Abstract: Nuclear magnetic resonance measurement of a medium are made using a tool with a static magnetic field having a gradient. The nuclear spins of the medium are magnetically polarized using the static magnetic field. Data are acquired from at least three sensitive volumes of the medium using an interleaved sequence of pulses at three different non-overlapping frequencies. At each frequency, a number of sub-sequences of a saturation pulse, a recovery pulse and at least one refocusing pulse are used. The saturation times between the saturation pulse and the recovery pulse for the sub-sequences are selected from a distribution of values between a minimum time to a maximum time to enable determination of T1 and T2 spectra over a wide range of values. Repetitions of sub-sequences having the same saturation at one or more frequencies may be carried out with phase alternation of the recovery pulse phases.

Abstract: The excitation and/or refocusing pulses used in a CPMG sequence have a nonlinear phase and an envelope with no zero crossings and a corresponding frequency spectrum with sidelobes suppressed. As a result of this, peak power requirements are reduced. Pulse shaping is used for reducing the peak power requirements of a NMR logging tool.

Abstract: The present invention provides a novel use of a material having a high internal magnetostrictive damping and/ or using material with explicitly low magnetostriction as a NMR probe core material. The probe structural geometry facilitates the use of material, which has a relatively low magnetic permeability.

Abstract: NMR data are acquired with variable spacing between refocusing pulses, giving data with a variable interecho time TE. Under certain conditions, diffusion effects can be neglected and data acquired with a multiple TE spacing may be used to obtain a T2 distribution with increased resolution and reduced power requirements. In gas reservoirs, the maximum TE may be determined from diffusion considerations using a dual wait time pulse sequence and this maximum TE is used to acquire data with dual TE. By proper selection of TE, echos can be obtained with significantly reduced ringing.

Abstract: NMR data are acquired with variable spacing between refocusing pulses, giving data with a variable interecho time TE. Under certain conditions, diffusion effects can be neglected and data acquired with a multiple TE spacing may be used to obtain a T2 distribution with increased resolution and reduced power requirements. In gas reservoirs, the maximum TE may be determined from diffusion considerations using a dual wait time pulse sequence and this maximum TE is used to acquire data with dual TE.

Abstract: Nuclear magnetic resonance measurement of a medium are made using a tool with a static magnetic field having a gradient. The nuclear spins of the medium are magnetically polarized using the static magnetic field. Data are acquired from at least three sensitive volumes of the medium using an interleaved sequence of pulses at three different non-overlapping frequencies. At each frequency, a number of sub-sequences of a saturation pulse, a recovery pulse and at least one refocusing pulse are used. The saturation times between the saturation pulse and the recovery pulse for the sub-sequences are selected from a distribution of values between a minimum time to a maximum time to enable determination of T1 and T2 spectra over a wide range of values. Repetitions of sub-sequences having the same saturation at one or more frequencies may be carried out with phase alternation of the recovery pulse phases.

Abstract: The present invention provides an apparatus and method for minimizing movement of a drill string during MWD with vibration-sensitive instruments comprising conveying a drill string into a borehole with a sensor mounted on the drill string for sensing a parameter of interest of a formation. A clocked controller is disposed on the drill string for controlling timing of the sensor; and a second clocked controller is disposed at a surface location. During drilling operations, the clocked controllers are synchronized such that the surface controller is performing certain tasks in timed sequence with the sensor even though the surface controller is not connected to the sensor.

Abstract: Nuclear magnetic resonance measurement of a medium are made using a tool with a static magnetic field having a gradient. The nuclear spins of the medium are magnetically polarized using the static magnetic field. Data are acquired from at least three sensitive volumes of the medium using an interleaved sequence of pulses at three different non-overlapping frequencies. At each frequency, a number of sub-sequences of a saturation pulse, a recovery pulse and at least one refocusing pulse are used. The saturation times between the saturation pulse and the recovery pulse for the sub-sequences are selected from a distribution of values between a minimum time to a maximum time to enable determination of T1 and T2 spectra over a wide range of values. Repetitions of sub-sequences having the same saturation at one or more frequencies may be carried out with phase alternation of the recovery pulse phases.

Abstract: A NMR device is presented that includes a drill collar having non-rotating sleeve containing permanent magnets. The non-rotating sleeve is clamped against a borehole wall and decoupled from drilling vibrations during NMR measurements. The transmitter and receiver are located on the rotating part of the drill collar. Alternatively the permanent magnets and the RF receiver antenna and/or receiver electronics are placed on the non-rotating sleeve which is clamped against the borehole wall and decoupled from drilling vibrations, with the transmitting antenna located on the rotating drill collar. Alternatively a non-rotating stabilizer is provided above or below a NMR sensor. A stabilizer is activated to stabilize the rotating NMR sensor located on the drilling collar in the bore hole.

Abstract: An expert system is included in a downhole processor designed to acquire and process NMR data downhole in real time. The downhole processor controls the acquisition of the NMR data based at least in part on instructions transmitted downhole from a surface location and at least in part on evaluation of downhole conditions by the expert system. The downhole conditions include drilling operation conditions (including motion sensors) as well as lithology and fluid content of the formation obtained from other MWD data. The wait time, number of echos, number of repetitions of an echo sequence, interecho time, bandwidth and shape of the tipping and refocusing pulses may be dynamically changed. Data processing is a combination of standard evaluation techniques. Selected data and diagnostics are transmitted uphole. The expert system may be implemented as a two stage neural net. The first stage does the formation evaluation and the second stage controls the NMR pulse sequence.

Abstract: An MWD method and apparatus for determining parameters of interest in a formation has a sensor assembly mounted on a slidable sleeve slidably coupled to a longitudinal member, such as a section of drill pipe. When the sensor assembly is held in a non-rotating position, for instance for obtaining the measurements, the longitudinal member is free to rotate and continue drilling the borehole, wherein downhole measurements can be obtained with substantially no sensor movement or vibration. This is particularly useful in making NMR measurements due to their susceptibility to errors due caused by tool vibration. In addition, the substantially non-rotating arrangement of sensors makes it possible to efficiently carry out VSPs, reverse VSPs and looking ahead of the drill bit. A clamping device is used, for instance, to hold the sensor assembly is held in the non-rotating position.

Abstract: The present invention provides an apparatus and method for minimizing movement of a drill string during MWD with vibration-sensitive instruments comprising conveying a drill string into a borehole with a sensor mounted on the drill string for sensing a parameter of interest of a formation. A clocked controller is disposed on the drill string for controlling timing of the sensor; and a second clocked controller is disposed at a surface location. During drilling operations, the clocked controllers are synchronized such that the surface controller is performing certain tasks in timed sequence with the sensor even though the surface controller is not connected to the sensor.

Abstract: An MWD method and apparatus for determining parameters of interest in a formation has a sensor assembly mounted on a slidable sleeve slidably coupled to a longitudinal member, such as a section of drill pipe. When the sensor assembly is held in a non-rotating position, for instance for obtaining the measurements, the longitudinal member is free to rotate and continue drilling the borehole, wherein downhole measurements can be obtained with substantially no sensor movement or vibration. This is particularly useful in making NMR measurements due to their susceptibility to errors due caused by tool vibration. In addition, the substantially non-rotating arrangement of sensors makes it possible to efficiently carry out VSPs, reverse VSPs and looking ahead of the drill bit. A clamping device is used, for instance, to hold the sensor assembly is held in the non-rotating position.

Abstract: A method and apparatus for protecting a sensor from impact and abrasion while drilling a borehole including a drill collar having a section of electrically non-conductive material, such as a composite material. The electrically non-conductive material has a rugged structural strength for conveying required drilling operation torque and load. The sensor which, for example, induces an RF field, is located inside the drill collar within the section of electrically non-conductive material wherein the sensor is protected from impact and abrasion while drilling a borehole without interference to the electromagnetic energy. The sensor is located, for example, within a load bearing section of the drill collar. Alternatively, the sensor is located inside a removable probe positioned inside the fluid channel through the drill collar. Stabilizers are used for stabilizing the probe within the channel.

Abstract: In general, the present invention provides a modular drilling assembly having a module for contactless power and data transfer over a nonconductive gap between rotating and non-rotating members of a steering module. The gap usually contains a non-conductive fluid, such as drilling fluid, or oil for operating hydraulic devices in the downhole tool. The downhole tool in one embodiment is a modular drilling assembly wherein a drive shaft is rotated by a downhill motor to rotate a drill bit attached to the bottom end of the drive shaft. A substantially non-rotating sleeve around the drive shaft includes at least one electrically-operated device. The drilling assembly is modular in that it includes at least one steering module at the bottom end of the drilling assembly that has at least one steering device module that provides power to the force application member.

Abstract: The present invention provides a drilling assembly for drilling deviated wellbores. The drilling assembly includes a drill bit at the lower end of the drilling assembly. A drilling motor provides the rotary power to the drill bit. A bearing assembly of the drilling motor provides lateral and axial support to the drill shaft connected to the drill bit. A steering device is integrated into drilling motor assembly. The steering device contains a plurality of force application members disposed at an outer surface of the drilling motor assembly Each force application member is adapted to move between a normal position and a radially extended position to exert force on the wellbore interior when in extended position. A power unit in the housing provides pressurized fluid to the force application members. A control device for independently operating each of the force application members is disposed in the drilling motor assembly.

Abstract: An NMR logging apparatus and method are provided including an antenna having compensation for magnetostrictive ringing. The antenna comprises at least one inductive winding and a core having a first portion having positive magnetostriction in the presence of a radio frequency magnetic field, and a second portion having negative magnetostriction in the presence of the radio frequency magnetic field. The positive and negative portions may be tiles shaped as polygonal cylinders arranged with alternating positive and negative tiles forming at least one layer of a matrix, or the portions may be constructed using ferrite powder fixed in epoxy and shaped in polygonal cylinders.

Abstract: In general, the present invention provides a modular drilling assembly having a module for contactless power and data transfer over a nonconductive gap between rotating and non-rotating members of a steering module. The gap usually contains a non-conductive fluid, such as drilling fluid, or oil for operating hydraulic devices in the downhole tool. The downhole tool in one embodiment is a modular drilling assembly wherein a drive shaft is rotated by a downhill motor to rotate a drill bit attached to the bottom end of the drive shaft. A substantially non-rotating sleeve around the drive shaft includes at least one electrically-operated device. The drilling assembly is modular in that it includes at least one steering module at the bottom end of the drilling assembly that has at least one steering device module that provides power to the force application member.

Abstract: A drilling system utilizing the drilling fluid in a borehole to drive an apparatus to generate a high-pressure jet of fluid to facilitate the drilling operation. A pressure intensifier disposed between a drilling motor and the drill bit generates high pressure fluid jet. The drilling motor rotates the pressure intensifier. Fluid enters a high pressure chamber in the pressure intensifier at selected location during each rotation. A piston in the pressure intensifier discharges the fluid from the high pressure chamber to the drill bit bottom at a high pressure. An electrically-operated pulse frequency control device generates fluid pulses of at least two frequencies, each such frequency defining a bit of a binary system.

Abstract: An MWD method and apparatus for determining parameters of interest in a formation has a sensor assembly mounted on a slidable sleeve slidably coupled to a longitudinal member, such as a section of drill pipe. When the sensor assembly is held in a non-rotating position, for instance for obtaining the measurements, the longitudinal member is free to rotate and continue drilling the borehole, wherein downhole measurements can be obtained with substantially no sensor movement or vibration. This is particularly useful in making NMR measurements due to their susceptibility to errors due caused by tool vibration. In addition, the substantially non-rotating arrangement of sensors makes it possible to efficiently carry out VSPs, reverse VSPs and looking ahead of the drill bit. A clamping device is used, for instance, to hold the sensor assembly is held in the non-rotating position.