JONES, AL, and JOHN T. PALMER, Palmer Petroleum, Inc., Shreveport, LA

ABSTRACT: Aventura Ranch Field: A Classic Stratigraphic Trap: James Lime, Van Zandt County, Texas

Aventura Ranch field, found September 10, 1990, is the most recent significant James Lime discovery in the East Texas basin. Current estimates indicate recoverable reserves of 20 bcf of gas and 1.5 million bbl of condensate. The field represents a classic stratigraphic trap, formed by a facies change from downdip porous and permeable grainstones, terminating updip into carbonate mudstones, wackestones, and unrelated grainstones.

The James Lime formation consists of poorly sorted, low-porosity lime wackestone/mudstones, and well-sorted reservoir lime grainstones. The reservoir consists of two facies: (1) skeletal grainstones, and (2) oolitic grainstones. The skeletal grainstones are interpreted as deposits adjacent to the James Lime reef core. The oolitic grainstones were deposited as high-energy shoals or bars in shallow, agitated water, possibly paralleling the skeletal grainstones adjacent to the reef. Both interparticle and intraparticle porosity are present in the grainstone facies. Microporosity also is evident and is responsible for suppressing most of the induction log resistivity throughout the field. Resistivity as low as 1.5 ohms is found to be hydrocarbon productive.

Subsequent to the development of the Fairway field, a large James Lime stratigraphic trap had been sought for many years, resulting in only the minor discovery of North Athens field. Several dry holes had been drilled amazingly close to the currently productive area. Perseverance and persistence finally paid off with the discovery of Aventura Ranch field. Currently, the field is producing 6 million cu ft of gas and 425 bbl of condensate a day.

AAPG Search and Discovery Article #90989©1993 GCAGS and Gulf Coast SEPM 43rd Annual Meeting, Shreveport, Louisiana, October 20-22, 1993.