Abstract: System for conducting measurements of friction of a chosen material with reduced errors. The system includes a sample holder, a bushing accommodating such holder while permitting reversible repositioning of the holder along a bushing axis, a horizontal force sensor, a vertical force sensor, a sample holder pusher and a subsystem including a linear vertical bearing (disposed in the bushing and separating the holder from the bushing) and/or a horizontally-sliding element between the rod pusher and the vertical force sensor. The subsystem is structured to reduce a rocking motion of the holder in the bushing caused by a relative motion between the sample and an auxiliary body brought in contact with the sample. The method for performing measurements with such system.

Abstract: A wellbore fluid monitoring system includes a housing, an air flow sensor, a first sealing element, a second sealing element and a sealing unit. The housing is configured to be securely disposed in a portion of an annulus within a bell nipple below a rotary table of a wellbore drilling assembly. The annulus is formed by a drill string of the wellbore drilling assembly and an inner wall of a wellbore being drilled by the wellbore drilling assembly. The housing includes a hollow internal chamber. The air flow sensor is disposed within the hollow internal chamber. The air flow sensor is configured to sense flow of air through the hollow internal chamber. The first sealing element is attached to a first end of the housing. The second sealing element is attached to a second end of the housing. The sealing unit is disposed in the portion of the annulus. The sealing unit is connected to the housing, the first sealing element and the second sealing element.

Abstract: A method and apparatus for determining a gas influx into a wellbore. A work string defining an inner bore area and an annulus area, with a pair of inner bore sensors in the inner bore and a pair of annulus sensors in the annulus. A processor sets a gas influx alarm limit based on a steady-state value of an acoustic parameter measured by the pair of inner bore sensors in an absence of a gas influx and a steady-state value of the acoustic parameter measured by the annulus sensors in the absence of the gas influx. The processor determines a gas influx in the wellbore when a subsequent value of the acoustic parameter is outside of the alarm limit and performs an action at the work string to counteract the gas influx in the wellbore.

Abstract: A downhole probe assembly is employed in a wellbore to mitigate the effects of hoop stress on the operation of the probe assembly. A shaped head is driven radially into the geologic formation surrounding the wellbore. A sensor and/or fluid ports may thereby be delivered to a radial depth in the geologic formation beyond a hoop stress regime associated with the wellbore. In this manner, analysis and fluid communication with the geologic formation may not be hindered by the hoop stress regime surrounding the wellbore. The probe assembly may be employed in microfracture tests in which fluid is injected into geologic formation through mechanical fractures created by the shaped heads extending through the hoop stress regime. The fluid injected through the hoop stress regime may more readily interact with the geologic formation, and subsequent analysis of the injected fluids may yield more relevant information about the geologic formation.

Abstract: The present disclosure describes a downhole tool including an electrically operated radiation generator that selectively output radiation to a surrounding environment based at least in part on supply of electrical power; and a control system that determines likelihood of exposing living beings in the surrounding environment to output radiation by determining whether one or more check conditions is met; determine that each of the one or more check conditions is met before instructing the electrically operated radiation generator to output radiation; and instruct the electrically operated radiation generator to cease output of radiation when at least one of the one or more check conditions is no longer met.

Abstract: A polymer is flowed through a slim tube including porous media until steady state is achieved. A temperature of the porous media with the polymer is adjusted to emulate a reservoir temperature. A slug of a gel solution is flowed through the porous media in the slim tube. The gel solution includes the polymer and a crosslinker. The gel solution is configured to at least partially solidify at the temperature. Multiple pressure drops across the porous media in the slim tube are measured at corresponding locations along a length of the slim tube while the slug flows through the porous media in the slim tube. The slug at least partially solidifies within the slim tube, causing an increase in pressure. A location of gelation of the slug of gel solution within the slim tube is determined based on the increase in pressure.

Abstract: A drilling fluid system and associated method for supplying drilling mud to a drilling operation includes a plurality of first sensors associated with a first mud pit, configured to measure a plurality of properties of the drilling mud in the first mud pit, a plurality of second sensors associated with a second mud pit, configured to measure the plurality of properties of the drilling mud in the second mud pit, and a control unit configured to receive measurements from the plurality of first sensors and the plurality of second sensors, determine which of the mud pits comprises drilling mud with a desired plurality of properties, and cause to operate a first valve associated with the first mud pit or a second valve associated with the second mud pit for selecting drilling mud from the first mud pit or the second mud pit based on the determination.

Abstract: A fracture model for a hydraulic fracture in a wellbore can be updated and calibrated. Information about a microseismic event can be received from a sensor that is monitoring a subterranean formation. The information can be received subsequent to a fracking fluid being introduced into the formation. An observed geometry of a hydraulic fracture can be determined based on the information and a predicted geometry of the fracture can be determined based on properties of the fracking fluid and a fracture model. The fracture model can be updated using the information about the microseismic event where it is determined that an uncertainty value of the observed geometry does not exceed a pre-set maximum. The uncertainty value can be based on the predicted geometry of the hydraulic fracture.

Abstract: Transducer assemblies may include a sensor and a housing including a pass-through portion comprising at least one aperture in a portion of the housing extending along a longitudinal axis of the housing and the sensor. Methods of forming transducer assemblies may include welding a first housing section of the transducer assembly to a second housing portion of the transducer assembly and forming at least one aperture in the first housing section extending along a longitudinal axis of the transducer assembly, along a chamber for holding a sensor, and through the weld.

Abstract: A flow rate verification unit that uses the pressure variation value per unit time of a pressure measurement value measured by a pressure gauge and a temperature measurement value measured by a thermometer in a state where a second shut-off valve is closed to calculate the volume between a flow-rate control valve and the second shut-off valve and verifies the flow rates of mass flow controllers one at a time, wherein a first verification side connection part attachably and detachably connected to an integrated gas unit is provided upstream from the pressure gauge and a serially connected verification gas input valve, verification side mass flow controller, and verification side flow rate control valve are provided in parallel with the second shut-off valve.

Abstract: A method and apparatus for automatically testing high pressure and high temperature sedimentation of slurries is described. The method includes pumping a sample drilling fluid into a test cell. The sample drilling fluid may be subjected to a pre-determined pressure and a pre-determined temperature for a pre-determined period of time. The test cell may also be oriented at non-vertical angle. The sample drilling fluid may be pumped out of the test cell and the density of the sample drilling fluid automatically measured relative to a displaced fluid volume of the sample drilling fluid.

Abstract: A formation tester places an isolation device, preferably a probe, in fluid communication with a formation to determine formation pressures. The tester's controller uses a pressure pre-test process to autonomously control operation. The controller measures drawdown pressure and interval as the tester draws down pressure in flowline coupled to the probe. If the drawdown pressure indicates a dry test has occurred, the process is aborted. Otherwise, the controller measures buildup pressure and interval by allowing buildup of pressure of the flowline. The controller permits this to continue until the interval is longer than the drawdown interval and/or until a rate of the buildup falls below a predetermined rate. If the buildup pressure is too tight relative to the drawdown pressure, the controller aborts the test. Eventually, the controller measures a final buildup pressure when the buildup terminates. A new drawdown rate and volume can be determined for subsequent formation tests.

Abstract: A method of measuring a formation parameter in the process of drilling a well penetrating the rock formation is disclosed. A section of the well is provided with a drill string comprising a drilling bit at its distal end; a first fluid is circulated through the drilling bit and invades the rock formation; a formation evaluation tool mounted onto the drill string is used to measure the formation parameter; the formation parameter is used to select the time at which a second fluid is circulated through the drilling bit; such that the second fluid alters the response of the rock formation to the formation evaluation tool; the second fluid is circulated through the drilling bit to start invading the formation; and the formation evaluation tool is used to repeat the measure of the formation parameter while circulating the second fluid.

Abstract: A technique facilitates measuring loads while compensating for the effects of differential pressure. The technique utilizes a load cell comprising a chassis and a sensing element mounted on the chassis. A housing encloses the sensing element in a chamber formed between the chassis and the housing. The housing is connected to the chassis in a manner to transfer loading, e.g. compressive, tensile, and/or torque loading. A pressure compensating piston is positioned within an interior of the chassis and the housing. A plurality of seal points is located in a manner which isolates the sensing element from the effects of differential pressures between the interior and an exterior of the load cell.

Abstract: A system and a method may determine formation strength of a well. The system and the method may use pressure measurements and temperature measurements to determine controlled fracture pressures before the uncontrolled fracture pressure is reached. The system and the method may use pressure measurements and temperature measurements to determine closure stresses while drilling and may use the closure stresses with core and log measurements to optimize a hydraulic stimulation program.

Abstract: A transmitter housing for a drilling device having a drilling fluid feed line comprises a collector space formed in the interior of the transmitter housing for accommodating a pressure sensor of a locating probe.

Abstract: A pressure measurement system for use with a subterranean well can include a chamber positioned in the well, the chamber having an upper portion and a lower portion as positioned in the well, and a device which, in response to gravity acting on the device, selects the upper portion of the chamber for communication with a line extending to a remote location. A method of measuring pressure in a well can include introducing a chamber into the well, then selecting a vertically upper portion of the chamber, and establishing communication between the upper portion of the chamber and a line extending to a remote location.

Abstract: A downhole tool includes a downlinking system deployed in a downhole tool body having an internal through bore. The downlinking system includes a differential pressure transducer configured to measured a pressure difference between drilling fluid in the internal through bore and drilling fluid external to the tool (in the borehole annulus). The differential transducer is electrically connected with an electronic controller (deployed substantially anywhere in the drill string) that is configured to receive and decode pressure waveforms.

Abstract: An apparatus and method for producing pressure signals which indicate when weight-on-bit, during the drilling of a wellbore, exceed a predetermined, upper limit. The apparatus includes a first mandrel and a second mandrel that inserts into and is axially moveable within the first mandrel. The position of the second mandrel may be dependent upon the balance of a biasing member's biasing strength and the weight-on-bit exerted on the drill bit. If weight-on-bit values overcome the biasing strength of the biasing member, the second mandrel may move uphole within the first mandrel and create a pressure signal that is detectable at surface so that the operator is made aware that weight-on-bit values exceed the upper limit.

Abstract: A pressure measurement system for use with a subterranean well can include a chamber positioned in the well, the chamber having an upper portion and a lower portion as positioned in the well, and a device which, in response to gravity acting on the device, selects the upper portion of the chamber for communication with a line extending to a remote location. A method of measuring pressure in a well can include introducing a chamber into the well, then selecting a vertically upper portion of the chamber, and establishing communication between the upper portion of the chamber and a line extending to a remote location.

Abstract: A production monitoring system (10) comprises a plurality of injection and production units (80) coupled in operation to sensors (410) for measuring physical processes occurring in operation in the injection and production units (80) and generating corresponding measurement signals (420) for computing hardware (400). The computing hardware (400) is operable to execute software products (300) for processing the signals (420). Moreover, the software products (300) are adapted for the computing hardware (400) to analyze the measurement signals (420) to abstract a parameter representation of the measurement signals (420), and to apply a temporal analysis of the parameters to identify temporally slow processes and temporally fast processes therein, and to employ information representative of the slow processes and fast processes to control a management process for controlling operation of the system (10).

Abstract: The present invention relates to a method for determining a variation of a flushing medium flow at a rock drilling apparatus, where a compressor (8;301) discharges a flow of pressurized gas, where said gas flow at least partially is used as flushing medium during drilling with a tool (3), wherein, during drilling, said flushing medium is led to said tool (3) for flushing away drilling remnants. The method includes to determine a rate of a pressure variation of said flushing medium, and generating a signal when said determined rate exceeds a first value. The invention also relates to a system and a rock drilling apparatus.

Abstract: A system and method for determining at least one fluid characteristic of a downhole fluid sample using a downhole tool are provided. In one example, the method includes performing a calibration process that correlates optical and density sensor measurements of a fluid sample in a downhole tool at a plurality of pressures. The calibration process is performed while the fluid sample is not being agitated. At least one unknown value of a density calculation is determined based on the correlated optical sensor measurements and density sensor measurements. A second optical sensor measurement of the fluid sample is obtained while the fluid sample is being agitated. A density of the fluid sample is calculated based on the second optical sensor measurement and the at least one unknown value.

Abstract: A downhole tool includes a downlinking system deployed in a downhole tool body having an internal through bore. The downlinking system includes a differential pressure transducer configured to measured a pressure difference between drilling fluid in the internal through bore and drilling fluid external to the tool (in the borehole annulus). The differential transducer is electrically connected with an electronic controller (deployed substantially anywhere in the drill string) that is configured to receive and decode pressure waveforms.

Abstract: Apparatus and methods for estimating a downhole property are provided. The apparatus may include a downhole tool having a predetermined temperature calibration based at least in part on an expected downhole temperature and a temperature controller in communication with the downhole tool that maintains a downhole tool temperature substantially within the predetermined temperature calibration. A method may include conveying a downhole tool having a predetermined temperature calibration based at least in part on an expected downhole temperature in a well borehole and adjusting the temperature of the downhole tool during downhole operation to maintain a downhole tool temperature substantially within the predetermined temperature calibration.

Abstract: The invention relates to fluid sampling in a test that is used to determine physical and chemical characteristics of the fluids in a subterranean reservoir. The method reconstructs the entire pressure history of the fluid parcel that is captured in the fluid samplers during a test. Using this reconstructed pressure history of the samples, the quality of the samples, particularly, whether there is a phase change in the samples during the test, can be accurately quantified.

Abstract: This application relates to various methods and apparatus for rapidly obtaining accurate formation property data from a drilled earthen borehole. Quickly obtaining accurate formation property data, including formation fluid pressure, is vital to beneficially describing the various formations being intersected. For example, methods are disclosed for collecting numerous property values with a minimum of downhole tools, correcting and calibrating downhole measurements and sensors, and developing complete formation predictors and models by acquiring a diverse set of direct formation measurements, such as formation fluid pressure and temperature. Also disclosed are various methods of using of accurately and quickly obtained formation property data.

Abstract: A method to detect leaks in a rotating control device includes positioning a leak detection device in communication with a chamber located between an upper sealing element and a lower sealing element of the rotating control device, and signaling with the leak detection device when a pressure of the chamber exceeds a selected critical pressure.

Abstract: A system for testing a drilling fluid including a vessel having a fluid inlet, a filtrate outlet, a fluid outlet, and at least one permeable media disposed within the vessel. The system further including a base fluid container in fluid communication with the fluid inlet, a test fluid container in fluid communication with the fluid inlet, a filtrate container in fluid communication with the filtrate outlet, and a collection container in fluid communication with the fluid outlet. Additionally, the system includes a data acquisition device configured to receive data from at least one of the vessel, the fluid container, the filtrate container, and the collection container. Also, a method for determining sealing characteristics of a drilling fluid including injecting a test fluid having a fluid loss control material from at least fluid container to a vessel, the vessel having a permeable media having two plates disposed to create a variable gap.

Abstract: An apparatus to detect a pressure signal in a fluid flowing in a conduit comprises a flexible band sized to fit at least partially around the conduit. An optical fiber is flexibly adhered to the flexible band. At least one fastener is attached to the flexible band to fasten the flexible band at least partially around the conduit. A method for detecting a pressure signal in a conduit comprises adhering an optical fiber to a flexible band. At least one fastener is attached to the band. The band is fastened around the conduit such that a strain induced in the conduit by the pressure signal is transmitted to the optical fiber.

Abstract: A rotating control drilling device includes an upper sealing element and a lower sealing element positioned around a drillstring and forming a chamber therebetween and a leak detection device. The leak detection device includes a piston in communication with the chamber, a magnet disc disposed on an end of the piston, and a plurality of magnetic sensors arranged in a magnetic sensing ring around the rotating control drilling device. Upon reaching a selected critical pressure in the chamber, a spring is configured to compress as the magnet disc is positioned proximate to the plurality of magnetic sensors. Furthermore, a method to detect leaks in a rotating control device includes positioning a leak detection device in communication with a chamber located between upper and lower sealing elements and signaling with the leak detection device when a pressure of the chamber exceeds a selected critical pressure.

Abstract: Device (1) for formation testing while drilling, comprising a drill string (2) with a packer (3) arranged on the drill-string above a drilling-bit (7), the packer can be expanded and thereby isolate a lower open part (6) of a well-bore, distinguished in that the packer is fastened sealingly but slideably on a distance (4) of the well-bore, such that the drill-string can be brought up and down, with or without rotation, within said distance while the packer stands stationary expanded in the well-bore, and the device comprises at least one pressure transmitter for measuring and transferring in real-time to the surface measured pressure in the isolated lower open part of the well-bore. Methods for formation testing utilizing the device. Device for formation testing of a production well.

Abstract: Disclosed herein is a method of detecting a downhole washout. The method includes, positioning a plurality of sensors along a downhole drillstring, communicatively coupling the plurality of sensors to a processor, and analyzing data sensed by the plurality of sensors with the processor for relationships indicative of a washout.

Abstract: A device for and method of testing fluid compatibility may include placing a first fluid in a fixed-volume testing chamber and placing a second fluid in a sample chamber. The method may also include heating the fixed-volume testing chamber to about a temperature of a subterranean environment and pressurizing the fixed-volume testing chamber to about a pressure of the subterranean environment. The method may further include determining, at a temperature and pressure of about the temperature and pressure of the subterranean environment, a first rheology value of the fluid within the fixed-volume testing chamber, moving a portion of the second fluid from sample chamber into the fixed-volume testing chamber, and determining, at a temperature and pressure of about the temperature and pressure of the subterranean environment, a second rheology value of the fluid within the fixed-volume testing chamber.

Abstract: A device to measure a fluid pressure comprises a pressure sensing element 10 and a pressure readout element 20. The pressure sensing element 10 comprises a cavity 11 capped by a flexible membrane 13, the cavity having a length d that varies with the fluid pressure P1 applied on the flexible membrane 13. The pressure readout element 20 comprises a light source 24 for providing an incident beam of a determined wavelength range directed towards the cavity and an optical spectral analyzer 25 for measuring a power spectrum of a return beam reflected by the cavity, and processing means 27 for determining the cavity length d and the fluid pressure P1 based on the power spectrum.

Abstract: A rotating control drilling device includes an upper sealing element and a lower sealing element positioned around a drillstring and forming a chamber therebetween and a leak detection device. The leak detection device includes a piston in communication with the chamber, a magnet disc disposed on an end of the piston, and a plurality of magnetic sensors arranged in a magnetic sensing ring around the rotating control drilling device. Upon reaching a selected critical pressure in the chamber, a spring is configured to compress as the magnet disc is positioned proximate to the plurality of magnetic sensors. Furthermore, a method to detect leaks in a rotating control device includes positioning a leak detection device in communication with a chamber located between upper and lower sealing elements and signaling with the leak detection device when a pressure of the chamber exceeds a selected critical pressure.

Abstract: This application relates to various methods and apparatus for rapidly obtaining accurate formation property data from a drilled earthen borehole. Quickly obtaining accurate formation property data, including formation fluid pressure, is vital to beneficially describing the various formations being intersected. For example, methods are disclosed for collecting numerous property values with a minimum of downhole tools, correcting and calibrating downhole measurements and sensors, and developing complete formation predictors and models by acquiring a diverse set of direct formation measurements, such as formation fluid pressure and temperature. Also disclosed are various methods of using of accurately and quickly obtained formation property data.

Abstract: A method for identifying annular gas sources in a wellbore is disclosed. In one embodiment, the method comprises providing a set of parameters, wherein the set of parameters corresponds to depths in the wellbore. In addition, the method comprises analyzing annular gas in the wellbore to provide isotopic data of the annular gas. The method further comprises correlating the isotopic data to the set of parameters to identify the annular gas source.

Abstract: An apparatus and method for use in determining pressure at a formation of interest in-situ. A carrier carrying a tool is conveyed in a borehole. The tool includes a sealing member and a port exposable to the formation of interest. A formation fluid sampling chamber is separated from a hydraulic fluid chamber by a flexible member that allows pressure communication from the fluid sampling chamber to the hydraulic fluid chamber. A sensor senses pressure in the hydraulic fluid for determining pressure in the sampling chamber.

Abstract: A method and computer program product of either preventing or minimizing pore pressure increase near the wellbore wall within argillaceous formations through which a borehole has been drilled. By interpreting relevant drilling experience data, the type, extent and time-dependency of wellbore instability mechanisms are determined. The impact of drilling mud designs on the time-dependent wellbore instability and hole enlargement is determined by back-analyzing observed drilling events. At least one field-based criterion relationship between net mud weight reduction percentage ratio and hole enlargement is determined. A maximum allowable percentage ratio(s) of net mud weight reduction and either breakout mud weight or mud weight used for the adopted maximum hole enlargement that the wellbore may experience during drilling is determined. Drilling mud salinity value and salt type to satisfy maximum allowable percentage ratio(s) is then determined.

Abstract: An apparatus including a drill collar having an outer surface, an assembly for interaction with an earth formation coupled to the drill collar, the assembly including a first member to extend beyond the drill collar outer surface and a second member to extend beyond the first member and toward the earth formation to receive formation fluids. An apparatus including an MWD tool having an outer surface, a formation testing assembly coupled to the MWD tool, the formation testing assembly recessed beneath the outer surface in a first position and including a piston to extend beyond the outer surface to a second position and an inner sampling member to extend beyond the piston to a third position.

Abstract: A method for simulating water-hammer waves in a borehole is used to estimate formation parameters such as porosity and permeability, and to design completion strings. The simulation method uses a model that has a plurality of layers, at least one of the layers includes radial layering. Determined formation properties from analysis of the waterhammer are used in development operations.

Abstract: A method of estimating a formation pressure in a wellbore is provided that in one aspect includes measuring a hydrostatic pressure at a selected location in the wellbore, and estimating supercharge pressure as a function of time using a forward model that utilizes the hydrostatic pressure and at least one property of mud in the wellbore that is a function of time. In another aspect, the method may estimate an initial formation pressure at a selected location in a wellbore by obtaining a hydrostatic pressure and at least three formation pressure measurements at three separate times at the selected location, and estimating the initial formation pressure using the hydrostatic pressure, the three pressure measurements and an internal mudcake parameter.

Abstract: This application relates to various methods and apparatus for rapidly obtaining accurate formation property data from a drilled earthen borehole. Once obtained, the formation property data, including formation fluid pressure, may be corrected, calibrated and supplemented using various other data and techniques disclosed herein. Furthermore, the formation property data may be used for numerous other purposes. For example, the data may be used to correct or supplement other information gathered from the borehole; it may be used to supplement formation images or models; or, it may be used to adjust a drilling or producing parameter. Various other uses of accurately and quickly obtained formation property data are also disclosed.

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 while drilling system and method for determining downhole parameters is provided. The system includes a retrievable while drilling tool positionable in a downhole drilling tool, a sensor chassis and at least one sensor. The while drilling tool is positionable in the downhole drilling tool and has a first communication coupler at an end thereof. The sensor chassis is supported in the drilling tool. The sensor chassis has a second communication coupler at an end thereof for operative connection with the first communication coupler. The sensor is positioned in the chassis and is adapted to measure internal and/or external parameters of the drilling tool. The sensor is operatively connected to the while drilling tool via the communication coupler for communication therebetween. The sensor may be positioned in the while drilling tool and retrievable with the drilling tool. Preferably, the system is operable in high temperature and high pressure conditions.

Abstract: A method for determining formation pressure at a depth region of formations surrounding a borehole, including: keeping track of the time since cessation of drilling at the depth region; deriving formation permeability at the depth region; causing wellbore pressure to vary periodically in time and determining, at the depth region, the periodic and non-periodic component of pressure measured in the formations; determining, using the time, the periodic component and the permeability, the formation pressure diffusivity and transmissibility and an estimate of the size of the pressure build-up zone around the wellbore at the depth region; determining, using the time, the formation pressure diffusivity and transmissibility, and the non-periodic component, the leak-off rate of the mudcake at the depth region; determining, using the leak-off rate, the pressure gradient at the depth region; and extrapolating, using the pressure gradient and the size of the build-up zone, to determine the formation pressure.

Abstract: Methods for estimating formation pressure from data taken during the drawdown cycle are presented. In one aspect, a method of determining a formation pressure during drawdown of a formation comprises sampling fluid from a formation using a downhole tool having a sample volume and a fluid sampling device. At least one time dependent parameter of interest related to the fluid is determined during the drawdown. The at least one time dependent parameter is analyzed using a plurality of calculation techniques to determine the formation pressure. The techniques include (i) a first pressure derivative technique; (ii) a second pressure derivative technique; (iii) a formation rate analysis technique; (iv) a dp/dt-ratio technique; and (v) a stepwise drawdown technique.

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: A method for addressing the problem known as formation breathing occurring during the drilling of a subsea well in an earth formation in performing a series of leak off tests to determine the earth formation fracture propagation pressure and the earth formation fracture reopen pressure and maintaining the hydrostatic pressure on the earth formation in a range between the fracture reopen pressure and the fracture propagation pressure.