Abstract: Hydraulic fracturing of a subterranean hydrocarbon reservoir is carried out using an aqueous wellbore fluid which is an aqueous solution of a surfactant which has the formula (R1—X)nZ, where R1 is an aliphatic group comprising a C10-C25 principal straight chain bonded at a terminal carbon atom thereof to X, and comprising at least one C1-C6 side chain. X is a charged head group, Z is a counterion, and n is an integer which ensures that the surfactant is charge neutral. The surfactant reversibly thickens the aqueous solution such that the wellbore fluid is a viscoelastic gel. The viscoelastic gel breaks and undergoes a reduction in viscosity within the reservoir and surfactant from the broken gel mixes with hydrocarbon in the reservoir.

Abstract: A method and system are provided for investigating a gas-liquid fluid mixture as it is conveyed in a conduit having a first constriction region providing a reduced conduit cross section. The method and system include inducing the mixture to exhibit swirling flow in the first constriction region, thereby separating the liquid from the gas, and determining one or more properties of the fluid in the first constriction region.

Abstract: Methods and apparatus facilitating radial profiling of formation mobility are disclosed. Radial profiling of formation mobility aids in an optimal completion of a well for enhanced production. Some aspects of the present invention provide a technique for radial profiling of formation mobility based on inverting differences between a Stoneley radial profile of horizontal shear slowness and a dipole radial profile of vertical shear slowness for a reservoir interval.

Abstract: A microseismic method of monitoring fracturing operation or other microseismic events in hydrocarbon wells is described using the steps of obtaining multi-component signal recordings from a single monitoring well in the vicinity of a facture or event; and rotating observed signals such that they become independent of at least one component of the moment tensor representing the source mechanism and performing an inversion of the rotated signals to determine the remaining components.

Abstract: A computer-implemented method is provided that automatically characterizes and verifies stationarity of a training image for use in multipoint geostatistical analysis. The stationarity is preferably characterized by statistical measures of orientation stationarity, scale stationarity, and category distribution stationarity.

Abstract: Methods and pulse sequences for facilitating nuclear magnetic resonance (NMR) measurements in grossly inhomogeneous fields. Methods and pulse sequences according to the invention may be used to accurately measure variables such as transverse relaxation time, longitudinal relaxation time, and diffusion, without the need for data at long recovery time, thereby allowing for faster measurements. In addition, methods and pulse sequences according to embodiment of the invention may allow simultaneous encoding of information in both the amplitude and the shape of echoes, so as to allow a single-shot measurement of multiple variables, e.g., both transverse relaxation time (from the decay of echo amplitudes) and longitudinal relaxation time (from the echo shape). CPMG detection may be used to overcome the often limited signal-to-noise ratio in grossly inhomogeneous fields.

Abstract: The invention concerns an aqueous delayed-gelation solution for use in hydrocarbon wells. According to the invention, the aqueous delayed-gelation solution a dissolved metal salt which, in use, hydrolyses to form a gel, wherein the solution contains suspended inorganic particles and the method comprises the steps of—providing the aqueous delayed-gelation solution, and—injecting the solution into the hydrocarbon well, whereby the suspended inorganic particles reduce or block the flow of the delayed-gelation solution to relatively low permeability formation zones thereby selectively placing the solution in a relatively high permeability formation zone.

Abstract: A casing position locator for detecting structural features of a borehole casing, the locator including: a plurality of field generators for generating respective dynamic magnetic fields which combine to provide a dynamic test magnetic field to interact with the casing, where the test field includes a magnetic field null point located where the respective dynamic magnetic fields substantially cancel each other out; and a sensor for detecting a change in the position of the null point, relative to the sensor, due to the interaction.

Abstract: Methods and systems are described for determining a flow rate of a gas-liquid fluid mixture in a conduit. In the described systems and methods, the fluid mixture is conditioned so that the liquid in the mixture is separated from the gas in the mixture. Properties of the conditioned flow may then be measured to determine the flow rate. In an embodiment of the invention, the hold up of the separated liquid is measured; the velocity of the separated liquid is measured; the velocity of the separated gas is measured; and the flow rate of the gas-liquid fluid mixture is determined from the hold up and the velocities.

Abstract: A self-contained micro-scale gas chromatography system that includes a plurality of gas chromatography components arranged on a micro-fluidic platform with nearly zero dead volume “tubeless” fluidic connections for the gas chromatography components. The micro-fluidic platform includes a plurality of flow channels that provide fluid flow paths for a sample, carrier gas and waste gas through and among the micro-fluidic platform and the plurality of gas chromatography components. The system may also include an on-board supply of carrier gas and on-board waste management, as well as a thermal management scheme making the system suitable for use in oil and gas wells and also other remote environments.

Abstract: Sensors located in the vicinity of a hydrocarbon-producing well receive power and communicate with one or more hubs located in the well or at the outer surface of a casing by means of elastodynamic waves. Each hub incorporates a plurality of transducers which permit focusing of the emitted elastodynamic waves. In order to concentrate the energy on a single sensor, or a group of sensors arranged in a cluster. Hubs and sensors communicate by exchanging, modulated elastodynamic waves. Sensors belonging to a cluster may transmit, properly time-shifted elastodynamic waves, in order to collectively focus their energy in the direction of a hub. Time synchronization between the sensors within a cluster may be accomplished by means of electromagnetic fields which travel much faster than elastodynamic waves, but can only propagate over short distances in typical formations.

Abstract: A production logging tool for measuring at least one property of a surrounding fluid in a wellbore, comprising a shaft and a rotatable member coupled to the shaft, the rotatable member comprising a sensor component, the arrangement being such that on rotation of the member the sensor moves in a path transverse to the length of the shaft.

Abstract: An LuAP scintillation detector and a method for improving the light output and uniformity of an LuAP scintillator crystal is provided, wherein the method includes disposing the scintillator crystal in a predetermined environment at a threshold temperature to generate an initial scintillator crystal, annealing the initial scintillator crystal in the predetermined environment at the threshold temperature to create an annealed scintillator crystal and cooling the annealed scintillator crystal in the predetermined environment to a final temperature.

Abstract: An iterative process is described for obtaining a finite impulse filter to remove noise from seismic data through an iterative process with constraints on the filter applied in both, the original space-time and the transform frequency wave number at each iteration step.

Abstract: A system for controlling gas in a subsea drilling operation is disclosed in one embodiment. The system includes a subsea blow-out preventer, riser coupled to the blow-out preventer, a gas sensor, a controller, and a signal pathway. The gas sensor is configured for placement below the riser and configured to contact wellbore fluids during normal drilling operation. The controller configured to automatically cause manipulation the blow-out preventer based upon information from the gas sensor. The signal pathway couples the gas sensor with the controller.

Abstract: Systems and methods are disclosed for measuring densities and flow rates of gas-liquid fluid mixtures. In the systems and methods, the fluid mixture is caused to exhibit swirling flow as it flows through a conduit that includes a constriction, a first pressure difference is measured between two vertically-spaced measurement positions in the conduit, a second pressure difference is measured between two horizontally-spaced measurement positions in the conduit, the first horizontally-spaced measurement position being at the constriction region and the second horizontally-spaced measurement position being upstream or downstream of the constriction region, and one or more of the pressure differences is used to determine a density or a flow rate of the gas-liquid fluid mixture.

Abstract: A ruggedized pressure sensor is described for high pressure applications having a top part of hard material with a surface adapted to deform when exposed to pressure, transducers to transform deformation of the surface into a signal proportional to the pressure, and a base part of hard material, wherein the base part has one or more openings.

Abstract: A method of filtering seismic signals is described using the steps of obtaining the seismic signals generated by activating a seismic source and recording signals emanating from the source at one or more receivers; defining a source signature deconvolution filter to filter the seismic signal, wherein the filter is scaled by a frequency-dependent term based on an estimate of the signal-to-noise (S/N) based on the spectral power of a signal common to a suite of angle-dependent far-field signatures normalized by the total spectral power of the signatures within the angular suite and performing a source signature deconvolution using the source signature deconvolution filter.

Abstract: An apparatus and methods that can be used to determine various qualitative parameters of an earth formation from nuclear magnetic resonance (NMR) measurements. One embodiment provides a method of NMR-based remote sensing in which a nuclear spins in fluid of interest are encoded while inside an earth formation and then withdrawn into a tool module and analyzed by a sensor located in the tool module. Separate encoding and detection systems may be used, allowing each system to be independently optimized. In particular, because detection of the encoded spins may occur while the spins are inside the detector system, rather than within the earth formation (where they are encoded), the detector system may be constructed to employ a highly uniform magnetic field. This may facilitate various NMR measurements.

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.