Study of Carbonate Cement in Lower Cherry Canyon Formation, East Ford, Geraldine Ford and Marsh South Fields, Delaware Basin, West Texas

Saswati Chakraborty and Robert Trentham
The University of Texas of the Permian Basin

The Cherry Canyon Formation of the Delaware Mountain Group is composed of very fine grained, well sorted subarkosic sandstone, siltstones, and mudstone along with argillaceous and organic materials and carbonate cement. These were deposited as part of a succession of slope and basin fan complexes in the Delaware Basin in West Texas and Southeastern New Mexico. Carbonate cement is found to be distributed throughout this reservoir in the East Ford, Geraldine, and Marsh South fields along the Reeves-Culberson County line. Approximately 750ft of core from four wells in these fields spanning 15 miles along the depositional axis have been characterized using petrographic analysis and log studies.

Non-uniform, isolated carbonate cement (0 – 28% by volume) is present in this reservoir. Different types of cemented zones have been identified: (1) blocky isolated concretions, (2) oval or spherical discrete bodies, associated with apparent displacement drape; and (3) spike-like cemented layers with abrupt terminations. Irregular and unpredictable concretions are observed in random with respect to the position (top, middle or base) of beds. Due to the very fine grain size, the volume of carbonate cements seems to be the dominant control on porosity and permeability. Porosity varies significantly (1 to 24%) with the presence of carbonate cements resulting in reduced permeability due to lack of interconnected intergranular porosity.

Interpretation of the distribution and source of these carbonate cemented, non-reservoir intervals are necessary for reservoir characterization. Furthermore, the diversity and distribution of carbonate concretions could indicate of several processes and important variables in these reservoirs.

AAPG Search and Discover Article #90087 © 2008 AAPG/SEG Student Expo, Houston, Texas