A method of predicting three-dimensional fracture geometry in a subterranean region of interest is disclosed. The method includes obtaining a strain tensor for the subterranean region of interest, calculating a set of principal strain components from the strain tensor, and determining a strain cyclide from the set of principal strain components. The method further includes calculating a set of quadrimodal fault normal vectors from the strain cyclide and determining an in-plane shear strain magnitude and a shear strain orientation from the set of quadrimodal fault normal vectors.

Some systems and methods of hydraulic fracturing a formation of a borehole include receiving a length-to-radius ratio of a borehole segment of the borehole and determining when the length-to-radius ratio is less than a threshold. Responsive to determining that the length-to-radius ratio is less than the threshold, some systems and methods include predicting a breakdown pressure associated with a formation surrounding the borehole segment based on a length of the borehole segment. Responsive to determining that the length-to-radius ratio is greater than or equal to the threshold, some systems and methods include determining, a characteristic diffusion time associated with a fluid diffusing into the formation surrounding the borehole segment. Some systems and methods include pumping the fluid into the borehole segment to fracture the formation surrounding the borehole segment at the determined breakdown pressure.

In accordance with some embodiments of the present disclosure, systems and methods for an advanced toolface control system for a rotary steerable drilling tool is disclosed. The method includes determining a desired toolface of a drilling tool, calculating a toolface error by determining a difference between a current toolface of the drilling tool and the desired toolface, decoupling a response of a first component of the drilling tool, calculating a correction to reduce the toolface error based on a model of the drilling tool containing information about a source of the toolface error, transmitting a signal to a second component of the drilling tool such that the signal adjusts the current toolface based on the correction, and drilling a wellbore with a drill bit oriented at the desired toolface.

In accordance with some embodiments of the present disclosure, systems and methods for an advanced toolface control system for a rotary steerable drilling tool is disclosed. The method includes determining a desired toolface of a drilling tool, calculating a toolface error by determining a difference between a current toolface of the drilling tool and the desired toolface, decoupling a response of a first component of the drilling tool, calculating a correction to reduce the toolface error based on a model of the drilling tool containing information about a source of the toolface error, transmitting a signal to a second component of the drilling tool such that the signal adjusts the current toolface based on the correction, and drilling a wellbore with a drill bit oriented at the desired toolface.

A method for mapping a cased wellbore, the method comprising providing a cased wellbore; and routing a sensor assembly through said cased wellbore to measure forces applied to said sensor assembly.

A drilling assembly includes a straight housing in which a mud motor assembly is mounted. The mud motor includes a rotor that rotates within a stator. The rotor has an axial centerline substantially parallel with the housing. A drivetrain is coupled between the rotor and a driveshaft. The driveshaft is coupled to a drill head. The driveshaft has a centerline that is non-coincident with (i.e., offset or angled) the axial centerline. The angle between the driveshaft centerline and the axial centerline may be fixed or variable. The angle may be variable in response to an axial force, imparted to the rotor, that is transferred to the driveshaft through the drivetrain. Additional apparatus, systems, and methods are disclosed.

The method of maintaining drill bit advancement in an underground formation that contains shale, including providing an electrical signal from an insulated gap location in a drill string substantially directly behind the bit in the formation, detecting substantial change in a signal as the bit advances, and changing the direction of drilling of the bit as a function of a signal change, to thereby maintain the direction of bit advancement in the formation. A method is disclosed for detecting the existence and direction of adjacent bed boundaries. A short hop transmitter assembly generates a signal that is detected by an associated receiver assembly. The received signal(s) are tied to the azimuthal orientation of the transmitter or receiver and processed to yield the direction and/or the distance of the bed boundary. This information is transmitted to the surface via surface telemetry for real-time control of the drilling assembly to stay within, or to enter, a pay zone.

The method of maintaining drill bit advancement in an underground formation that contains shale, including providing an electrical signal from an insulated gap location in a drill string substantially directly behind the bit in the formation, detecting substantial change in a signal as the bit advances, and changing the direction of drilling of the bit as a function of a signal change, to thereby maintain the direction of bit advancement in the formation. A method is disclosed for detecting the existence and direction of adjacent bed boundaries. A short hop transmitter assembly generates a signal that is detected by an associated receiver assembly. The received signal(s) are tied to the azimuthal orientation of the transmitter or receiver and processed to yield the direction and/or the distance of the bed boundary. This information is transmitted to the surface via surface telemetry for real-time control of the drilling assembly to stay within, or to enter, a pay zone.

A downhole sensor system may include at least two accelerometers having at least two axes of measurement. The at least two accelerometers may include a first accelerometer in a first position and a second accelerometer in a second position. A first axis of the second accelerometer may be substantially coaxial with a first axis of the first accelerometer and a second axis of the second accelerometer may be parallel to and offset from a second corresponding axis of the first accelerometer. The downhole sensor system may further include at least one processor, and at least one non-transitory computer-readable storage medium storing instructions thereon that when executed by the at least one processor may cause the processor to measure a first acceleration from the first accelerometer and measure a second acceleration from the second accelerometer. When executed by the at least one processor the instructions may also cause the processor to calculate acceleration properties of the downhole sensor system based on acceleration measurements of the first accelerometer and the second accelerometer.

Techniques for determining trajectories for a plurality of wells while avoiding collision between wells are presented. The techniques can include determining a zone of uncertainty for individual wells of the plurality of wells, determining a minimum separation factor for individual wells of the plurality of wells, determining a gradient of a separation factor for at least one pair of wells the plurality of pairs of wells, updating a nudge position for at least one well, and providing nudge positions for the individual wells of the plurality of wells.