A Higher Resolution Stratigraphic and Sedimentological Study of the Subsurface Queen City Formation (Eocene), Nacogdoches and Angelina Counties, Texas: ABSTRACT

Abstract

The Eocene Queen City Formation is a regressive fluvial-deltaic and shallow-marine depositional unit in the East Texas basin. Subsurface core and electric well log data are being used in a detailed subsurface stratigraphic study of the Queen City Formation in a portion of East Texas. Log data from approximately 250 wells across a seven county area of east Texas were used to produce stratigraphic cross sections plus structure, formation, and net sands isopach maps showing the regional structure and distribution of Queen City facies. Structure contour maps on the Formation top and base indicate progradation onto a gently sloping, structurally uniform shelf. Formation and net sand isopach maps reveal two lobate centers, of deposition extending basinward along southeast-trending depositional axes in Houston, Trinity, and Angelina Counties. These maps also indicate interval thicknesses greater than 200 feet in southwest Houston and Trinity Counties but thinning dramatically to the east and downdip to the southeast. Net sand thicknesses vary from greater than 100 ft proximal to the Formation thicks to less than 10 ft in the more distal areas. Cores from producing fields in Angelina and Nacogdoches Counties are being used in a study of the sedimentology and depositional history of subsurfacemore » Queen City Facies. Previous studies were primarily based on well log data sets alone. Core studies indicate the Queen City Formation in this area is a dominantly fine-grained interval comprised of mudstones, siltstones, and very fine sandstones. Very thin (< 2 ft) sandstones and siltstones are generally located in the uppermost Queen City interval and are attractive shallow production targets.« less