Abstract: A valve for communication of a measurement while drilling system includes a first structure having a central portion and one or more elongate portions radially extending from the central portion, and a second structure having one or more portions which substantially bound a central orifice region and one or more elongate orifice regions radially extending from the central orifice region. At least one of the first structure and the second structure is configured to be rotated about a rotation axis to produce a relative rotation between the first structure and the second structure such that a flow path through which mud can flow varies as the at least one of the first structure and the second structure rotates about the rotation axis. The central portion has a maximum inscribed circle encircling the rotation axis and having a first radius and the central orifice region has a maximum inscribed circle encircling the rotation axis and having a second radius greater than the first radius.

Abstract: A shock sensing tool for use with well perforating can include a generally tubular structure which is fluid pressure balanced, at least one strain sensor which senses strain in the structure, and a pressure sensor which senses pressure external to the structure. A well system can include a perforating string including multiple perforating guns and at least one shock sensing tool, with the shock sensing tool being interconnected in the perforating string between one of the perforating guns and at least one of: a) another of the perforating guns, and b) a firing head.

Abstract: A valve for communication of a measurement while drilling system includes a first structure having a central portion and one or more elongate portions radially extending from the central portion, and a second structure having one or more portions which substantially bound a central orifice region and one or more elongate orifice regions radially extending from the central orifice region. At least one of the first structure and the second structure is configured to be rotated about a rotation axis to produce a relative rotation between the first structure and the second structure such that a flow path through which mud can flow varies as the at least one of the first structure and the second structure rotates about the rotation axis. The central portion has a maximum inscribed circle encircling the rotation axis and having a first radius and the central orifice region has a maximum inscribed circle encircling the rotation axis and having a second radius greater than the first radius.

Abstract: A shock sensing tool for use with well perforating can include a generally tubular structure which is fluid pressure balanced, at least one strain sensor which senses strain in the structure, and a pressure sensor which senses pressure external to the structure. A well system can include a perforating string including multiple perforating guns and at least one shock sensing tool, with the shock sensing tool being interconnected in the perforating string between one of the perforating guns and at least one of: a) another of the perforating guns, and b) a firing head.

Abstract: An attenuation apparatus, system, and method are disclosed. The attenuator is attached to a pipe and includes a housing that includes an inner sleeve and an outer sleeve. The attenuator includes one or more masses, to resonate when exposed to waves including acoustic frequency components.

Abstract: Various electromagnetic LWD telemetry systems are disclosed having a wireless repeater positioned on or near the seabed. The wireless repeater receives and demodulates electromagnetic uplink signals and retransmits the uplink signals from the seabed as electromagnetic or acoustic signals. A receiver on the drilling platform or suspended from the water's surface receives the uplink signal and forwards it to a facility for processing and storage. In some embodiments, the wireless repeater takes the form of a sub threaded inline with the drill string with an electromagnetic signal sensor positioned inside the drill string. In other embodiments, the wireless repeater takes the form of a unit that rests on the seabed with electromagnetic signal sensors inserted into the sea bottom.

Abstract: A downhole crystal-based clock that is substantially insensitive to the factors that may cause frequency deviation as a result of downhole temperature. The clock may include a plurality of crystals, where a first crystal may be more stable, with respect to temperature, than a second crystal. The crystals may be thermally coupled together so that they may have substantially the same temperature. An error detector may monitor the differences between the frequencies associated with each crystal and provide this information to a storage device. This information may be determined prior to deploying the clock downhole. When deployed downhole, the signal from the error detector may be interpreted in light of the information in the storage device to provide a temperature measurement of the two crystals. The downhole temperature measurement then may be used to reduce frequency deviations in the downhole clock that may result from downhole temperatures.

Abstract: Acoustic telemetry installation in subterranean wells. In a described embodiment, a method of contacting an assembly with a generally tubular string in a subterranean well includes the steps of: suspending the tubular string in the well, the tubular string extending into a surface structure; and then displacing the assembly through the structure into contact with an exterior of the tubular string. The assembly can selectively contact any one of several tubular strings or other objects within a wellhead or casing. The assembly can be permanently or temporarily used on the well.

Abstract: A drill pipe forms an acoustic transmission channel for data to be transmitted from a downhole transceiver to a surface transceiver. By positioning a first low frequency acoustic attenuator between a drill bit and the downhole transceiver, acoustic noise generated by the drill bit is attenuated. Similarly, by positioning the surface transceiver between the top of the drill pipe and a second low frequency acoustic attenuator, acoustic noise generated by surface equipment is attenuated. In this manner, the first and second low frequency acoustic attenuators serve as terminators for the acoustic transmission channel.

Abstract: An acoustic attenuator includes a housing having an inner side surface which defines an interior chamber and at least one dampening member both physically and acoustically coupled to the housing and projecting into the interior chamber. Acoustic energy propagating within the housing is deflected into the dampening members for acoustically dispersal within the interior chamber. In various aspects thereof, the dampening members may include one or a group of two or more generally cylindrical sleeves having one end both physically and acoustically coupled to the housing and a second end projecting into the interior chamber. Preferably, when a group of two or more cylindrical sleeves are employed, the sleeves are nested within one another. The dampening members may further include a second, oppositely disposed, group of two or more acoustic attenuators nested within one another and interdigitated with the first group of cylindrical sleeves.

Abstract: One embodiment includes an apparatus that includes a piezoelectric transducer to generate an acoustic signal that is to modulate along a mandrel, wherein the piezoelectric transducer includes at least one piezoelectric element and at least one electrode that is without non-permanent joints.

Abstract: A system and method for determining blockage in a wellbore containing fluid and/or in a formation adjacent the wellbore, according to which energy is generated in the fluid and variables associated with the energy are measured.

Abstract: An attenuation apparatus, system, and method are disclosed. The attenuator is attached to a pipe and includes a housing that includes an inner sleeve and an outer sleeve. The attenuator includes one or more masses, to resonate when exposed to waves including acoustic frequency components.

Abstract: A downhole crystal-based clock that is substantially insensitive to the factors that may cause frequency deviation as a result of downhole temperature. The clock may include a plurality of crystals, where a first crystal may be more stable, with respect to temperature, than a second crystal. The crystals may be thermally coupled together so that they may have substantially the same temperature. An error detector may monitor the differences between the frequencies associated with each crystal and provide this information to a storage device. This information may be determined prior to deploying the clock downhole. When deployed downhole, the signal from the error detector may be interpreted in light of the information in the storage device to provide a temperature measurement of the two crystals. The downhole temperature measurement then may be used to reduce frequency deviations in the downhole clock that may result from downhole temperatures.

Abstract: Fluid property sensors and associated methods of calibrating sensors in a well provide enhanced well monitoring and control. In one described embodiment, an external venturi flowmeter is utilized to determine a flow rate of fluid from a zone into a tubing string, independent of flow into the tubing string of fluid produced from any upstream zone. In another described embodiment, a gamma ray fluid density sensor utilizes a unique combination of gamma ray sources and detectors to determine a density of fluid flowing through a tubing string. In yet another embodiment, external tubing string sensors are used to determine properties of fluid from a zone into a tubing string, independent of flow into the tubing string of fluid produced from any upstream zone. In still another embodiment, sensor systems for multiple independently produced zones are calibrated.

Abstract: Fluid property sensors and associated methods of calibrating sensors in a well provide enhanced well monitoring and control. In one described embodiment, an external venturi flowmeter is utilized to determine a flow rate of fluid from a zone into a tubing string, independent of flow into the tubing string of fluid produced from any upstream zone. In another described embodiment, a gamma ray fluid density sensor utilizes a unique combination of gamma ray sources and detectors to determine a density of fluid flowing through a tubing string. In yet another embodiment, external tubing string sensors are used to determine properties of fluid from a zone into a tubing string, independent of flow into the tubing string of fluid produced from any upstream zone. In still another embodiment, sensor systems for multiple independently produced zones are calibrated.

Abstract: Fluid property sensors and associated methods of calibrating sensors in a well provide enhanced well monitoring and control. In one described embodiment, an external venturi flowmeter is utilized to determine a flow rate of fluid from a zone into a tubing string, independent of flow into the tubing string of fluid produced from any upstream zone. In another described embodiment, a gamma ray fluid density sensor utilizes a unique combination of gamma ray sources and detectors to determine a density of fluid flowing through a tubing string. In yet another embodiment, external tubing string sensors are used to determine properties of fluid from a zone into a tubing string, independent of flow into the tubing string of fluid produced from any upstream zone. In still another embodiment, sensor systems for multiple independently produced zones are calibrated.

Abstract: Fluid property sensors and associated methods of calibrating sensors in a well provide enhanced well monitoring and control. In one described embodiment, an external venturi flowmeter is utilized to determine a flow rate of fluid from a zone into a tubing string, independent of flow into the tubing string of fluid produced from any upstream zone. In another described embodiment, a gamma ray fluid density sensor utilizes a unique combination of gamma ray sources and detectors to determine a density of fluid flowing through a tubing string. In yet another embodiment, external tubing string sensors are used to determine properties of fluid from a zone into a tubing string, independent of flow into the tubing string of fluid produced from any upstream zone. In still another embodiment, sensor systems for multiple independently produced zones are calibrated.

Abstract: A transducer and a receiver for use in logging-while-drilling operations, having internal pressure adjustment mechanisms to equalize the pressure between the interior of the transducer or receiver, and the well fluids.