delivering the probe to a desired location in a borehole, setting the probe against the formation, and withdrawing the piston to draw down fluid for pressure sensing. A third embodiment of the probe is similar to the second but is provided with a spring loaded metal protector surrounding the cylinder and an annular rubber facing. The third embodiment is preferably used in a semi-continuous pressure measuring tool or an LWD tool having a piston controlled bowspring and a piston controlled articulated member carrying the probe.

Abstract: A pressure sensing unit has a pressure responsive member, a pressure sensor, and a hydraulic connector hydraulically connecting the pressure responsive member with the pressure sensor to produce an indication of sensed pressure. The hydraulic connector includes a tubular member and a longitudinal insert in the tubular member with hydraulic fluid in the tubular member between the insert and the member. The tubular member, the insert and the hydraulic fluid and the dimensions of the tubular member and the insert are such that the hydraulic fluid transmitted to the pressure sensor is substantially independent of temperature changes.

Abstract: A method and apparatus is provided to determine downhole pressures, such as annular pressure and/or pore pressure, during a drilling operation. A bottom hole assembly (BHA) of a downhole tool includes one or more pressure equalizing assemblies capable of registering the pore pressure when the BHA is at rest and in contact with the wellbore, and annular pressure of a wellbore when it is not. Wellbore fluid is permitted to enter the pressure equalizing assembly and register an annular pressure measurement. Once the BHA comes into contact with the wellbore and to rest, fluid communication is established between the pressure equalizing assembly and the formation to generate a pore pressure measurement. The pressure equalizing assembly includes a sliding valve selectively moveable between an open and closed position in response to operation of the BHA so that the desired pressure measurement may be taken.

Abstract: A method and apparatus is provided to determine downhole pressures, such as annular pressure and/or pore pressure, during a drilling operation. A downhole drilling tool includes at least one conduit and a corresponding gauge. The conduit is positioned in the downhole tool and has an opening adapted to receive downhole fluids. The conduit is positionable in fluid communication with one of the wellbore and the formation whereby pressure is equalized therebetween. The gauge is provided for measuring the pressure in the conduit.

Abstract: A well pressure and temperature measurement system and method are provided. In a described embodiment, a sensor system includes multiple strain sensors attached to a structure which changes dimensionally in response to well pressure and temperature changes. The strain sensors may be fiber optic sensors. The structure may be tubular and the strain sensors may detect axial and hoop strains in the structure.

Abstract: A carrier apparatus for connection with a pipe string for use in transporting at least one gauge downhole through a borehole. The apparatus includes a tubular body for connection with the pipe string having a bore for conducting a fluid therethrough and an outer surface, wherein the outer surface has at least one longitudinal recess formed therein. Further, at least one insert defining an internal chamber for receiving a gauge is mounted with the body such that at least a portion of the insert is receivable within the recess for engagement therewith. The apparatus also includes an interlocking interface comprised of the engagement between the insert and the recess, wherein the interlocking interface is configured such that the insert inhibits radial expansion of the body adjacent the recess. Finally, at least one passage provides fluid communication between the gauge and one of the bore of the body and the borehole.

Abstract: A system of measuring properties, such as pressure, and transmitting measurements in a subterranean well. In a described example, a valve system includes a valve having a closure member. A sensor senses a pressure differential across the closure member. A tool positioned in the valve transmits power to the valve to operate the sensor, and the sensed pressure differential is transmitted from the valve to the tool.

Abstract: A method for determining the liquefaction tendency of a water saturated soil is provided in which a driven or self boring probe with a plurality of expanding and contracting bladders imposes a cyclic shear stress reversal on a body of soil in situ, and from the measurement of pore water pressure, the liquefaction potential of the soil can be quantified. A pore water pressure increase during cyclic shear stress reversals indicates a contractive soil which has the potential to liquefy. The method can also quantify the potential of electro-osmosis in preventing soil liquefaction, by energizing a group of at least three electrodes by a d-c power source during the potential onset of liquefaction, and measure the reduction in pore water pressure during subsequent repeated shear stress reversals imposed on the soil by the device.

Abstract: A method for assessing the fracture pressure closure is proposed. This method includes first injecting a fluid into the formation at a first generally constant rate Q to create a fracture, and then, dropping the pumping rate to significantly smaller feed rate q so that the volume of the fracture becomes constant, in other words. As the fracture volume becomes constant at equilibrium, the well is shut-in. The wellbore pressure is monitored and the closure pressure is determined from the analysis of the wellbore pressure using a time-function of the dimensionless “shut-in” time, defined as the ratio of time since shutting to pumping time. This method provides a way of estimating the friction component of the monitored wellbore pressure due to the fracture tortuosity and friction.

Abstract: A hydraulic strain sensor for use with a downhole tool includes a housing having two chambers with a pressure differential between the two chambers. A mandrel is disposed in the housing. The mandrel is adapted to be coupled to the tool such that the weight of the tool is supported by the pressure differential between the two chambers. A pressure-responsive sensor in communication with the one of the chambers is provided to sense pressure changes in the chamber as the tool is accelerated or decelerated and to generate signals representative of the pressure changes.

Abstract: A pressure self-compensating tensiometer and method to in situ determine below grade soil moisture potential of earthen soil independent of changes in the volume of water contained within the tensiometer chamber, comprising a body having first and second ends, a porous material defining the first body end, a liquid within the body, a transducer housing submerged in the liquid such that a transducer sensor within the housing is kept below the working fluid level in the tensiometer and in fluid contact with the liquid and the ambient atmosphere.

Abstract: A control system and method for determining optimal fluid injection pressure is based upon a model of a growing hydrofracture due to waterflood injection pressure. This model is used to develop a control system optimizing the injection pressure by using a prescribed injection goal coupled with the historical times, pressures, and volume of injected fluid at a single well. In this control method, the historical data is used to derive two major flow components: the transitional component, where cumulative injection volume is scaled as the square root of time, and a steady-state breakthrough component, which scales linearly with respect to time. These components provide diagnostic information and allow for the prevention of rapid fracture growth and associated massive water break through that is an important part of a successful waterflood, thereby extending the life of both injection and associated production wells in waterflood secondary oil recovery operations.

Abstract: A method for measuring a downhole formation pressure is disclosed which includes lowering a formation testing tool to a desired measuring position in a well borehole. Then a nozzle in the tool is extended so that the nozzle extends through the mud cake layer on a surface of a formation, forming a seal between the mud cake layer and a sealing surface of the nozzle. In an embodiment of the invention, the nozzle has a porous tip that extends into the invaded zone beyond the mudcake layer and is exposed to the formation pressure. In an alternate embodiment, the nozzle has a retractable tip that retracts into the nozzle. The nozzle and retractable tip are positioned in the mudcake and the retractable tip is retracted into the nozzle. The formation pressure is then communicated through the nozzle to a pressure sensor operatively connected to the nozzle.

Abstract: The invention is an apparatus for measuring pressure, which comprises a pressure communicating device (3) for location at a point (4) at which pressure is to be measured, a primary tube (1) containing a fluid for linking the pressure communicating device (3) to a control point (9) where the pressure information is required, a sealing device for sealing the primary tube (1) so as to form a closed system when the pressure communicating device (3) is closed, a pressure control device (6) for changing the pressure of the fluid within the primary tube (1), a volume measuring device (8) for measuring changes in the volume of the fluid within the primary tube (1) as the pressure of the fluid is varied, a pressure measuring device (7) for measuring the pressure of the fluid at some point within the fluid, and device remote from the control point (9), and a transmitter device for transmitting pressure information from the pressure measuring device to the control point (9).