Abstract: Apparatus and method for determining pressure in a well is provided. A sensor for determining the rate of change of pressure in a well comprises: a first cavity body defining an enclosed volume, a portion of one wall of the cavity body being constituted by a pressure sensitive membrane capable of exposure to the well pressure so as to be responsive thereto; and a first capillary connected to the first cavity body at one end and being open to the well pressure at the other end so as to provide pressure communication between the well pressure and the interior of the first cavity body; wherein a length of the first capillary, an internal diameter of the first capillary, and the volume of the first cavity body are such that the sensor has a predetermined pressure response that comprises an input minus a low-pass filtered version of the input, and a predetermined time constant.

Abstract: A method for determining a formation electrical property under a sea floor includes obtaining measurement data using a receiver having an impedance lower than an impedance of seawater at a measurement site; correcting the measurement data to obtain corrected data corresponding to data that would have been acquired using a receiver having an impedance matched with the impedance of the seawater; and deriving the formation property from the corrected data.

Abstract: A method for determining formation electrical properties includes deploying one or more receivers for electromagnetic logging; obtaining measurement data indicative of the formation electrical properties using the deployed receivers; correcting the measurement data for receiver imperfection; and inverting the corrected measurement data to obtain one or more parameters of formation electrical properties.

Abstract: Apparatus and method for determining pressure in a well is provided. A sensor for determining the rate of change of pressure in a well comprises: a first cavity body defining an enclosed volume, a portion of one wall of the cavity body being constituted by a pressure sensitive membrane capable of exposure to the well pressure so as to be responsive thereto; and a first capillary connected to the first cavity body at one end and being open to the well pressure at the other end so as to provide pressure communication between the well pressure and the interior of the first cavity body; wherein a length of the first capillary, an internal diameter of the first capillary, and the volume of the first cavity body are such that the sensor has a predetermined pressure response that comprises an input minus a low-pass filtered version of the input, and a predetermined time constant.

Abstract: A receiver for electromagnetic measurements includes a polyhedron structure having m faces, where m?4 and m?6: n electrodes each disposed on one face of the polyhedron structure, wherein 3?n?m; and at least one circuitry connected to the n electrodes for signal measurement. A method for electromagnetic measurements includes obtaining a plurality of electric current measurements using a plurality of electrodes each disposed on a surface of a polyhedron receiver, wherein the plurality of electric current measurements comprise at least three different measurements; and determining electric field components in a three dimensional space from the plurality of electric current measurements by using a number of matrices that correlate orientations of surfaces of the polyhedron receiver to a coordinate system in the three dimensional space.

Abstract: A method for determining formation electrical properties includes deploying one or more receivers for electromagnetic logging; obtaining measurement data indicative of the formation electrical properties using the deployed receivers; correcting the measurement data for receiver imperfection; and inverting the corrected measurement data to obtain one or more parameters of formation electrical properties.

Abstract: An electromagnetic receiver includes at least one sensor for measuring electromagnetic signals, and a calibration antenna configured to generate an electromagnetic signal at a first frequency.

Abstract: A method for determining a formation electrical property under a sea floor includes obtaining measurement data using a receiver having an impedance lower than an impedance of seawater at a measurement site; correcting the measurement data to obtain corrected data corresponding to data that would have been acquired using a receiver having an impedance matched with the impedance of the seawater; and deriving the formation property from the corrected data.

Abstract: A receiver for electromagnetic measurements includes a polyhedron structure having m faces, where m?4 and m?6: n electrodes each disposed on one face of the polyhedron structure, wherein 3?n?m; and at least one circuitry connected to the n electrodes for signal measurement. A method for electromagnetic measurements includes obtaining a plurality of electric current measurements using a plurality of electrodes each disposed on a surface of a polyhedron receiver, wherein the plurality of electric current measurements comprise at least three different measurements; and determining electric field components in a three dimensional space from the plurality of electric current measurements by using a number of matrices that correlate orientations of surfaces of the polyhedron receiver to a coordinate system in the three dimensional space.

Abstract: The invention relates to monitoring of fluid-filled domains in various media including, for example, subterranean formations, construction elements, bones. Claimed are a method for determining characteristic sizes of a fluid-filled crack in a medium and a system for implementation thereof. In accordance with this method, oscillations of the fluid-filled crack are registered. Wave characteristics of standing interface waves propagating along the fluid-filled crack surfaces are determined based on the registered oscillations taking medium and fluid properties into account. The fluid-filled crack characteristic sizes are calculated based on the determined wave characteristics of the standing interface waves.

Abstract: Hydraulic fracture dimensions and, optionally, fracture closure pressure and time are determined by adding particulate matter that discharges to create an acoustic signal to the proppant, allowing the particulate matter to discharge, and detecting the acoustic signal with geophones or accelerometers. The particulate matter may be spheres or fibers. The discharge may be explosion, implosion, detonation, or rapid combustion or ignition. The discharge may be triggered by fracture closure or by chemical reaction.

Abstract: The invention describes a method of cement lining a wellbore to enable a fixed sensor internal of the lining to sense characteristics of the external formations surrounding the wellbore using, at the region of the sensor position, a permeability changing device before completion of setting of the cement to create, in use, a permanent fluid communication through the cement lining between the external formation and the sensor.

Abstract: A method of monitoring gas in a downhole environment is discussed which provides downhole a mid-infrared light emitting diode, operates the diode to transmit respective infrared signals on a first optical path extending from the diode through a downhole gas sample and a second optical path extending from the diode through a reference gas sample, detects the transmitted infrared signals, and determines the concentration of a component of the downhole gas sample from the detected signals.

Abstract: A method of monitoring gas in a downhole environment is discussed which provides downhole a mid-infrared light emitting diode, operates the diode to transmit respective infrared signals on a first optical path extending from the diode through a downhole gas sample and a second optical path extending from the diode through a reference gas sample, detects the transmitted infrared signals, and determines the concentration of a component of the downhole gas sample from the detected signals.

Abstract: The invention relates to monitoring of fluid-filled domains in various media including, for example, subterranean formations, construction elements, bones. Claimed are a method for determining characteristic sizes of a fluid-filled crack in a medium and a system for implementation thereof. In accordance with this method, oscillations of the fluid-filled crack are registered. Wave characteristics of standing interface waves propagating along the fluid-filled crack surfaces are determined based on the registered oscillations taking medium and fluid properties into account. The fluid-filled crack characteristic sizes are calculated based on the determined wave characteristics of the standing interface waves.

Abstract: Hydraulic fracture dimensions and, optionally, fracture closure pressure and time are determined by adding particulate matter that discharges to create an acoustic signal to the proppant, allowing the particulate matter to discharge, and detecting the acoustic signal with geophones or accelerometers. The particulate matter may be spheres or fibers. The discharge may be explosion, implosion, detonation, or rapid combustion or ignition. The discharge may be triggered by fracture closure or by chemical reaction.

Abstract: A method of cement lining a wellbore to enable a fixed sensor internal of the lining to sense characteristics of the external formations surrounding the wellbore, wherein, at the region of the sensor position, means are utilised before completion of setting of the cement to create, in use, a permanent fluid pressure connection through the cement lining between the external formation and the sensor.

Abstract: There is provided a data acquisition apparatus for use in a wellbore, having a receiver attached to an elongate electrical connector for conveying signals from downhole to surface, and a plurality of sensing devices adapted to be positioned downhole in spaced apart positions remote from the receiver, so as to form an array of sensing devices. The receiver includes a transmitter so as to allow two-way travel of signals within the wellbore. The invention is particularly of use when acquiring data in near-horizontal wells, or horizontal wells. Data acquired by one sensing device is transmitted to a receiver on a neighboring sensing device for transmittal from the neighboring sensing device to a next neighbour in the array. Data signals are thus relayed along the array of sensing devices until the last sensing device in the array transmits all acquired data to the receiver. The spacing between the individual sensing devices is regular and ranges from 3 meters to 100 meters.