ABSTRACT: A Three-Dimensional Reflection Seismic Survey Over the Dollarhide Field, Andrews County, Texas

REBLIN, MICHAEL T., and GREGORY G. CHAPEL, Unocal, Houston, TX, and CHUCK KELLER and STEVEN L. ROCHE, HGS, Houston, TX

A three-dimensional seismic survey over the Dollarhide field, Andrews County, Texas, was collected and analyzed during August 1988 through December 1989. Discovered in 1945, the field is described as a large faulted anticline. This presentation describes the design, pre-planning, acquisition, and processing of this survey and the preliminary results of the interpretation.

The primary geophysical purpose of the survey was to accurately image the location of the faulting within the Dollarhide field to aid in the future planning of enhanced recovery methods.

To design the three-dimensional survey, information including depth, velocity, maximum dip, and reflection data quality are compiled. A subsurface bin size of 110 ft inline by 110 ft crossline was determined to sample adequately the subsurface for processing through three-dimensional migration.

Two innovations reduce the costs of the survey: wide line sampling and simultaneous sweeping. The wide spacing of the source and received lines result in fewer swaths to collect and less surface access costs. In data processing, the data volume is interpolated to a

finer sampling prior to three-dimensional migration.

The second cost reduction technique uses two sets of vibrator sources, simultaneously sweeping. The source separation is accomplished by upsweep-downsweep and phase rotation-summing, giving greater than 40 db of signal separation.

Conventional data processing techniques are applied to the data volume plus three-dimensional DMO. Three-dimensional migration then produces the data volume for interpretation on a workstation.

The interpretation of the three-dimensional data volume yields the following observations. (1) Cross-faulting is more extensive than geological mapped with 40-ac spacing, which directly impacts the tertiary recovery program. (2) A detailed Devonian structure map has pinpointed at least five new well locations in the Devonian unit.

AAPG Search and Discovery Article #91018©1992 AAPG Southwest Section Meeting, Midland, Texas, April 21-24, 1992 (2009)