Abstract: A technique that usable in a subterranean well includes deploying a first sensor in a remote location to measure a distribution of a characteristic along a segment at the location. The technique includes deploying a second sensor downhole to measure the characteristic at discrete points within the segment. The second sensor is separate from the first sensor.

Abstract: A method for determining the composition of a fluid by using measured properties of the fluid. One embodiment of the method of the current invention generally comprises: selecting a fluid property that has a response to fluid composition that is linear, or can be approximated as linear; measuring the selected fluid property at a series of specific time intervals; and plotting the measured property as a function of the selected property. In effect, plotting the measured property as a function of fluid composition in an arbitrary set of units. This allows for a in-situ qualitative evaluation of fluid composition by measuring a fluid property that has a known linear relationship to fluid composition. Another embodiment of the present invention further comprises, establishing the endpoints of contamination and plotting the measured properties through these endpoints. Once the endpoints have been established a quantitative evaluation of the fluid composition can be performed.

Abstract: Method, apparatus and systems for drilling wells, such as for production of petroleum products and ensuring efficient well drilling and protection of well drilling systems during drilling operations. A closed-loop drilling control system, including a digital switching control regulator (SCR) module is provided for automated actuation of selected drilling rig controls responsive to downhole and surface measurements of drilling parameters. The closed-loop drilling control system is responsive to digital data from a measuring-while-drilling (MWD) tool for refining the drilling controls by automated correction of driller inputs to the drilling controls of the well drilling system during drilling operations. The downhole data, such as surface weight on bit, downhole weight on bit, pressure and flow rate of downhole drilling fluid hydraulics, etc.

Abstract: The invention is a method for direct updating, by dynamic production data, of a fine geologic model representative of the distribution, in a reservoir, of a physical quantity characteristic of the subsoil structure. The method couples inversion and upscaling techniques allowing optimization of petrophysical parameters of a rougher simulation model resulting from the fine geologic model. Direct parameterization of the fine geologic model is performed followed by upscaling only as a means of obtaining rapidly an approximation of simulation results and of derivatives thereof in relation to the parameterization of the fine geologic model. The model has applications for determination of a development scheme such as optimizing the production of a hydrocarbon reservoir.

Abstract: A new averaged/continuum model is presented for simulation of wormhole formation during matrix stimulation of carbonates.

Abstract: A measurement apparatus for making magnetic and gravity component measurements in a borehole, including measurements made while the apparatus is rotating about the borehole axis, comprising a magnetic field component sensing device having at least two axes of sensitivity normal to the borehole axis and normal to each other, a gravity field component sensing device having at least two axes of sensitivity normal to the borehole axis and normal to each other, an inertial angular rotation sensing device having an axis of sensitivity along the borehole axis to sense inertial angular motion about the borehole axis, control, power and processing circuitry to operate said sensing devices and to process the outputs of said sensing devices to obtain stabilized component data in a coordinate system that does not rotate with the said measurement apparatus, communication circuitry to transmit output data to auxiliary equipment at the surface or in the borehole, and support structure to support the sensing devices.

Abstract: An automated method is for making a topographical model of an area including terrain and buildings thereon based upon randomly spaced data of elevation versus position. The method may include processing the randomly spaced data to generate gridded data of elevation versus position conforming to a predetermined position grid, processing the gridded data to distinguish building data from terrain data, and performing polygon extraction for the building data to make the topographical model of the area including terrain and buildings thereon.

Abstract: A well-log display (160) having a principle axis (135) matched to a deviation of a section of a well-bore (450) is disclosed. By presenting a well-log (160) at about the same angle as the section of the well-bore under consideration, a person viewing the well-log (160) will have the advantage of easily visualizing the inclination of the well-bore (450) to aid in geo-steering, proper interpretation of well-bore measurements, etc. Such a well-log (160) may be presented as a hardcopy or as an interactive display on a computer screen (642). A presentation (100, 200) of a well-log (160) may include more than just the log itself, for example, a reference diagram (100, 200) of the entire well highlighting (130) or otherwise indicating the part of the well currently being displayed in the well-log.

Abstract: Transverse or tilted magnetic dipole antenna systems are used for electromagnetic logging measurements to determine the anisotropic resistivity of subsurface formations. Combined measurements between transverse or tilted antennas, as well as axial antennas, are used to compensate for receiver antenna mismatch in the system. Some embodiments use model-based parametric inversion to estimate the anisotropic resistivity in the presence of invasion and shoulder-bed effects.

Abstract: A radar-plow drillstring steering system comprises a steering plow and a measurements-while-drilling instrument for mounting just behind the drill bit and downhole motor of a drill rod. The instrument includes a radar system connected to upward-looking and downward-looking horn antennas and a dielectric-constant sensor. The steering plow includes four pressure pads radially distributed around the outside surface and their associated servo motors. A coordinated control of the pressure pads allows the steering plow to push the drillstring and drill bit up-down-left-right. The antennas and sensor are embedded in respective ones of the pressure pads and are used to electronically and non-invasively probe a coal seam to locate its upper and lower boundary layers. The dielectric-constant sensor provides corrective data for the up and down distance measurements. Such measurements and data are radio communicated to the surface for tomographic processing and user display.

Abstract: A borehole survey method is provided for processing continuous measurements of the earth's magnetic and gravitational fields obtained while drilling a borehole. The present invention improves borehole acquisition of targeted geological structures by substantially reducing continuous measurement errors attributable to noise, shock and vibrations from turning the drill bit against rock.

Abstract: A tool generates signals indicative of shear wave slowness of the formation surrounding a borehole. The tool comprises a collar portion adapted for mounting in a drill string, a quadrupole sonic transmitter mounted to the collar portion, and a quadrupole sonic receiver array mounted to the collar spaced apart from the transmitter. A method determines shear wave slowness of the formation. The method includes propagating quadrupole wave energy into the formation and detecting quadrupole dispersive waveforms received at a second location.

Abstract: A portable locator and method are described for tracking the position of a boring tool and/or one or more buried lines within a region. In tracking a boring tool, a flux plane may be used to establish a flux vector as at least an intermediate step in guiding an operator of the portable locator to one or both locate points seen in the boring tool dipole locating field. The horizontal flux vector is used in determining a predicted locate point position. Locating of a locate line in the dipole locating field is performed by determining a predicted locate line angular orientation that is based upon horizontal flux vector determinations. The predicted locate line angular orientation, at least to an approximation, limits the possible directions to and orientations of a predicted locate line relative to the particular orientation of the portable locator at the above ground point.

Abstract: Methods for downhole waveform tracking and sonic labeling employ “tracking algorithms” and Bayesian analysis to classify STC waveforms. More particularly, according to the tracking part of the invention, a probability model is built to distinguish true “arrivals” (e.g. compressional, shear, etc.) from “false alarms” (e.g. noise) before the arrivals are classified. The probability model maps the “continuity” of tracks (slowness/time over depth) and is used to determine whether sequences of measurements are sufficiently “continuous” to be classified as tracks. The probability model is used to evaluate the likelihood of the data in various possible classifications (hypotheses). Prior and posterior probabilities are constructed for each track using the tracking algorithm. The posterior probabilities are computed sequentially and recursively, updating the probabilities after each measurement frame at depth k is acquired.

Abstract: A method for aligning measurements of a hostile environment includes synchronizing at least two clocks, wherein at least a first clock is in the hostile environment, measuring characteristics of the hostile environment, aligning time domain curves of the collected measurements, correlating the curves using one or more events recorded by each clock, and correcting the curves by adding one or more time offsets. The offsets may be added to a found resent event or at other locations on the time domain curve. A second clock may be located outside the hostile environment or within a same or similar hostile environment. The collecting the measurements may be taken by a first measurement tool in a first device near the first clock and in at least a second device coupled to a second clock.

Abstract: A well logging system is disclosed having an improved speed correction apparatus and method. One embodiment comprises a logging sonde, a wireline cable, a distance sensor, a tension sensor, and a surface computer. The logging sonde moves through a wellbore while making logging measurements of the formation around the wellbore. The sonde includes an accelerometer to measure acceleration of the logging sonde. As the wireline cable is reeled in on the surface, the distance sensor detects the length of wireline cable that is retrieved. The tension sensor measures the tension in the wireline cable. The surface computer receives measurements from the accelerometer, the distance sensor, and the tension sensor, and determines intervals in which the logging tool is stuck. At least in part, this is done by finding “slow” intervals in which the wireline cable is stretching at about the same rate that the wireline cable is being reeled in.

Abstract: The present invention provides method of quantifying sample clean up in real time by providing curve-fitting measurements of optical or physical properties of fluid samples in boreholes. Sample fluid is extracted from the formation surrounding the borehole. As fluid continues to be extracted the composition of the extracted sample changes, altering the values of physical properties of the sample being measured. Measurements are made of optical or physical properties of the sampled fluid, and regression analysis is performed on the acquired measured data points. In one embodiment of the invention, iterative methods enable a user to determine an asymptotic value of a physical property, i.e. absorbance, as well as the percent of the progress that the current sample has obtained toward reaching the asymptotic property value and a projected time to reach the asymptotic property value.

Abstract: A technique of estimating electrical parameters of an earth formation accounts for spatial inhomogeneities and frequency dispersion. The results are achieved using a model which is evaluated to generate predicted values for a plurality of electrical signals measured in a borehole in an earth formation as a function of a first set of model electrical parameters, a second set of model electrical parameters and model spatial coordinates of boundaries between regions of the earth formation. Transformations are applied to the measured electrical signals and the predicted values. The electrical parameters and spatial coordinates are selected to cause approximate agreement between the transformed measurements and the transformed predicted values.

Abstract: A method is provided for selecting a cementing composition for sealing a subterranean zone penetrated by a well bore. The method involves comprising determining a group of effective cementing compositions from a group of cementing compositions given estimated conditions experienced during the life of the well, and estimating the risk parameters for each of the group of effective cementing compositions.

Abstract: A method for determining a radial profile of sonic shear velocity of formations surrounding a fluid-containing borehole, including: suspending a logging device in the borehole; transmitting sonic energy from the logging device to establish flexural waves in the formation; receiving sonic energy from the flexural waves and producing, from the received sonic energy, measurement signals at a number of frequencies; determining, at each frequency, the flexural wave velocity in the formation; deriving sonic compressional and shear velocities of the substantially undisturbed formation; deriving sonic compressional velocity of the borehole fluid; and determining the radial profile of sonic shear velocity from the derived compressional and shear velocities of the substantially undisturbed formation, the derived compressional velocity of the borehole fluid, and the flexural wave velocities.

Abstract: A well-log display (160) having a principle axis (135) matched to a deviation of a section of a well-bore (450) is disclosed. By presenting a well-log (160) at about the same angle as the section of the well-bore under consideration, a person viewing the well-log (160) will have the advantage of easily visualizing the inclination of the well-bore (450) to aid in geo-steering, proper interpretation of well-bore measurements, etc. Such a well-log (160) may be presented as a hardcopy or as an interactive display on a computer screen (642). A presentation (100, 200) of a well-log (160) may include more than just the log itself, for example, a reference diagram (100, 200) of the entire well highlighting (130) or otherwise indicating the part of the well currently being displayed in the well-log.

Abstract: The specification discloses a signal processing technique applicable in acoustic logging devices. The method involves receiving a set of acoustic signals and converting those received signals to their frequency domain representation. Values of the frequency domain representations along constant frequencies are correlated to produce a correlation matrix. Eigenvectors and eigenvalues of the correlation matrix are determined, and the eigenvectors corresponding to signals of interest are removed to create a subspace. Thereafter, a series of test vectors, which test vectors embody a series of estimated slowness values, are applied to the subspace vector. If the test vector maps to or may be represented by the subspace, then the estimated slowness embodied in the test vector maps to noise of the system and is not the correct value for the formation. If, however, the test vector does not map to the subspace, then the slowness embodied in the test vector approximates the actual formation slowness.

Abstract: The present invention provides a graphical method to design and modify the trajectory of a well bore. A well bore trajectory plan is comprised of hold and curve sections. Hold sections are generally described by specifying the attitude of the hold and the length of the hold. Curve sections can be described and represented in a variety of ways. The present invention introduces control points that are formed at the intersection of extensions/projections of the two hold sections contacting a curve section. The hold sections contact the curve section at tangent points. The tangent points for a curve section have the same distance to the control point. In operation, as a control point is moved, the direction and inclination of multiple sections of the well plan are simultaneously modified. These simultaneous modifications enable the user to quickly and intuitively modify a well plan.

Abstract: A seismic communication system suitable to communicate information to an underground device is disclosed. A seismic source (preferably on or near the surface of the earth) generates a timed series of seismic shots. These shots are then detected by one or more seismic receivers underground. Depending on the timing of these seismic shots, and the communication protocol selected, various information may be communicated to the underground target. Such a system is particularly desirable when the underground device includes a perforating gun because the perforating gun may not only be remotely detonated without the drawbacks of previous methods, but the detonation of the perforating gun charges may also be detected, giving an indication whether substantially fewer than all of the explosive charges detonated.

Abstract: A system and method provide for electronic development of a bore plan for use in connection with an underground boring machine. Electronically developing a bore plan involves receiving bore path plan information representative of an intended bore path at the bore site, which may include topographical and utility related information. A pre-established bore plan is generated using the received bore path plan information. Actual bore path information is acquired indicative of an actual bore path produced by the boring machine. A modified bore plan is generated using the actual bore path information and at least some of the bore path plan information. The modified bore plan comprises data representative of a modified bore path that minimizes a deviation in alignment between the actual bore path and the intended bore path. Selected bore plan data can be displayed in both textual and graphical forms.

Abstract: Skin-effect corrections are applied to measurements made by a transverse induction logging tool to give corrected measurements indicative of vertical conductivities of a formation. Data from a conventional induction logging tool are inverted or focused to give an isotropic model of formation resistivity. A forward modeling is used to derive from the isotropic model measurements that would be expected with a transverse induction logging tool. Skin-effect corrections are applied to these expected measurements. The formation anisotropy is determined from the skin-effect corrected transverse induction measurements, the skin-effect corrected expected measurements and from the isotropic model conductivities.

Abstract: A method and apparatus are provided for detecting a received acoustic pulse of a selected azimuthal borehole mode in a liquid-containing borehole in a formation. The method uses a sonde having an axial array of acoustic receiver stations aligned with the borehole, each receiver station having an azimuthal array of at least four piezoelectric receiver elements, the receiver elements uniformly spaced apart around the azimuthal array. An acoustic pulse transmitted within the borehole produces an electrical signal at each receiver element. Azimuthal spatial transform filtering is applied to produce data representing a received acoustic pulse of the selected azimuthal borehole mode. In one embodiment, azimuthal spatial DFT filtering is applied to digital data produced by analog to digital conversion. In another embodiment, cosine transform filtering is applied by an apodized receiver element.

Abstract: The present invention relates to a method of determining the proppant friction generated in a fracture of a subterranean formation during a hydraulic fracturing treatment involving injection stages of pad and of proppant-laden fluids. This method is based on close monitoring of surface pressure to define a “net pressure rate” which defines an increase or decrease of net pressure while the job is being pumped, and then relates it with the pressure changes observed with the onset of proppant stages of varying concentrations.

Abstract: A method and apparatus for surveying a three dimensional sub-surface geological structure having seismic scatterers includes establishing an acquisition system (19) having at least two substantially vertical arrays of sensors (20) disposed within the geological structure. Each array (20) includes multiple directional sensing receivers 30 adapted to receive seismic energy (28, 97) produced from the seismic scatterers (24) in response to at least one seismic disturbance (27). The multiple directional sensing receivers (30) are adapted to provide a measurement of the received seismic energy. A recorder records the measurements of the received seismic energy for producing a complete vector field response of the seismic scatterers to the at least one seismic disturbance. Lastly, a processor processes the complete vector field to generate a three-dimensional image.

Abstract: A method, apparatus, and article of manufacture are provided that use measurement data to create a model of a subsurface area. The method includes creating an initial parameterized model having an initial estimate of model parameter uncertainties; considering measurement data from the subsurface area; updating the model and its associated uncertainty estimate; and repeating the considering and updating steps with additional measurement data. A computer-based apparatus and article of manufacture for implementing the method are also disclosed. The method, apparatus, and article of manufacture are particularly useful in assisting oil companies in making hydrocarbon reservoir data acquisition, drilling and field development decisions.

Abstract: A borehole probe and related method and apparatus that enables information related to the depth of the probe to be determined and utilized by the probe to perform tasks. The probe, comparing its sense of depth and other sensed physical and temporal information to pre-defined procedural and conditional constraints, causes a physical action to be performed, or signals another device, or signals the surface. Generally, the probe uses sensed benchmarks within the borehole that have an associated depth as a depth framework. Within the distances between the benchmarks, the probe uses inertial or other distance measuring devices to measure distance from the benchmarks. With accurate and constant knowledge of its own depth, the probe can perform tasks autonomously and at the correct depth.

Abstract: Apparatus, methods and products for monitoring/controlling a reciprocating well producing hydrocarbons from a wellbore, which determine the surface card from a well operating characteristics, determine the downhole card, and display both at the same scale for position.

Abstract: Fracture design for well completion includes determining a conductivity profile for the given reservoir to be fractured. Materials needed to obtain this conductivity profile are selected based on their ability to meet the conductivity objective and their rank based on economic value. A further step gives the designer a pumping schedule to be performed on the surface after an initial test in the actual well. This can reduce the iterations required to optimize a fracturing treatment and significantly reduce the redesign process at the well site.

Abstract: An apparatus and a method for providing three dimensional seismic images using directional sensing rotation within a geological structure's complete vector field produced by seismic energy emanating from seismic scatterers in the sub-surface of the geological structure, which significantly reduces the need for distribution of seismic energy sources and receivers over the entire surface of the geological structure. The apparatus includes an omni-azimuthal source of seismic energy 22 positioned adjacent a surface of a geological structure 18 for emitting a signal 27 of sufficient energy and bandwidth to produce seismic energy 28 and 97 from the seismic scatterers in the geological structure 18. A plurality of arrays of sensors 20 are also provided. Each array 20 has directional sensing receivers 30 aligned in the geological structure 18 for receiving and measuring the seismic energy 28 and 97 to create a complete vector field.

Abstract: Many reservoirs of interest include heavy oil. In such reservoirs, parti at normal temperatures, many instruments commonly used for formation evaluation may not be able to distinguish between heavy oil and bound water in the formation. Passive or active heating is used to elevate the temperature of the fluids in the formation. At elevated temperatures, distinguishing between heavy oil and bound water is easier. Of particular interest is the increase in the resolvability of the transverse relaxation time T2 of NMR spin echo measurements. Additionally, the dielectric constant and the loss tangents of water and heavy oil show different temperature and frequency dependence.

Abstract: The present invention comprises a data delivery system for delivering oilfield data from an acquisition site to a remote delivery site comprising a central data hub computer that processes a workflow order for controlling delivery of the oilfield data, a data acquisition site computer that transmits oilfield data over a first communications network to the central data hub in near real-time in response to the workflow order and a data server that receives data from the central data hub over a second communications network. The data server communicates with multiple remote delivery site computers for the simultaneous display of oilfield data in near real-time at the multiple delivery site computers in response to the workflow order.

Abstract: A method for creating a frequency domain semblance for use in conjunction with acoustic logging tools is disclosed. Such a frequency domain semblance may be obtained by transforming an acoustic signal received at multiple depths into the frequency domain, combining the received waveforms corresponding to the different depth, and expressing the result in a graph with slowness and frequency axes. This graph shows the frequency-slowness location for the acoustic signal, as well as for other related signals that may inadvertently be generated by the acoustic logging tool. This information may then be used to more clearly measure the slowness of the received acoustic signal. Another aspect of the invention is the treatment of two or more time domain semblances as probability density functions of the slowness for an acoustic signal. This enables the combination of time domain semblances from the same depth in the wellbore.

Abstract: The present invention provides a method for determining magnetometer errors during wellbore survey operations. It is capable of determining errors on up to three axes, with or without the use of an external reference measurement of the local magnetic field, and is capable of providing an accurate result using data from a minimum number of surveys. A model is used to correct the observed data and the corrected data are transformed from the tool coordinate system to a different coordinate system referenced to the earth. The difference between the corrected transformed data and reference data in the earth coordinate system is minimized to determine the model parameters. The present invention also provides a method for determining residual uncertainty in the measurements and for quality control of the measurements.

Abstract: A method provides for locating and measuring mechanical damage in rock surrounding a borehole by detecting one or both of reductions in ultrasonic compressional wave velocity in the rock as a function of azimuth, and by detecting focused acoustic energy in the rock from local increases in ultrasonic compressional wave amplitude resulting from velocity gradients. A first preferred embodiment uses a combination of azimuthal ultrasonic compressional wave velocity data and azimuthal ultrasonic compressional wave energy data. A second embodiment uses azimuthal ultrasonic compressional wave velocity data and omni-directional sonic velocity data, with a comparison test or a curve fitting test. A third embodiment uses azimuthal ultrasonic compressional wave energy data.

Abstract: Techniques are provided to transform attenuation and phase measurements taken in conjunction with a drilling operation into independent electrical parameters such as electrical resistivity and dielectric values. The electrical parameters are correlated with background values such that resulting estimates of the electrical parameters are independent of each other. It is shown an attenuation measurement is sensitive to the resistivity in essentially the same volume of an earth formation as the corresponding phase measurement is sensitive to the dielectric constant. Further, the attenuation measurement is shown to be sensitive to the dielectric constant in essentially the same volume that the corresponding phase measurement is sensitive to the resistivity. Techniques are employed to define systems of simultaneous equations that produce more accurate measurements of the resistivity and/or the dielectric constant within the earth formation than are available from currently practiced techniques.

Abstract: A well logging system is disclosed having an improved speed correction apparatus and method. One embodiment comprises a logging sonde, a wireline cable, a distance sensor, a tension sensor, and a surface computer. The logging sonde moves through a wellbore while making logging measurements of the formation around the wellbore. The sonde includes an accelerometer to measure acceleration of the logging sonde. As the wireline cable is reeled in on the surface, the distance sensor detects the length of wireline cable that is retrieved. The tension sensor measures the tension in the wireline cable. The surface computer receives measurements from the accelerometer, the distance sensor, and the tension sensor, and determines intervals in which the logging tool is stuck. At least in part, this is done by finding “slow” intervals in which the wireline cable is stretching at about the same rate that the wireline cable is being reeled in.

Abstract: A technique for centralized processing of oilfield or waterfield engineering data for design and analysis from distributed locations is disclosed. In one aspect, the invention includes a method comprising: acquiring a plurality of oilfield or waterfield data; establishing a communications link between a client computing device to a server computing device; inputting data from the client computing device to the server computing device; processing the data at the server computing device; and communicating the results to the client computing device. In a second aspect, the invention includes a computing system, comprising: a client computing device; a server computing device interconnected with the client computing device; and an analysis tool resident on the server. The analysis tool includes a calculation engine capable of analyzing the data entered from the client computing device; and a plurality of program utilities for use by the calculation engine in analyzing the data.

Abstract: A method for determining properties of an earth formation surrounding an earth borehole that involves: providing a logging device moveable through the borehole; transmitting sonic energy into the formation; receiving sonic energy that has traveled through the formation; producing signals representative of the received sonic energy; determining whether the formation is anisotropic; determining whether the formation is inhomogeneous; and outputting a characterization of the formation as one of the following types: isotropic/homogeneous, anisotropic/homogeneous, isotropic/inhomogeneous, and anisotropic/inhomogeneous.

Abstract: This is a system to record process data only when it has changed enough to be significant to the process being controlled and monitored. Unlike conventional fixed interval data loggers it does not miss a significant event which occurs between fixed time interval data sets. Neither does it fill its memory with repetitive constant data values. The time for data recording is determined by the process behavior and not known in advance. For this reason the time at which a data set was recorded is included within it. This system has a clock calendar, non-volatile memory, microprocessor control, and data replay and display capability. Data can be replayed on the included display using simple reverse and forward buttons to sequentially scan through data records in the non-volatile memory just as if it were a tape recording. A system can be incorporated into process controls to substantially increase their utility.

Abstract: An Internet-based well data mapping system includes a web-based server computer operably associated with the Internet having an operating system, a processor, a memory, a well data file for receiving well information data and a predetermined well equipment graphic data file template with predetermined well information data fields associated therewith. Well information data mapping software is operably associated with the web-based server computer for interactively displaying at least a portion of the well information data in one of the data fields of the well equipment graphic data file template over the Internet.

Abstract: In one embodiment the invention comprises a method for generating a log of a subsurface formation, in which data from well logging measurements are utilized to derive a relationship between porosity and irreducible water saturation for the formation and the derived relationship between porosity and irreducible water saturation is applied to a porosity log of the subsurface formation to generate a log of irreducible water saturation. In another embodiment the invention comprises a method for calculating a theoretical water saturation log for a subsurface formation which utilizes a relationship based on porosity, irreducible water saturation and height above the petroleum-water contact level.

Abstract: A method and apparatus for surveying a subterranean borehole is disclosed which uses two sets of accelerometers joined by a joining structure which prevents relative rotation between the two sets, the whole apparatus being arranged to permit movement along a borehole to one or more survey positions. Each set of accelerometers measures the gravity in at least two directions at its respective positions, and then from these measured values it is possible to calculate the borehole inclination and azimuth. The present invention is particularly suitable for use in areas with high magnetic interference, or for measuring boreholes with low inclinations. Tests of the present invention shows that an accuracy similar to that obtained by gyro surveys was achievable.

Abstract: A method of compensating for seismic receiver motion in a marine seismic survey wherein at least one receiver is towed behind a moving seismic vessel comprises producing an acoustic energy wave at a seismic source, and recording the reflection arrival time t2 of the acoustic energy wave at the one receiver. The offset x between the source and the one receiver is determined. The normal moveout velocity V for the acoustic energy, and the velocity VB of the seismic vessel are also estimated. A corrected reflection arrival time t1 , of the acoustic energy wave is then determined by applying a time correction to the recorded reflection arrival time t2. The time correction is a function of the offset x, the normal moveout velocity V, and the velocity VB of the seismic vessel. The method is applicable to a plurality of receivers, whether the receivers are arranged in a single sensor acquisition system or hardwired to form receiver groups.

Abstract: A method of determination of fluid pressures in a subsurface region of the earth uses seismic velocities and calibrations relating the seismic velocities to the effective stress on the subsurface sediments. The seismic velocities may be keyed to defined seismic horizons and may be obtained from many methods, including velocity spectra, post-stack inversion, pre-stack inversion, VSP or tomography. Overburden stresses may be obtained from density logs, relations between density and velocity, or front inversion of potential fields data. The seismic data may be P-P, P-S, or S-S data. The calibrations may be predetermined or may be derived from well information including well logs and well pressure measurements. The calibrations may also include the effect of unloading. The determined pressures may be used in the analysis of fluid flow in reservoirs, basin and prospect modeling and in fault integrity analysis.

Abstract: Methods are provided for downhole sensing and flow control utilizing neural networks. In a described embodiment, a temporary sensor is positioned downhole with a permanent sensor. Outputs of the temporary and permanent sensors are recorded as training data sets. A neural network is trained using the training data sets. When the temporary sensor is no longer present or no longer operational in the well, the neural network is capable of determining the temporary sensor's output in response to the input to the neural network of the permanent sensor's output.