Abstract:
A downhole system comprises a main sensor, such as a gamma sensor, and a backup sensor. The backup sensor may be of a different type from the main sensor. In some embodiments the backup sensor is a high reliability sensor that may have a different sensitivity from the main sensor. The system operates both the main and backup sensors and generates calibration data for the backup sensor. If the main sensor fails the calibration data may be applied to process data from the backup sensor to yield an estimate of the data that the main sensor would have yielded if it had remained operational. The calibration data may compensate for temperature variations and/or temporal drift, for example.
Abstract:
An assembly for use in subsurface drilling includes a downhole probe supported in a drill string section by centralizing features of a centralizer that is slidably removable from the drill string section. The centralizer may comprise a tubular body having a bore defined through it. A bore wall of the centralizer is fluted to provide inward contact points that support the downhole probe. The downhole probe may be supported for substantially its entire length. The centralizer may optionally comprise and/or be coated with a vibration damping and/or electrically insulating material.
Abstract:
An assembly for use in subsurface drilling includes a downhole downhole probe supported by a centralizer. The centralizer comprises a tubular member that extends around the downhole probe. A wall of the centralizer is fluted to provide inward contact points that support the downhole probe and outward contact points that bear against a bore wall of a section of drill string. The downhole probe may be supported for substantially its entire length.
Abstract:
An assembly for use in subsurface drilling includes a downhole probe supported by a locking mechanism with a bore of a drill string section. The probe comprises a first spider and a second spider at the uphole and downhole sections of the probe. The locking mechanism secures the probes in the bore against axial and rotational movement relative the drill string section.
Abstract:
A telemetry method transmits data by MP telemetry to a telemetry relay system which retransmits the data by EM telemetry. The method avoids the need to incorporate MP telemetry pressure transducers into rig equipment and permits telemetry from regions unfavourable for EM telemetry because of depth and/or characteristics surrounding formations.
Abstract:
A jig and method useful for coupling and/or uncoupling drill string sections. In some embodiments, the jig comprises a body having an outer surface for engaging a torqueing tool and a cavity extending from a first end to a second end of the body and an engagement means at the first end of the body. The engagement means may be dimensioned to non-rotationally engage an outer surface of a first end of a drill string section and the cavity may be sized to fit about a drill string section.
Abstract:
An electromagnetic telemetry signal generating assembly comprises a first section of drill string, a second section of drill string, a gap sub configured to insulate the first section from the second section, and a power source configured to provide a first voltage to a control circuit. The control circuit is configured to drive a second voltage between the sections of drill string. The gap sub provides a gap of at least 12 inches (30 cm). The second voltage may be different than the first voltage.
Abstract:
An insulating collar for a gap sub assembly for electromagnetic (EM) telemetry used in downhole drilling is disclosed. The gap sub assembly comprises a female member comprising a female mating section and a male member comprising a male mating section and a gap section. The male mating section is matingly received within the female mating section and electrically isolated therefrom. The insulating collar is positioned on the gap section. The collar is made up of a framework with a plurality of discrete bodies spaced about the framework and a portion of each of the discrete bodies protrudes above the framework. Either the framework or the discrete bodies are made of an electrical insulator material to electrically isolate one end of the collar from the other end of the collar. The collar therefore electrically isolates the male member from the female member and the male member, female member and insulating collar function as the “gap sub” for EM telemetry.
Abstract:
A method for using a downhole probe. The method comprises providing a probe, at least one vertical cross section of the probe having an area of at least pi inches squared. The method further comprises inserting the probe into a bore of a drill collar and passing a drilling fluid through the bore of drill collar at a flow velocity of less than 41 feet per second.