Abstract: A downhole sensor position adjustment device on a downhole sensor assembly comprising a set of centralizers and a sensor array coupled to an adjustable framework radially positionable by an actuator. The actuator includes an extend-retract mechanism to radially position the sensor array a predetermined radial distance to an inner surface of a casing. A controller communicatively coupled to the extend-retract mechanism is configured to actuate the extend-retract mechanism. A positioning sensor provides feedback of the predetermined radial distance of the sensor array to the inner surface of the casing.

Abstract: A gyroscope assembly is maintained in a park position during drilling activities. In the park position, a sensitive axis of a gyroscope in the gyroscope assembly is perpendicular or approximately perpendicular to a longitudinal axis of a downhole tool. Maintaining the park position during drilling activities reduces the drift bias caused by overloading the input signal of the gyroscope due to rotation of the downhole tool.

Abstract: A rotary steerable tool for directional drilling includes a tool body with a flowbore, a plurality of extendable members, each independently movable between an extended position and a retracted position, and a plurality of actuation devices, each being independently operable to control a respective one of the extendable members.

Abstract: A casing pipe extends in a vertical direction, and two adjacent casing pipes are connected by a plurality of link mechanisms; the link mechanism includes two supports, the two supports are hinged by a first pin to form a hinged portion, an upper end and a lower end of the link mechanism are hinged to two adjacent casing pipes by second pins separately, a sensor is fixed to the link mechanism, and the link mechanism has an initial state of extending in the vertical direction and an extending state in which the hinged portion extends outwards to be located on an outer side of the casing pipe; a driving mechanism drives a push portion to move towards the link mechanism; and a downward pressing apparatus is used for pressing a top end of the topmost casing pipe downwards to push the hinged portion into a side wall of the borehole.

Abstract: A downhole sensing device deployment control apparatus (10) includes means to control speed of the sensing device progressing within a borehole associated with a drilling operation. A mechanical, electrically powered and/or hydro-dynamic drag/damping means/device (12) can be provided as part of the control apparatus to control speed of deployment down the borehole. The drag device (12) can have a plurality of wheels or rollers to contact an internal bore of an inner pipe of a drill string. Rotation control means (24), (26) can be provided to control an amount of rotation and/or direction of rotation of the wheels or rollers relative to travel of the sensing device within the borehole. Valving (60) can be provided. A two stage (dual) flow/pressure control valve (100) can be provided. A sensing device (release 216) and downhole position latch (202) can be provided. The sensing device can be pumped into the borehole, such as by compressed air.

Abstract: Systems and methods are provided for estimating and/or using drilling efficiency parameters of a drilling operation. A method for estimating drilling efficiency parameters may include using a borehole assembly that includes a drill bit to drill into a geological formation. A number of measurements of weight-on-bit and torque-on-bit may be obtained during a period in which weight-on-bit and torque-on-bit are non-steady-state. The measurements of weight-on-bit and torque-on-bit may be used to estimate one or more drilling efficiency parameters relating to the drilling of the geological formation during the period.

Abstract: Logging-while-drilling (LWD) tools may include multiple instruments interleaved into a compact configuration in a single drill string section that may be capable of nuclear magnetic resonance, resistivity, porosity, gamma density measurements, or any combination thereof. For example, a LWD tool may include a drill collar section containing: a nuclear magnetic resonance (NMR) electronics module and an NMR sensor module interleaved with a nuclear source and at least one nuclear detector.

Abstract: A method and system for detecting mercury in a hydrocarbon-containing fluid stores a sample of the hydrocarbon-containing fluid in a first reservoir. A liquid phase reagent solution is stored in a second reservoir. The liquid phase reagent solution includes nanoparticles with an affinity to mercury, wherein the nanoparticles are suspended as a colloid in the liquid phase reagent solution. The sample of the hydrocarbon-containing fluid is delivered from the first reservoir into a first port of a fluidic device while the liquid phase reagent solution is delivered from the second reservoir into a second port of the fluidic device such that the fluidic device produces slug flow. The slug flow is subject to optical analysis that determines concentration of mercury in the sample of the hydrocarbon-containing fluid.

Abstract: An apparatus and method to control and exert a predetermined force back on the wellbore thereby controlling the hydrostatic force on the formation surrounding the well-bore, the inflow of fluids from the surrounding formation and the drilling circulating medium. The apparatus comprises and the method utilizes a pump having at least one pair of intermeshing and opposite-handed helical screws disposed within a chamber for restricting the flow of well bore returns. The speed of the pump may be varied to selectively restrict the flow of well bore returns from the well bore.

Abstract: A drill bit is disclosed that in one embodiment includes a pad configured to extend and retract from a surface of the drill bit, a motor, a linearly movable member coupled to the motor, a hydraulic unit configured to apply force on the pad, and wherein motion of the motor in a first direction causes the linearly movable member in a first direction to cause the hydraulic unit to exert a force on the pad to extend the pad.

Abstract: A borehole logging instrument sonde employs a case in which support electronics including a processor are mounted. A rotatable platform is mounted within the case and carries an inertial measurement unit (IMU) and a roll axis gyroscope. A motor is adapted to rotate the rotatable platform within the case. The processor receives an input from the roll axis gyroscope and provides an output to the motor responsive to the input for control of rotation of the platform to space stabilize and isolate the IMU from the roll of the instrument sonde.

Abstract: A formation tester for use in a subterranean well can include a probe which extends outward into contact with an earth formation, and an adjustable flow control device which limits an extension pressure applied to extend the probe. A method of testing a subterranean formation can include positioning a formation tester in a wellbore, extending a probe of the formation tester outward into contact with the formation, and limiting a force applied by the probe to the formation, the limiting being performed by variable actuation of a flow control device downhole. Another formation tester can include a probe which extends outward into contact with an earth formation, with a force applied by the probe to the formation being remotely adjustable downhole.

Abstract: An apparatus for in situ geophysical sensing includes a sensor for measuring geophysical data and a liquid absorbent member connected to the sensor that expands in response to contacting a liquid and thereby physically couples the sensor to a local sensing environment. The liquid absorbent member may be formed of beads or pellets or powder that includes a liquid absorbent material. The liquid absorbent member may also include a soluble binding agent for binding the beads or pellets or powder into an integral member such as a casing for containing the sensor. A method and system corresponding to the apparatus are also described herein. The apparatus, method and system described herein may be used to improve borehole sensor data quality without adding significant complexity to the borehole sensor deployment process.

Abstract: A multizone testing system (100), for the testing of subterranean layers, comprises an upper subsystem (109) comprising a control station (151), a main isolation packer (113) for isolating the upper subsystem (109) from the lower subsystem (111), a lower subsystem (111) comprising an array of individual apparatuses (116) connected in series, each apparatus (116) being adapted for the testing of one layer and comprising a series of remotely activated tools for hydraulically isolating and testing the corresponding layer and a communication system comprises communication means between the control station (151) and the surface and between the control station (151) and each of the individual apparatuses (116) in order to control the remotely activated tools of the individual apparatuses for sequential testing of the layers.

Abstract: Method and apparatus for forecasting curving of an hydraulic fracture to be initiated in the vicinity of one or more previously placed fractures along a bore hole. Physical parameters that will affect the growth of the hydraulic fracture are received by a dimensionless parameter deriver which derives a series of dimensionless parameters as groupings of the physical parameters that are selected as similarity parameters with respect to the shape of the hydraulic fracture path. The dimensionless parameters may comprise a dimensionless viscosity parameter, a dimensionless confining stress parameter, a coefficient of friction parameter and a dimensionless deviatoric stress parameter. A comparator sequentially compares the determined dimensionless parameters with predetermined threshold values to provide an indication as to possible curving of the hydraulic fracture.

Abstract: A probe for establishing fluid communication between a downhole tool and a subterranean formation is provided. The downhole tool is positioned in a wellbore penetrating the subterranean formation. The probe includes a platform operatively connected to the downhole tool, at least one packer operatively connected to the platform, the packer having at least one hole extending therethrough and at least one embedded member disposed in the packer for enhancing the operation of the packer as it is pressed against the wellbore wall.

Abstract: An apparatus, method and system are provided for characterizing fluid trapped in a subterranean formation using a downhole tool that includes an elongated body and a probe body. The probe body is moveable from and back into the elongated body. The probe body defines a flow line and supports a pressure sensor for measuring fluid pressure in the flow line, a piston and an electrical motor actuator that is adapted to move the piston in order to vary volume of the flow line. The integral electrical motor actuator, piston, pressure sensor and flow line of the probe body can provide for measurement of formation pressure and/or formation mobility.

Abstract: An anti-lock system, device and method for logging a wellbore are presented. The anti-lock system of a downhole tool preferably includes a first arm, a second arm, a pad, a swivel bearing between the first arm and the pad, and an anti-locking device. The first arm has an arm first end connected to the tool body of the downhole tool and an arm second end connected to a first end of the pad. The second arm has an arm first end connected to the tool body of the downhole tool and an arm second end connected to a second end of the pad. The swivel bearing between the first arm and the pad pivotally connects the first arm to the pad. The anti-locking device is coupled to the swivel bearing, and preferably includes an anti-lock biasing member for maintaining a connection between the first arm and the pad at the swivel bearing in an engaged position during normal logging and for allowing the connection to rotate toward a biased position when a binding force is encountered in the arm system.

Abstract: Methods for long-term gravimetric monitoring of carbon dioxide stored in a geological formation are disclosed.

Abstract: A logging tool, toolstring (10), or element (19) comprises a stabilizer including a pair of moveable, rigid, main stabilizer arms (23, 24) that each is pivotably secured adjacent to one another at one end to the logging tool or toolstring. As a result the arms (23, 24) are moveable between a relatively retracted position on the one hand and a relatively advanced position on the other in which the main stabilizer arms diverge from one another and protrude from the logging tool so as to present a pair of main arm free ends (29, 31) that are spaced from an outer surface of the tool and are engageable with a borehole surface. The logging tool (10) or element (19) includes a mechanism for effecting coordinated, powered, linked movement of the main stabilizer arms (23, 24) between the retracted and advanced positions.

Abstract: An acoustic sensing tool for use with a carrier disposed in a wellbore may include a base and a resilient clamp disposed around the base. The clamp may move between a retracted position, in which the clamp interior surface engages the carrier, and an expanded position, in which the clamp exterior surface engages the wellbore. A sensor is coupled to the clamp. An actuator is movable along the base and operably coupled to the clamp. The actuator is operable to move the clamp between the retracted and expanded positions and configured to maintain contact with the clamp in both the retracted and expanded positions so that movement of the actuator in a first direction causes the housing to move to the expanded position, and movement of the actuator in a second, opposite direction causes the housing to move to the retracted position.

Abstract: A logging tool, system and method for logging a wellbore are presented. The logging tool preferably includes at least two arm sets that are positionable on a downhole tool deployable into the wellbore. The two arm sets preferably include a first arm set, a second arm set, and an overlap tool body. The first arm set has at least two azimuthally spaced first arm systems with a sensor pad coupled to two arms. The two arms have an upper connection and a lower connection on a tool body of the downhole tool. The second arm set has at least two azimuthally spaced second arm systems with a sensor pad coupled to two arms. The two arms have an upper connection and a lower connection on the tool body, and wherein the upper connection of the second arm set are longitudinally overlapped between the lower connections of the first arm set. The overlap tool body portion for coupling the upper connection of the second arm set and the lower connections of the first arm set to the downhole tool.

Abstract: A portable monitor used to measure landfill gas and landfill well parameters. The portable monitor includes a control unit and a measuring unit that can communication wirelessly with one another. The control unit and/or measuring unit can includes a heating arrangement to increase the temperature of one or more components in the control unit and/or measuring unit in cold environments.

Abstract: A downhole tool comprising a probe, wherein the probe comprises: a first inlet having an elongated cross-sectional shape, and a second inlet surrounding the first inlet. The downhole tool further comprises at least one pump configured to draw fluid from a subterranean formation through the first and second inlets.

Abstract: A borehole logging tool includes a housing oriented along a longitudinal axis, and a centralizer assembly that positions the housing substantially at the center of the borehole. In one example, the centralizer assembly includes a plurality of centralizer arms radially extendable outward from the longitudinal axis. The borehole logging tool further includes a scanning head that rotates a plurality of scanning sensors axially within the borehole about the longitudinal axis. The scanning head further includes a plurality of linkage arms coupled to the plurality of scanning sensors such that the scanning sensors are radially extendable outward from the longitudinal axis. The borehole logging tool further includes an extension assembly adapted to substantially concurrently control the radial extension of the centralizer arms and the plurality of sensors.

Abstract: A low maintenance adjustable gas trap with a plurality of couplings, each coupling securing to a flow line of a drilling rig; a plurality of hammer unions each engaging a coupling; a plurality of base manifold pipes, each engaging a hammer union; a base manifold flow line engaging the base manifold pipes, a chimney pipe connected to the base manifold flow line with a controllable valve, a reducer connected to the chimney opposite the base manifold flow line; an expansion chamber component connected to the reducer; a restrictor mounted to the expansion chamber component opposite the reducer, wherein the restrictor has a diameter no more than ?rd a diameter of the expansion chamber component; and a conduit connection connected to the restrictor for engaging a conduit to flow a gas sample from the gas trap to a gas analyzer.

Abstract: A jet pump on pipe string and packer, pump body being provided with steplike pass channel embodied therein and communicates with pumped-out medium supplying channel and active medium supplying channel, connected to active nozzle at the output and to annular space. The pumped-out medium-supplying channel connects to the pipe string downstream of steplike channel via return valve. A hollow steplike cylindrical body sealing unit provided with a top part sealing element arranges in said steplike channel. An annular projection supported spring-loaded steplike piston is downstream. The piston lower position closes unit body holes. When the piston is in top position, the channel for supplying medium pumped-out from the well through the unit holes and pump bodies connects to the pipe string downstream of the pump body. The piston and sealing element include coaxial channels therein, used for passing a cable with logging instrument suspended below the pump body.

Abstract: A sonde and an apparatus for the deployment thereof against a well casing is described, the sonde comprising a resilient C-shaped member and at least one sensor.

Abstract: A system and method using inverse-vector processing to iterate through a loop of three steps: set a guide direction, invert opposite vectors, and average vectors to update the guide direction, for smoothing seismic amplitude data. The inverse-vector method can overcome instabilities where the traditional structure-tensor approach fails. The inverse-vector smoothing is simple to implement and more computational efficient. The resultant dips and azimuths are spatially consistent and thus more interpretable and suitable for calculation of curvature and other dip based attributes.

Abstract: A borehole tool, comprises: a tool body; a series of arms connected to the tool body and moveable radially relative thereto; and a series of pads mounted on the arms so as to be pivotable about a radial axis relative to the tool body. By allowing pivoting of the pads about a radial axis, elongate pads can be arranged to provide different circumferential coverage according to the orientation with respect to the longitudinal axis of the borehole.

Abstract: Methods and systems for testing a subterranean formation penetrated by a wellbore are provided. A testing tool has a plurality of packers spaced apart along the axis of the tool, and at least a testing port. The testing tool is positioned into the wellbore and packers are extended into sealing engagement with the wellbore wall, sealing thereby an interval of the wellbore. In some embodiments, the wellbore interval sealed between two packers is adjusted downhole. In one embodiment, the location of the testing port is adjusted between two packers. The methods may be used to advantage for reducing the contamination of the formation fluid by fluids or debris in the wellbore.

Abstract: A borehole seismic acquisition tool configured for release from a stuck position within a borehole having a tool body with at least one sensor package, an anchoring arm, and anchoring arm linkage adapted to connect the anchoring arm to the tool body. The anchoring arm linkage includes a weakpoint mechanism adapted to break in response to a minimum threshold amount of breaking force being applied upon the weakpoint mechanism. The anchoring arm includes a first end adapted for contacting a borehole wall surface and a second end pivotally attached to the anchoring arm linkage. The anchoring arm also includes a movable cam removably secured to the first end via a first connector pin. The cam being at least partially rotatable about the first connector pin and configured and arranged to rotate against the borehole wall by a pulling force at a top portion of the borehole seismic acquisition tool.

Abstract: A formation fluid sample is exposed to a rigidly-supported semi-permeable membrane such as silicone rubber to permit diffusion of gases and vapors from the formation fluid into a vacuum chamber, while at the same time, blocking the passage of any liquids. The membrane-transmitted gas is analyzed in the vacuum chamber by a residual gas analyzer. An ion pump or sorbent is associated with the evacuated chamber to maintain the vacuum. The ion pump or sorbent removes gases and vapors from the chamber that diffuse into the chamber from the reservoir sample that is on the opposite side of the semi-permeable membrane.

Abstract: A formation testing tool is described herein, including a formation probe assembly having an extendable sampling probe surrounded by a cylindrical sleeve. The sleeve is configured to engage a metal skirt having an elastomeric seal pad coupled thereto. The skirt and seal are configured to be field replaceable. The elastomeric pad has a non-planar outer surface which engages a borehole wall in preparation for formation testing. The seal pad may be donut-shaped, having an aperture through the middle of the seal pad. The seal pad and its surface may include numerous different embodiments, including having a curved profile. The seal pad may also include numerous different embodiments of means for coupling the seal pad to the metal skirt. The formation testing tool also includes formation probe assembly anti-rotation means, a deviated non-circular flowbore, and at least one closed hydraulic fluid chamber for balancing fluid pressures.

Abstract: A method and apparatus for sampling formation fluid includes drawing formation fluid from the subterranean formation into the downhole tool and collecting the formation fluid in a sample chamber. An exit flow line is operatively connected to the sample chamber for selectively removing a contaminated and/or clean portion of the formation fluid from the sample chamber whereby contamination is removed from the sample chamber. For example, a clean portion of the formation fluid may be passed to another sample chamber for collection, or a contaminated portion may be dumped into the borehole.

Abstract: Techniques for reduced contamination formation evaluation are provided. The techniques relate to drawing fluid into a downhole tool positionable in a wellbore penetrating a subterranean formation having a virgin fluid and a contaminated fluid therein. Fluid is drawn into at least two inlets for receiving the fluids from the formation. At least one evaluation flowline is fluidly connected to at least one of the inlets for passage of the virgin fluid into the downhole tool. At least one cleanup flowline is fluidly connected to the inlets for passage of the contaminated fluid into the downhole tool. At least one fluid circuit is fluidly connected to the evaluation flowline and/or cleanup flowlines for selectively drawing fluid therein. At least one fluid connector is provided for selectively establishing a fluid connection between the flowlines. At least one sensor is provided for measuring downhole parameters in one of the flowlines.

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: The apparatuses and methods herein relate to techniques for extracting fluid from a subsurface formation. A downhole sampling tool is provided with a probe having an internal wall capable of selectively diverting virgin fluids into virgin flow channels for sampling, while diverting contaminated fluids into contaminated flow channels to be discarded. The characteristics of the fluid passing through the channels of the probe may be measured. The data generated during sampling may be sent to a controller capable of generating data, communicating and/or sending command signals. The flow of fluid into the downhole tool may be selectively adjusted to optimize the flow of fluid into the channels by adjusting the internal wall within the probe and/or by adjusting the flow rates through the channels. The configuration of the internal wall and/or the flow rates may be automatically adjusted by the controller and/or manually manipulated to further optimize the fluid flow.

Abstract: A borehole caliper tool includes a tool body, a bow spring flexibly coupled to the tool body, a target coupled to the bow spring, and an ultrasonic transducer coupled to the tool body, wherein in operation the ultrasonic transducer transmits an acoustic pulse to the target and receives an echo of the acoustic pulse from the target.

Abstract: A system that is usable with a subterranean well that has a casing includes an apparatus that is associated with production of fluid from the well and is located downhole in the well in a passageway of the casing. The system also includes a sensor that is located downhole near the apparatus in the passageway and is adapted to measure a characteristic of the formation fluids and rock located outside of the casing.

Abstract: A sonde and an apparatus for the deployment thereof against a well casing is described, the sonde comprising a resilient C-shaped member (22) and at least one sensor (23).

Abstract: Earth formations are characterized by using an array of electrodes which can measure streaming potentials in the formation, and by interpreting the data obtained by the electrodes. The electrodes are placed on a wireline tool, a LWD tool, or in a fixed manner about a completed wellbore. The measured streaming potentials are generated by drilling with an overbearing pressure, slitting the mudcake in a borehole, acid injection, or any of various other manners which causes fluid movement. The data obtained is interpreted to locate fractures, measure formation permeability, estimate formation pressure, monitor drilling fluid loss, detect abnormal pressure, etc. Particularly, a streaming potential voltage transient having a double peak profile signifies the presence of a formation fracture.

Abstract: The apparatuses and methods herein relate to techniques for extracting fluid from a subsurface formation. A downhole sampling tool is provided with a probe having an internal wall capable of selectively diverting virgin fluids into virgin flow channels for sampling, while diverting contaminated fluids into contaminated flow channels to be discarded. The characteristics of the fluid passing through the channels of the probe may be measured. The data generated during sampling may be sent to a controller capable of generating data, communicating and/or sending command signals. The flow of fluid into the downhole tool may be selectively adjusted to optimize the flow of fluid into the channels by adjusting the internal wall within the probe and/or by adjusting the flow rates through the channels. The configuraton of the internal wall and/or the flow rates may be automatically adjusted by the controller and/or manually manipulated to further optimize the fluid flow.

Abstract: A method and apparatus, for deploying a sensor attached to tubing in a highly deviated or horizontal wellbore, that are characterized by a stationary attachment system that securely fixes a sensor to a tubing string such that the sensor is coupled to the casing regardless of the orientation of the tubing within the wellbore. One preferred embodiment includes a clamp assembly that encloses the sensor and clamps around the cubing string. The clamp assembly further includes a plurality of contact members that provide stable contact points between the well casing and the clamp assembly. The embodiments of the present invention act to maintain the sensor in a stable coupling with the casing without any actuation required for installation.

Abstract: A method for retrieving a formation fluid sample through a cased borehole utilizing a sampling tool. Sampling tool straddle packers are set about a first set of perforations and annular fluid is drained from the isolated zone, through a central conduit in the tool and discharged above or below the packers. Formation fluid is induced to flow into the central conduit and into sample chambers. The packers are unset, the tool moved to the next set of perforations that are azimuthally offset from the first set of perforations and the sampling process repeated, with subsequent samples being placed in separate sample chambers.

Abstract: A Logging-while-Drilling method and apparatus for obtaining information about a formation uses a plurality of rib sets with pad-mounted sensor on one or more selectively non-rotating sleeves attached to a rotating housing that is part of a drilling assembly. The sensors may be density, neutron, NMR, resistivity, sonic, dielectric or any number of other sensors. In an alternative arrangement, the sensors rotate with the drill string.

Abstract: A new class of materials testing apparatus has been invented. Particularly suited to the measurement of fracture and fatigue properties in the extremely strong materials encountered in microelectromechanical systems, material strains well in excess of 1% can be applied pseudostatically, dynamically, or repetitively by these testers. There are no other practical methods to determine these material properties routinely in a process environment, and few alternatives in any circumstances.

Abstract: Initially, signals relating to well bore fluids that are generated from sensors in presently available down-hole logging tools are analyzed and/or interpreted by an electronic circuit in a well logging tool. The interpretation of these signals can be direct, differential, or summation measurements from the sensors. The signal interpretations can be qualitative or quantitative, depending on how the tool is set up or programmed of the electronic circuit. When gas/oil, gas/water, or oil/water contacts are made in the well bore, the circuit will send a signal to a set of electromagnets or a drag mechanism that will momentarily grab the walls of the pipe. This will create a line tension spike on the load cell/weight indicator on the surface, and a well log can be generated to show where these line tension spikes occur, thus indicating the depth of various fluids in the well bore.

Abstract: A distributed pressure monitoring system is disclosed for monitoring formation pressure along substantial lengths of a casing in a borehole. The monitoring system has a communications line connected to surface facilities on one end which leads down the casing on the other end. A plurality of pressure sensors are spaced along the casing, each connected in communication with the communications line. A sensor housing encloses each sensor and an open pressure tentacle is attached to the sensor housing in communication with the pressure sensor. Another aspect of the present invention is a method for simultaneously monitoring the formation pressure in multiple zones of a borehole. The formation pressure is substantially separated from overburden pressure and pressure sensors adjacent selected zones of the formation are substantially isolated by filling the borehole with a cement selected to provide less hydraulic diffusivity than that of the formation.

Abstract: A sidewall tensiometer to in situ determine below-grade soil moisture potential of earthen soil includes, a) a body adapted for insertion into an opening in earthen soil below grade, the body having lateral sidewalls; b) a laterally oriented porous material provided relative to the body lateral sidewalls, the laterally oriented porous material at least in part defining a fluid chamber within the body; c) a pressure a sensor in fluid communication with the fluid chamber; and d) sidewall engaging means for engaging a portion of a sidewall of an earth opening to laterally urge the porous material into hydraulic communication with earthen soil of another portion of the opening sidewall. Methods of taking tensiometric measurements are also disclosed.