Drilling and Excavation Technologies for the Future (1994) / Chapter Skim
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6. Sensing Systems
6. Sensing Systems
Pages 87-100
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From page 87... ...
These measurements are commonly made 30 to 50 ft behind the drill bit in special sections of the drill pipe. The data are analyzed by downhole computers, and because the drill pipe sections do not form a usable continuous electrical circuit, the final results are transmitted to the surface by pressure pulses in the mud column.
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From page 88... ...
Different types of measurements may be made by using sondes (i.e., instrument packages) suspended on a wireline cable after the drill string has been removed (Figure 6.1~.
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From page 89... ...
The scattering of neutrons or highenergy gamma rays from a source to a detector depends primarily on the porosity and secondarily on the rock type, and sondes have been constructed based on both properties.
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From page 90... ...
status of the Field In what follows He major components and principal problem areas of sensing systems are considered. The major components are bit-rock interaction; formation evaluation and fracture detection at and ahead of the bit; measurement of stress, rock strength, and pore pressure; drill piperock interaction; position, direction, and steering analysis; cutting and mud analysis; environmental logging; telemetry; and data analysis, measurement interpretation, and activation systems.
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From page 91... ...
Information about the formations encountered uphole is recorded and transmitted with He drill string in place hours after drilling. Current MWD systems enable sophisticated formation evaluation a few meters behind the current bit location by measuring a wide array of formation properties including resistivity, natural gamma-ray activity, bulk density, and neutron porosity.
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From page 92... ...
Stress, Rock Strength, and Pore Pressure Stress, rock strength, and pore pressure help determine the degree of difficulty that a given bit at a given drilling state will encounter. These formation attributes are also key in the detection of overpressuring and possible blowout risks.
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From page 93... ...
Horizontal and directional drilling requires accuracy in the determination of bit location and in visualization of the drilling direction In three dimensions. Although some sensing systems exist in this domain (Gaudio and Beasley, 1991; Stephenson and Wilson, 1992; Tarr and others, 1992)
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From page 94... ...
Sensing systems that monitor mud composition and rheological properties downhole, as well as at the surface, could lead to intelligent decisions about remedial mud modification and thus to more efficient drilling. Environmental Logging A new area of drilling advancement concerns logging in wells that are drilled for environmental evaluation or remediation.
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From page 95... ...
This slow transmission rate is currently a major limitation and will become a greater liability as more measurements are made in future drilling systems. Data Analysis and Activation Systems Measurements made downhole or in tunneling, mining, and environmental systems require action by the driller.
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From page 96... ...
This would alleviate He need for increased data transmission to an uphole operator. Priorities for R&D R&D is needed to produce advanced, intelligent drilling systems that incorporate advanced sensors and microprocessors.
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From page 97... ...
me development of novel direct sensing of stress, rock strength, and pore pressure for optimizing drilling parameters, steering, minimizing formation damage, and formation evaluation; and (b) He development of technologies to predict pore pressure from acoustic measurements.
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From page 98... ...
activation systems: Downhole data analysis and activation systems may improve overall drilling operations by reducing the need for data transmission uphole for operator decision making. Longterm research is recommended to develop sophisticated software for downhole analysis of drilling data.
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From page 99... ...
T., and Tayler, P J., 1992, Optimal applications engineering and borehole stability analysis avoid differential sticking and lead to successful open hole completion of North Sea horizontal well: Proceedings SPE Annual Technical Conference, Washington, D.C., Oct.
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From page 100... ...
Wraight, P., Evans, M., Marienbach, E., Rhein-Knudsen, E., and Best, D., 1989, Combination format in density and neutron porosity measurements while drilling: Society of Professional Well Log Analysts 30~ Annual Logging Symposium Proceedings, p.
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