Abstract: A system and method for drilling a second well with respect to a first well is disclosed. A first drill string having a known magnetic signature is disposed at a first depth in the first well. A second drill string is used to drill the second well. The second drill string includes a magnetometer that obtains a magnetic measurement of the first drill string during drilling of the second well. A processor uses the obtained magnetic measurement and the magnetic signature of the first drill string to steer the second drill string to drill the second well.

Abstract: A tool for use in a borehole penetrating a formation method and a method for using the tool is disclosed. The tool includes a gyroscope for obtaining a first measurement of a rotation rate of the apparatus and at least one accelerometer for obtaining a second measurement of the rotation rate of the apparatus. A processor generates an estimate of the rotation rate using at least one of the first measurement of rotation rate and the second measurement of rotation rate. The estimate of the rotation rate is sued to determine a rotational position of a formation parameter measurement obtained during rotation of the apparatus in the borehole.

Abstract: A tool for use in a borehole penetrating a formation method and a method for using the tool is disclosed. The tool includes a gyroscope for obtaining a first measurement of a rotation rate of the apparatus and at least one accelerometer for obtaining a second measurement of the rotation rate of the apparatus. A processor generates an estimate of the rotation rate using at least one of the first measurement of rotation rate and the second measurement of rotation rate. The estimate of the rotation rate is sued to determine a rotational position of a formation parameter measurement obtained during rotation of the apparatus in the borehole.

Abstract: In one aspect, an apparatus for treating a formation is disclosed that in one non-limiting embodiment includes a first string for placement in the wellbore that includes a first flow port that enables a treatment fluid to flow from inside the first string to the formation via an annulus between the first string and the formation, a second string for placement in the first string, wherein the second string includes a second flow port that supplies the treatment fluid to the first flow port along a selected radial orientation to direct the treatment fluid in the selected radial direction.

Abstract: A method, system and drilling apparatus for directional drilling are disclosed. A drill bit is located at a downhole end of a drill string in a borehole. A length of the borehole between a surface location and the drill bit at the downhole end of a drill string is determined and an azimuth angle and inclination of the drill bit is obtained. The length of the borehole may be determined by recording an arrival time at a downhole location of an acoustic pulse travelling from a surface location to the downhole location and determines the travel time and borehole length therefrom. A downhole processor determines a position and orientation of the drill bit from the determined length, azimuth angle and inclination and alters a steering parameter of the drill bit using the determined position and orientation of the drill bit to obtain a selected trajectory for drilling the borehole.

Abstract: A system method and computer-readable medium for correcting measurements obtained by a down hole tool for residual measurement errors is disclosed. A down hole tool having at least two directional field sensors is disposed in a borehole. The at least two directional sensors are substantially orthogonal to each other and to a longitudinal axis of the down hole tool. Measurements are obtained from the at least two directional sensors during rotation of the tool by at least 360 degrees around the longitudinal axis of the tool. Residual measurement errors are determined for the obtained measurements, and a quality level of the determined residual measurement errors selected. The determined residual measurement errors are applied to the obtained measurements when the determined residual measurement errors are consistent with the selected quality level.

Abstract: A system and method for drilling a second well with respect to a first well is disclosed. A first drill string having a known magnetic signature is disposed at a first depth in the first well. A second drill string is used to drill the second well. The second drill string includes a magnetometer that obtains a magnetic measurement of the first drill string during drilling of the second well. A processor uses the obtained magnetic measurement and the magnetic signature of the first drill string to steer the second drill string to drill the second well.

Abstract: A method of drilling a well is disclosed. A first estimate is obtained of a location of the well with respect to a reference well at a selected depth. A magnetic measurement is obtained at the selected depth using a sensor. The obtained magnetic measurement is related to a residual magnetic charge distribution in the reference well. An expected value of the magnetic measurement at the selected depth is determined from the residual magnetic charge distribution. A second estimate is obtained of the location of the well using the first estimate of the location, the obtained magnetic measurement and the expected value of the magnetic measurement. A drilling parameter of the well is altered using the second estimate of the location.

Abstract: A drilling system, method and drilling apparatus for determining a parameter of a formation at a downhole location is disclosed. A member having a longitudinal axis is disposed in a borehole at the downhole location. A first magnetometer and a second magnetometer are disposed at an axial location of the member as separate azimuthal locations around the member and oriented tangential to a circumference of circle in a plane transverse to a longitudinal axis of the member. Magnetic fields resulting from a current flowing longitudinally through the member due to a spontaneous potential in the formation are measured to determine the spontaneous potential. The parameter of the formation is determined from the determined spontaneous potential.

Abstract: In one aspect, an apparatus for treating a formation is disclosed that in one non-limiting embodiment includes a first string for placement in the wellbore that includes a first flow port that enables a treatment fluid to flow from inside the first string to the formation via an annulus between the first string and the formation, a second string for placement in the first string, wherein the second string includes a second flow port that supplies the treatment fluid to the first flow port along a selected radial orientation to direct the treatment fluid in the selected radial direction.

Abstract: A system method and computer-readable medium for correcting measurements obtained by a down hole tool for residual measurement errors is disclosed. A down hole tool having at least two directional field sensors is disposed in a borehole. The at least two directional sensors are substantially orthogonal to each other and to a longitudinal axis of the down hole tool. Measurements are obtained from the at least two directional sensors during rotation of the tool by at least 360 degrees around the longitudinal axis of the tool. Residual measurement errors are determined for the obtained measurements, and a quality level of the determined residual measurement errors selected. The determined residual measurement errors are applied to the obtained measurements when the determined residual measurement errors are consistent with the selected quality level.

Abstract: In one aspect, an apparatus for use in a wellbore is provided that in one embodiment includes a sensor having a plurality of spaced conductive contact elements, a sensing member that moves by gravity and contacts at least two contact elements in the plurality of contact elements to create an electrical short between such at least two contact elements and a circuit coupled to the contact elements configured to generate electrical signals in response to the electrical short between the contact elements.

Abstract: A method for surveying a formation includes conveying a survey instrument into the wellbore; measuring one or more parameters of interest relating to a wellbore tubular in the wellbore; and operating the survey instrument after the measured parameter of interest indicates that the wellbore tubular is being tripped out of the wellbore.

Abstract: A drilling system, method and drilling apparatus for determining a parameter of a formation at a downhole location is disclosed. A member having a longitudinal axis is disposed in a borehole at the downhole location. A first magnetometer and a second magnetometer are disposed at an axial location of the member as separate azimuthal locations around the member and oriented tangential to a circumference of circle in a plane transverse to a longitudinal axis of the member. Magnetic fields resulting from a current flowing longitudinally through the member due to a spontaneous potential in the formation are measured to determine the spontaneous potential. The parameter of the formation is determined from the determined spontaneous potential.

Abstract: A method, system and drilling apparatus for directional drilling are disclosed. A drill bit is located at a downhole end of a drill string in a borehole. A length of the borehole between a surface location and the drill bit at the downhole end of a drill string is determined and an azimuth angle and inclination of the drill bit is obtained. The length of the borehole may be determined by recording an arrival time at a downhole location of an acoustic pulse travelling from a surface location to the downhole location and determines the travel time and borehole length therefrom. A downhole processor determines a position and orientation of the drill bit from the determined length, azimuth angle and inclination and alters a steering parameter of the drill bit using the determined position and orientation of the drill bit to obtain a selected trajectory for drilling the borehole.

Abstract: A method of drilling a well is disclosed. A first estimate is obtained of a location of the well with respect to a reference well at a selected depth. A magnetic measurement is obtained at the selected depth using a sensor. The obtained magnetic measurement is related to a residual magnetic charge distribution in the reference well. An expected value of the magnetic measurement at the selected depth is determined from the residual magnetic charge distribution. A second estimate is obtained of the location of the well using the first estimate of the location, the obtained magnetic measurement and the expected value of the magnetic measurement. A drilling parameter of the well is altered using the second estimate of the location.

Abstract: In one aspect, an apparatus for use in a wellbore is provided that in one embodiment includes a sensor having a plurality of spaced conductive contact elements, a sensing member that moves by gravity and contacts at least two contact elements in the plurality of contact elements to create an electrical short between such at least two contact elements and a circuit coupled to the contact elements configured to generate electrical signals in response to the electrical short between the contact elements.

Abstract: A method to correct for a systematic error of a sensor having a plurality of accelerometers configured to measure gravitational acceleration, the method including: rotating the plurality of accelerometers about a first axis; obtaining a first set of calibration measurements from the plurality of accelerometers from the rotation about the first axis; determining a first systematic error for each accelerometer in the plurality using the first set of calibration measurements; and removing the first systematic error from sensor measurements to correct for the systematic error.

Abstract: A two-axis gyroscope used on a bottom hole assembly can be used for determining a rate of rotation about the rotational axis of a BHA. The method takes advantage of possible misalignment of at least one axis of the two axis gyroscope from orthogonality with respect to the rotational axis of the BHA, resulting in the misaligned gyro being sensitive to BHA rotation.

Abstract: A photodiode whose long-wavelength cutoff is in the short-wavelength range (preferably, between ultraviolet and yellowish-green) having reduced temperature sensitivity is used in downhole applications. It may be matched with scintillation devices having an output matched to the response curve of the photodiode for use with nuclear logging devices. The photodiode may also be used in gyroscopes in which light from an LED matched to the photodiode is reflected from a spinning mass.