Development techniques of multi-layer tight gas reservoirs in mining rights overlapping blocks: A case study of the Shenmu gas field, Ordos Basin, NW China

Abstract

The difficulties of making joint development of coal and natural gas were examined and the technical countermeasures were given through studying the case of the Shenmu gas field of the Ordos Basin, where the mining rights of coal and natural gas overlap completely. Based on the study of the main controlling factors of the distribution of favorable areas in the Upper and Lower Paleozoic formations, technical measures for different areas were determined considering well type, well pattern, efficient drilling and production, and ground gathering technology. The results show: The mining rights overlapping area of coal and natural gas can be developed jointly. The effective reservoirs of the multi-layer tight gas reservoirs can be divided horizontally into the superposition area for multi-boundaries sand body, multi-layers sand body and isolation sand body in the Upper Paleozoic formations, and the superposition area for effective reservoirs in the Upper and Lower Paleozoic formations. A cluster well group which includes nine wells is the optimal well pattern. Different reservoir area should be developed by different well type and patterns. The construction and development period of gas reservoirs will be shortened by the application of cluster well group, optimized technologies of drilling and production, and ground supporting facilities. Practice shows that the three dimensional development of the multi-layer tight gas reservoirs is also realized in the Upper and Lower Paleozoic when the joint development of coal and natural gas is done in the mining rights overlapping areas. Key words: Shenmu gas field, mineral rights overlapping block, coal bed, tight gas reservoir, collaborative development, well type and pattern, corresponding technology