Abstract: Aspects of the subject matter described herein relate to creating and validating cryptographically secured documents. In aspects, documents are encrypted to protect them from unauthorized access. An entity having namespace ownership rights may create a document in an authorized namespace and sign the document with a private key. Other entities may validate that the document was created by an authorized namespace owner by using a public key available in security data associated with a parent document of the document. For a root document, the public key may be available from a directory service. A namespace owner may change the namespace owner(s) that are allowed to create children of a document.

Abstract: Methods and apparatus for acquiring acceleration waveform measurements while deploying a tool along a borehole. A conveyance and a sensor section are configured to deploy the sensor section in the borehole. At least one multi-axis receiver is configured to detect acceleration waveform signals while the sensor section is being deployed in the borehole.

Abstract: Computers are provided with a totally ordered, durable shared log. Shared storage is used and can be directly accessed by the computers over a network. Append-log operations are made atomic in the face of failures by committing provisional append ordering information onto a log. The log may comprise multiple flash packages or non-volatile memory devices, referred to as segments, although any shared storage device(s) may be used. Each log record is a multi-page stripe, where each page of a stripe is written to a different segment. Fault-tolerant protocol variants append stripes to the log, such that stripes are totally ordered in the log and each stripe is written atomically.

Abstract: A fiber optic distributed vibration system for detecting seismic signals in an earth formation is provided. The system includes a fiber optic cable deployed in a borehole that extends into the earth formation and which is configured to react along its length to a seismic wave incident on the fiber optic cable from outside the borehole. An optical source launches an optical signal into the fiber optic cable while the seismic wave is incident thereon. A receiver detects coherent Rayleigh noise (CRN) produced in response to the optical signal. A processing circuit processes the detected CRN signal to determine characteristics of the earth formation.

Abstract: A fiber optic distributed vibration system for detecting seismic signals in an earth formation is provided. The system includes a fiber optic cable deployed in a borehole that extends into the earth formation and which is configured to react along its length to a seismic wave incident on the fiber optic cable from outside the borehole. An optical source launches an optical signal into the fiber optic cable while the seismic wave is incident thereon. A receiver detects coherent Rayleigh noise (CRN) produced in response to the optical signal. A processing circuit processes the detected CRN signal to determine characteristics of the earth formation.

Abstract: Methods and apparatus for borehole seismic survey are disclosed comprising a first seismic source under water at a first location and a second seismic source at a second, deeper location. Seismic signals from the seismic sources are recorded with synchronized sensors located in a borehole and source signature data are obtained by combining the recorded seismic signals such that low and high frequency content of the combined source signature data is extended relative to the source signature of the first seismic source and the second seismic source.

Abstract: A technique is designed to measure parameters of hydrophones, such as measurement of hydrophone acceleration canceling properties. The technique involves testing a selected hydrophone under conditions representative of the actual conditions in which the hydrophone is to be operated. By using the representative conditions, the acceleration canceling properties of the hydrophone and/or other parameters of the hydrophone are more accurately determined.

Abstract: A multiple sensor fiber optic sensing system includes an optical fiber having at least first fiber optic sensors and second fiber optic sensors deployed along its length. In response to an interrogating pulse, the first fiber optic sensors generate responses in a first optical spectrum window, and the second fiber optic sensors generate responses in a second, different optical spectrum window. The responses in the first optical spectrum window are measured in a first optical spectrum channel, and the responses in the second optical spectrum window are measure in a second, different optical spectrum channel and provide simultaneous indications of one or more parameters, such as temperature and pressure, in the environment in which the sensors are deployed.

Abstract: Methods and apparatus for facilitating optical communications and sensing, with downhole optical or other sensors, in high temperature oilfield applications. The apparatus can include a downhole telemetry cartridge for downhole use at temperatures in excess of about 115 degrees Celsius. The apparatus can also include a downhole light source optically connected to the telemetry cartridge. The light source may include at least one remotely pumped laser optically connected to a surface pump laser via optical fiber(s). The remotely pumped laser may drive the downhole optical or other sensors for their operations.

Abstract: Aspects of the subject matter described herein relate to cryptographically controlling access to documents. In aspects, documents are encrypted to protect them from unauthorized access. A security principal seeking to access a document first obtains the document. The document includes an identifier that identifies security data associated with the document. The security data includes an encrypted portion that includes authorizations for security principals that have access to the document. A security principal having the appropriate key can decrypt its authorization in the security data to obtain one or more other keys that may be used to access the document. These other keys correspond to access rights that the security principal has with respect to the document.

Abstract: Methods and apparatus for acquiring acceleration waveform measurements while deploying a tool along a borehole. A conveyance and a sensor section are configured to deploy the sensor section in the borehole. At least one multi-axis receiver is configured to detect acceleration waveform signals while the sensor section is being deployed in the borehole.

Abstract: Transactional record management methods and systems enabling multiple independent servers (such as database servers) using shared storage to initiate transactions in parallel without inter server communication and without locking the records used by the transaction. The in-flight transactions can be included in a shared transaction log without a final determination of whether the transaction committed. The log updates can be broadcast to each of the servers, which each parse the log, using the same rules of analysis, and therefore each compute server can independently and asynchronously come to the same conclusion as to which transactions aborted and which transactions committed.

Abstract: A distributed optical acoustic sensor is provided along a structure in a body of water. The distributed optical acoustic sensor is used to detect acoustic waves generated by at least one acoustic source for positioning of at least one object in relation to the structure.

Abstract: Computers are provided with a totally ordered, durable shared log. Shared storage is used and can be directly accessed by the computers over a network. Append-log operations are made atomic in the face of failures by committing provisional append ordering information onto a log. The log may comprise multiple flash packages or non-volatile memory devices, referred to as segments, although any shared storage device(s) may be used. Each log record is a multi-page stripe, where each page of a stripe is written to a different segment. Fault-tolerant protocol variants append stripes to the log, such that stripes are totally ordered in the log and each stripe is written atomically.

Abstract: A fiber optic distributed vibration system for detecting seismic signals in an earth formation is provided. The system includes a fiber optic cable deployed in a borehole that extends into the earth formation and which is configured to react along its length to a seismic wave incident on the fiber optic cable from outside the borehole. An optical source launches an optical signal into the fiber optic cable while the seismic wave is incident thereon. A receiver detects coherent Rayleigh noise (CRN) produced in response to the optical signal. A processing circuit processes the detected CRN signal to determine characteristics of the earth formation.

Abstract: A gas detector (10) that is arranged to sense the concentration levels of target gases oxygen, methane, carbon monoxide, and hydrogen sulphide, within a gas sample from an environment surrounding the detector. The gas detector (10) comprises laser sources (12a-12d) that are arranged to transmit radiation through the gas sample at four target wavelengths that correspond approximately to the optimum absorption wavelengths of each of the target gases and an optical detector (16) that is arranged to sense the intensity of the radiation transmitted through the gas sample at each of the target wavelengths. A control system (22) generates representative concentration level information for the target gases based on the level of absorption of the radiation transmitted.

Abstract: Subterranean oilfield high-temperature devices configured or designed to facilitate downhole monitoring and high data transmission rates with remotely pumped lasers that are configured for operation downhole, within a borehole, at temperatures in excess of 115 degrees Celsius.

Abstract: A system for use in a well includes an optical cable for positioning in the well. An optical sensor is optically coupled to the optical cable, where the optical sensor has a capillary tube and an optical fiber in the capillary tube. The capillary tube also includes a first sealed region containing a metallic material that is in liquid form at a downhole temperature in the well. A joint mechanism may attach the optical sensor to the optical cable.

Abstract: A technique is designed to measure parameters of hydrophones, such as measurement of hydrophone acceleration canceling properties. The technique involves testing a selected hydrophone under conditions representative of the actual conditions in which the hydrophone is to be operated. By using the representative conditions, the acceleration canceling properties of the hydrophone and/or other parameters of the hydrophone are more accurately determined.

Abstract: Single fiber optical telemetry systems and methods are disclosed. The methods and systems facilitate input and output via a single fiber optic interface. The optical telemetry systems and methods also facilitate faster data transmission rates between surface and downhole equipment in oilfield applications.