Progress and development direction of technologies for deep marine carbonate gas reservoirs in the Sichuan Basin

Abstract

In recent years, deep marine carbonate gas reservoirs have become an important field in increasing conventional gas reserves and production in the Sichuan Basin. Due to complex hydrocarbon accumulation conditions, great burial depth and complicate gas–water relation, however, this type of gas reservoirs faces huge challenges to realize efficient development. In this paper, the development history of deep marine carbonate gas reservoirs in the Sichuan Basin was analyzed. Then, based on such development characteristics and practices, special technologies were summarized. Finally, the research direction for the coming years was pointed out. And the following research results were obtained. First, the reserves of the deep marine carbonate gas reservoirs in the Sichuan Basin vary greatly in scales and types. The reservoirs are of poor quality and strong heterogeneity with active edge and bottom water. The raw gas generally contains acidic gas. What's more, most development wells are located in mountainous areas, and drilled formations are complicated in vertical distribution. Second, special technologies have been formed in the Sichuan Basin, including the fine description technology for strong-heterogeneity gas reservoirs in deep low-gentle structures, the optimized water control technology for the water-bearing gas reservoirs with developed small-scale fractures and vugs, drilling, completion and stimulation engineering technologies for deep complex gas wells, and the support technology for clean and safe development of sulfur-bearing gas reservoirs, so as to provide support for the efficient productivity construction and optimized development of giant marine carbonate reservoirs in the Sichuan Basin. Third, as the development of the carbonate gas reservoirs in the Sichuan Basin begins to convert into the gas reservoirs in ultra-deep complex structures, the next direction of technological research is the fine structure description and thin reservoir prediction technique, across-scale numerical simulation technique, drilling and completion and gas production engineering technique for deep marine carbonate gas reservoirs. It is concluded that these special technologies for the efficient development of deep marine carbonate gas reservoirs provides powerful support for PetroChina Southwest Company to build up giant gas fields with the reserves of tens of billions of cubic meters and realize the leaping growth of gas production. The research results can provide valuable technical reference for the development of deep marine carbonate gas reservoirs at home and abroad.