A downhole tool, comprising: a tool mandrel; a pad comprising a transmitter operable to transmit an electric current into a formation and a receiver operable to receive at least a portion of the electric current from transmitter; an extension from the tool mandrel that couples pad to tool mandrel; and a signal filter positioned in the downhole tool to suppress passage of mandrel leakage current that passes through tool mandrel to pad. A method of resistivity imaging, comprising: disposing a downhole tool into borehole; transmitting a current into formation surrounding the borehole with a transmitter that is extended from tool mandrel of the downhole tool towards borehole wall; and recording at least a portion of the current that returns to receiver of downhole tool, wherein a signal filter suppress passages of mandrel leakage current that passes through the tool mandrel to a pad on which the transmitter is disposed.

A device for centering a sensor assembly in a bore comprises a first support member and a second support member axially spaced apart along a longitudinal axis of the device, and a plurality of arm assemblies connected between the first and second support members. Each arm assembly comprises a first arm pivotally connected to the first support member by a first pivot joint having a first pivot axis, a second arm pivotally connected to the second support member by a second pivot joint having a second pivot axis, a third arm connected between the first and second arms, the third arm pivotally connected to the first arm by a third pivot joint having a third pivot axis, and the third arm pivotally connected to the second arm by a fourth pivot joint having a fourth pivot axis. A third support member is positioned axially between the first and second support members, and the third arm is pivotally connected to the third support member by a fifth pivot joint having a fifth pivot axis coincident with and orthogonal to the longitudinal axis. The third arm extends across the longitudinal axis between the third pivot axis and the fourth pivot axis, so that in use each arm assembly contacts opposite sides of the bore to centralise the sensor assembly in the bore.

In some embodiments, a method for locally lumped equation of state fluid characterization can include determining a set of components for the material balance calculations for a plurality of grid blocks of a reservoir. The plurality of grid blocks can experience different recovery methods between them. Lumping schemes can be determined for the plurality of grid blocks. Phase behavior calculations can be performed on the plurality of grid blocks, wherein different lumping schemes can be used across the plurality of grid blocks.

In some embodiments, a method for locally lumped equation of state fluid characterization can include determining a set of components for the material balance calculations for a plurality of grid blocks of a reservoir. The plurality of grid blocks can experience different recovery methods between them. Lumping schemes can be determined for the plurality of grid blocks. Phase behavior calculations can be performed on the plurality of grid blocks, wherein different lumping schemes can be used across the plurality of grid blocks.

An internal structure detection system includes: two kinds of sensors with different operating principles for receiving reflected waves of vibration applied to an inspection target in an investigation area; and a processing apparatus that detects an internal structure of the inspection target by using the sensor data received by the two kinds of sensors. The two kinds of sensors are deployed in the investigation area with different densities, in a distributed manner.

A measurement-while-drilling method and device assesses outburst risk and evaluates gas drainage performance of a coal seam. The device includes a compartment, a pressure sensor, a temperature sensor, a flow sensor, an electromagnetic sensor, an acoustic sensor, a wave velocity measurement module, a monitoring and control module, a power supply and a communication interface. These are installed between a drill bit and an inclinometer or a first drill pipe. Measurements are performed while drilling to obtain a real time gas parameter, lithologic and coal seam information, for on-site assessment of outburst risk. During drill bit replacement, gas pressure, temperature, flow velocity, wave velocity, electromagnetic radiation, and an acoustic signal are recorded in real time, to calculate stress of the coal seam and coal seam outburst risk. On-site measurement is done while drilling without sampling and can use multiple parameters to perform synchronous measurement to obtain a comprehensive evaluation.

A device and method used to correct beamforming of an acoustic phased array in cases of eccentricity of the acoustic device in a tubular. A processor calculates the eccentricity from multiple scan lines and create a geometric model of a well or pipe relative to the device. The processor may correct each scan line's focus and/or angle of incidence at a surface of the well or pipe based on the observed eccentricity.

A hybrid sensing apparatus for collecting data inside a well, the apparatus including an optical cable that acquires a first set of data; and an array of discrete probes connected to each other with an electrical cable. The discrete probes are configured to acquire a second set of data. The apparatus further includes an attachment system attached to the discrete probes and configured to hold the optical cable. The attachment system is configured to expose the optical cable to directly contact the well.

There is provided systems and methods for providing enhanced high definition images of subterranean activities, and structures using migrated data from two independent sources. There are provided systems and methods for imaging hydraulic fracturing and hydraulic fractures and the resultant images of hydraulic fracturing and hydraulic fractures, including the image of the shape of the fracture.

An assembly, method and device are for performing a survey of tubing which is stuck in a borehole. The assembly has a tractor for advancing the assembly along the tubing on an inside thereof; at least one engager connected to the tractor, the engager being configured to couple the assembly to a wall of the tubing, such that a stimulus applied to the tubing, e.g. components of force or manipulation of the tubing, can be communicated to produce a response in a part of the assembly. A detector may detect the response when the assembly is coupled to the wall of the tubing, in order to produce data based on the response for determining a location at which the tubing may, or may not, be subjected to at least one operation for freeing the string or a portion thereof.