In some embodiments, an apparatus and a system, as well as a method and an article, may operate to transmit and receive data. Transmission may comprise transforming larger values of acquired data into smaller values of transformed data using a transform defined by a seed value selected to reduce digital pulse position modulation transmission time for the acquired data. Additional activities include digital pulse position modulating the transformed data and a checksum associated with the transformed data to provide a propagation signal, and transmitting the propagation signal into drilling fluid or a geological formation. Reception may comprise receiving the propagation signal, demodulating the propagation signal to extract the transformed data and the checksum, and transforming the transformed data into an estimate of the acquired data, using the transform defined by the seed value validated by the checksum. Additional apparatus, systems, and methods are described.

A downlinking signal is transmitted downhole from the surface using drilling fluid as the communications medium. The downlinking signal includes at least a synchronization phase and a command phase. Attributes of the synchronization phase are used upon reception of the signal to determine corresponding attributes of the command phase. Commands may be transmitted downhole while drilling and simultaneously while using mud-pulse telemetry uplinking techniques.

An unstructured grid model with actual well trajectory of individual multilateral wells of a subsurface reservoir is formed. Well trajectory data obtained during drilling of the wells and corresponding to well trajectory data stored as a structured grid model is provided as an input data set for unstructured grid simulation. The unstructured grid model may be formed in a computerized mainframe processor system, or by parallel reservoir simulation by processor nodes of a multicore processor of parallel processor nodes synchronized and under control of a master node.

A method and apparatus that includes positioning a completion string that has an internal passageway and that has an external surface that at least partially defines an external region within a wellbore; isolating a zone of the external region from a wellbore hydrostatic pressure; measuring a pressure within the external region of the isolated zone; determining whether the pressure within the external region of the isolated zone is within a predetermined pressure range; and operating a valve that controls a flow of a fluid through a flow path from the internal region to the external region of the isolated zone when the pressure within the external region is outside of the predetermined pressure range.

A control valve assembly includes a body having a first mud flow passage defining a mud flow inlet and one or more second mud flow passage portions. A magnetic plunger is slidingly mounted within the body. The magnetic plunger includes one or more third mud flow passage portions each including an inlet section and an outlet section configured to selectively align with the one or more second mud flow passage portions. A solenoid is mounted at the body. The solenoid is selectively activated to shift the magnetic plunger between a first position wherein the third mud flow passage portion is misaligned with the one or more second mudflow passage portions and a second position wherein the third mud flow passage portion aligns with the one or more second mud flow passage portions allowing a pulse of mud to flow through the mud flow passage.

A control valve assembly includes a body including a mud flow passage having a mud flow inlet and a mud flow outlet, a magnetic plunger slidingly mounted within the body, and a solenoid mounted at the body about the magnetic plunger. The solenoid is selectively activated to shift the magnetic plunger between a first position covering the mud flow outlet and a second position exposing the mud flow outlet allowing a pulse of mud to flow through the mud flow passage.

A downhole valve is described. The downhole valve has a pilot valve section and a tool section. The pilot valve section has a first tube. The tool section has a second tube slidably coupled to the first tube of the pilot valve section so as to provide fluid communication between the pilot valve section and the tool section. The tool section can be in the form of a signal valve section of a mud pulse telemetry valve, a reamer, a vertical steerable tool, a rotary steerable tool, a by-pass valve, a packer, a whipstock, or stabilizer.

A downhole valve is described. The downhole valve has a pilot valve section and a tool section. The pilot valve section has a first tube. The tool section has a second tube slidably coupled to the first tube of the pilot valve section so as to provide fluid communication between the pilot valve section and the tool section. The tool section can be in the form of a signal valve section of a mud pulse telemetry valve, a reamer, a vertical steerable tool, a rotary steerable tool, a by-pass valve, a packer, a whipstock, or stabilizer.

A wellbore trajectory survey includes an ordered plurality of survey points, each of which has a measured depth, an inclination, and a geographic location. The wellbore trajectory survey is ordered on measured depth. A minimum lateral measured depth (min_LMD) as a measured depth of a first point in the ordered plurality of survey points for which the inclination exceeds an inclination threshold angle is identified. A maximum lateral measured depth (max_LMD) as a measured depth of a last point in the ordered plurality of survey points for which the inclination exceeds the inclination threshold angle is identified. The processor determines from the wellbore trajectory survey that the wellbore at measured depths between the min_LMD and the max_LMD exhibits porpoising into and out of a formation.

A flow-off telemetry system and method of communicating information from a downhole location in a borehole to a surface location while fluid circulation is off. A string is conveyed in the wellbore to define an inner bore and an annulus. During a flow-off condition, an inner bore sealing element closes the inner bore to create a first standing column of fluid in the inner bore, and an annulus sealing element closes the annulus to form a second standing column of fluid in the annulus. A bypass valve in the string at a downhole location between the first standing column of fluid and the second standing column of fluid is activated to generate a pressure pulse including information for performing an action. The pressure pulse is received at a pressure sensor at the surface location and a controller performs an action in response to the information in the pressure pulse.