Abstract

The Kurten Field, Brazos County, Texas was discovered in August 1976 with the completion of the Bonanza Prodeco Schram #1 at a plugged back depth of 2 530 m (8,300 ft). Oil is produced from five separate Woodbine - Eagle Ford sands of Upper Cretaceous age which occur in a contiguous area exceeding 260 km² (100 sq. mi.) in Brazos, Grimes and Madison Counties. These sands, having a maximum aggregate thickness exceeding 40 m (130 ft.), could ultimately yield in excess of 16 × 10⁶m³ (100 million barrels) of light gravity crude and 2.8 × 10⁹m³ (100 billion cubic feet) of natural gas.

A study of the regional framework of Woodbine - Eagle Ford deposition within the East Texas Basin indicates the five producing sands are probably correlative with a thick mass of sand lying farther east known as the Harris Sand. Isopach maps of the producing sands reveal them to be generally elongate and elliptical with their original geometry partially masked by progressive truncation to the south as the result of post Eagle Ford erosion. Vertical variations in textures, sedimentary structures, and trace fossils indicate that these marine sands were laid down in a shallow subtidal environment. It is suggested that they were deposited as offshore bars related to the marine-dominated “Harris” Delta. Diagenesis occurred in three stages and played a significant role in modifying the composition of the sands and their producing characteristics.

Prior to December 1978, some 100 wells had been drilled with the field limits still undefined. Daily production exceeded 795 m³ (5 000 barrels) oil per day and 5 600 m³ (2.0 MMcf) gas per day. The majority of the wells required sand fracturing and pumps were installed during the first year of production. A pilot water flood will be implemented in 1979 which should ultimately allow a better assessment of potentially recoverable reserves.