RIO GRANDE EMBAYMENT OF GULF COAST BASIN

AEROMAGNETIC SURVEY

PRJ has reprocessed an aeromagnetic survey for the Rio Grande Embayment area of the Gulf Coast Basin. The survey was acquired in 1985 and 1986 by Airmag Surveys, Inc. of Philadelphia, PA. This area has been the focus of continued exploration and production with primary targets being the Frio, Vicksburg, Jackson, Yegua and Wilcox. There are 15 major oil fields in this southern Texas region which spans 12 counties and encompasses more than 30,000 miles. To the west in Webb County are Mirando City and O'Hern fields, the latter of which straddles the Webb/Duvall county line. Moving northeastward in the western portion of Duvall County are Hoffman and Government Wells fields. To the south in Jim Hogg County are Colorado, Prado and Kelsey fields, the latter of which is also contained in Brooks County. Continuing south in Starr County are Sun, Rincon and Garcia fields. To the east in Willacy County are Willamar and Willamar West fields. The north-central portion of this survey covers Tijerina-Canales-Blucher and Seeligson fields which straddle Kleberg and Jim Wells counties. Farther north is Stratton Field on the Kleberg/Nueces County border. This closely-spaced survey is an excellent aid in defining near-surface anomalies here as well as structural features, faulting and regional trends in this area of ongoing exploration and production.

SPECIFICATIONS

Survey size: 33,043 line miles

Line spacing: ½-mile

Line direction: East-west

Tie lines: 1½-mile, north-south in the western portion including all or portions of Webb, Zapata, Starr, Jim Hogg and Duvall counties

5 miles, north-south in all or portions of Kleberg, Kenedy, Willacy, Cameron, Hidalgo, Brooks and Jim Wells counties

Elevation: Low level

Instrumentation: High-sensitivity, optically-pumped Cesium Vapor Magnetometer with 0.25 second sampling

DELIVERABLES

Maps, on reproducible, stable-base mylar at 1 in = 4,000 ft.

• Flight line location
• Total Magnetic Intensity (IGRF-removed) (TMI)

Digital Data

• Profile data containing all relevant data traces
• Grids of TMI

OPTIONAL DELIVERABLES

• Reduced-To-Pole TMI (RTP)
• Vertical Gradient of RTP
• Shaded Relief maps with varying sun angles
• Profiles, on paper

GRAVITY DATA

Gravity data coverage is excellent in nine of the twelve counties within the Rio Grande Embayment area. Coverage is scant in southern Jim Wells County and minimal in Kleberg and Kenedy counties. A total of 34,569 gravity stations are contained in the survey area.

BASIC DELIVERABLES

Maps

• Bouguer gravity with station locations
• Residual gravity (if no interpretive work provided)

Digital Data

• Gravity data on CD-ROM or diskette

OPTIONAL DELIVERABLES

PRJ can provide clients with a variety of interpretive mapping-type tools and integrate the gravity with the magnetic data for a combined interpretation tool. Types of products available include:

• Shaded Relief images of the horizontal gradient representing different sun angles
• Structure maps
• Isopach maps
• Residual gravity map
• 2½-Dimensional gravity and magnetic models