Abstract: A method for detecting pressure disturbances in a formation accessible by a borehole while performing an operation includes positioning a tool within the borehole, positioning a first probe of the tool at a first location, positioning a second probe of the tool at a second location remote from the first location to obtain a pressure reading, performing an operation with the first probe, detecting the presence of a first phase fluid within the tool, detecting a pressure disturbance within the formation with the second probe, and identifying a second phase fluid based on the detection of the pressure disturbance. Other methods and systems for detecting pressure disturbances in the formation are further shown and described.

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: Techniques for evaluating physical aspects of a formation fluid from within a wellbore include changing at least one of a pressure on and a temperature of a sample of the formation fluid and transmitting at least one acoustic pulse through the fluid sample and analyzing acoustic information collected. Apparatus and methods for the evaluating involve using at least one acoustic transducer. Analyzing typically involves use of formulae that relate equation (s) of state and other properties for the fluid to a change in the sound speed in the fluid.

Abstract: A sampling tool for retrieving one or more samples from a wellbore drilled in a subterranean formation includes a coring device retrieving a core from a wellbore wall, wellbore isolation devices that isolate an annular region proximate to the coring device; and a flow device that flows fluid out of the isolated region. During operation, the sampling tool is positioned adjacent a formation of interest. The isolation device is activated to isolate an annular region proximate to the sampling tool. Decentralizing arms can be used to position the coring device next to the wellbore wall. Thereafter, the flow device flows fluid out of the isolated annular region. When the isolated region includes mostly formation fluid, the coring device is activated to retrieve a core from a wall of the wellbore in the isolated annular region and store it in formation fluid.

Abstract: The present invention provides an objective bubble point pressure determination method enables new applications of downhole PV (Pressure Volume) test results such as in situ measurement of the bubble point pressure for use as a quality control parameter for sampling. The present invention provides a method and apparatus to fit data points to a curve and to smooth these points over an interval of N points. The derivative of the curve is determined to obtain peak acceleration. The peak acceleration represents the bubble point pressure. This bubble point pressure is verified by comparison to changes in fluid compressibility and visual observation of a pressure volume plot history.

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: 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: A method and apparatus for formation testing is disclosed. In a preferred embodiment, a formation testing tool includes a longitudinal body with a flowbore; a plurality of extendable centralizing pistons coupled to the body; an extendable sample device coupled to the body; and a centralizing hydraulic circuit configured to cause each of the plurality of centralizing pistons to extend at substantially the same rate. The centralizing hydraulic circuit includes a series of flow control and pressure-determining valves configured to extend the centralizing pistons at substantially the same rate, and to help maintain stability in the hydraulic circuit in response to external pressures. In some embodiments, the extendable sample device is preferably configured to be recessed beneath a surface of the body in a first position and to extend beyond the surface in a second position.

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: 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: The present invention provides a down hole spectrometer for determination of dew point pressure to determine an associated optimal pumping rate during sampling to avoid precipitation of asphaltenes in a formation sample. A sample is captured at formation pressure in a controlled volume. The pressure in the controlled volume is reduced. Initially the formation fluid sample appears dark and allows less light energy to pass through a sample under test. The sample under test, however, becomes lighter and allows more light energy to pass through the sample as the pressure is reduced and the formation fluid sample becomes thinner or less dense under the reduced pressure. At the dew point pressure, however, the sample begins to darken and allows less light energy to pass through it as apshaltenes begin to precipitate out of the sample. Thus, the dew point is that pressure at which peak light energy passes through the sample.

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: Determining the in situ effective mobility of a formation layer comprises selecting a location in the formation layer; lowering in the borehole traversing the formation layer a tool that comprises a central conduit having an inlet and being provided with a pressure sensor, a fluid receptacle having an inlet opening into the central conduit. a fluid analyser, and means for discharging fluid; making an exclusive fluid communication between the formation and the inlet of the central conduit; allowing formation fluid to pass through the central conduit, analysing the fluid, allowing the formation fluid to enter into the fluid receptacle when the fluid is the substantially uncontaminated formation fluid, and measuring the pressure build-up: and determining the effective mobility from the pressure build-up.

Abstract: The pressure reading tool includes a housing with an interior chamber and an orifice extending from the chamber to the exterior of the housing. A pulse member with a magnetostrictive ring and an excitation source are disposed within the chamber to produce a highly agitated fluid discharge through the orifice. The magnetostrictive ring, chamber volume, and orifice cooperate to induce Helmholtz resonance frequencies in the fluid in the chamber to thereby enhance the agitation of the fluid discharge. A sheathing encapsulates the pulse member to protect it from contact with the fluid. A dampening element is also interposed between the pulse member and housing to isolate vibration.

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 method for detecting a leak in a drill string valve used when drilling a subsea well. The method comprises measuring a first inlet pressure at a subsea mudlift pump while a subsea mudlift pump and a surface pump are operating and before a well is fully shut-in and measuring a second inlet pressure at the subsea mudlift pump after the mudlift pump and the surface pump are shut down and after the well is fully shut-in. The first and second subsea mudlift pump inlet pressure measurements are then compared, and a check is performed to determine if the subsea mudlift pump inlet pressure has increased by an amount greater than an estimated annular friction pressure.

Abstract: The compressibility of a formation hydrocarbon sample is determined downhole by using a borehole tool to obtain the sample downhole, and, at two different pressures, subjecting the sample to near infrared illumination and conducting spectral absorption measurement of peaks at and/or around about 6,000 cm−1 and/or at and/or about 5,800 cm−1 (the absorption peaks of methane and crude oil respectively). The compressibility of the sample is determined from the change in the peak areas, the change in pressure, and the measured peak area itself. According to a preferred embodiment of the invention, the pressure is changed at least 2000 pounds per square inch (psi), and preferably 4000 or more psi between measurements.

Abstract: A non-invasive method and apparatus for monitoring changes in intracranial pressure which removes extracranial effects from the measurements. The method and apparatus can include the supplying of a fixed frequency electrical output to a transducer coupled to the patient's head, thereby generating an acoustical tone burst in the patient's head which generates a first echo and a second echo, the first echo reflecting from a first interface in the side of the patient's head coupled to the transducer, and the second echo reflecting from a second interface at the opposite side of the patient's head. The first and second echoes are received by the transducer which can generate a first electrical signal and a second electrical signal, wherein the first and second electrical signals vary in accordance with the corresponding first and second echoes.

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: The present invention provides a method for improving the quality of a formation fluid sample by taking the sample at a time when the formation fluid composition contains the most favorable portion of hydrocarbons. This task is accomplished by determining in real-time, the composition of the fluid flowing into a downhole tool from the formation. This method determines the optical density of the fluid as the fluid flows through the tool. An optical spectrum is generated from the density measurement. The optical spectrum is compared to a composite spectrum generated from a database of known fluid samples. As a result of the comparisons, there is a determination of the derivations between corresponding features of the two spectra. Adjustments are made to the components of the composite spectrum until the deviations between the two spectra are at an acceptable minimum. Determinations of the fluid composition are made from the composition of the composite spectrum at the minimum deviation.