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GEOREF RECORD

Dipmeter analysis by a Monte Carlo technique

W. A. Scheider and W. W. Whitman
Dipmeter analysis by a Monte Carlo technique
Geophysics (March 1990) 55 (3): 320-326

Abstract

The dipmeter is a borehole tool that can be used to estimate the dip direction and magnitude of subsurface bedding. Typical computer dipmeter analysis utilizes crosscorrelation techniques which can be subject to cycle skipping. A Monte Carlo approach, based upon a method that was successfully applied to determining seismic residual statics, has been developed as an alternative dipmeter analysis method.The technique, which can process either raw or derivative dipmeter data, searches for the best-fit plane through a depth interval of the data. This plane would approximate a bedding interface intersecting the borehole. Operating on a parameterized forward model, this statistical, iterative algorithm randomly perturbs a local depth shift applied to a dipmeter trace. The algorithm then checks how well that perturbation fits the data by locally stacking the data interval. Random perturbations that improve the solution are always accepted as updates of the parameters. However, random perturbations that degrade the solution are not necessarily rejected. Occasionally, these bad guesses are retained, which gives the algorithm the ability to avoid converging to local minima.Setting the proper initial acceptance-to-rejection ratio for bad guesses is important for successful convergence. This ratio is initially large but, after many iterations, is decreased substantially. If this ratio is initially too high, convergence may not occur within reasonable CPU time. If the ratio is initially too low, convergence to a local minimum may result. Testing showed that only a narrow range of initial bad-guess acceptance-to-rejection ratios led to efficient global optimization.For synthetic and real dipmeter data, better results were achieved when processing differentiated dipmeter data than when processing raw dipmeter data.


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 55
Serial Issue: 3
Title: Dipmeter analysis by a Monte Carlo technique
Affiliation: Colo. Sch. Mines, Dep. Geophys., Golden, CO, United States
Pages: 320-326
Published: 199003
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 6
Accession Number: 1990-011618
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 1990
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