Distribution Characteristics of Tight Sandstone Gas Reservoirs of Xujiahe Formation in Central Sichuan Basin

Abstract

AbstractIn order to effectively guide the relevant exploration and development of tight gas in Xujiahe Formation in Central Sichuan Basin, in view of the mismatching between the resources and reserves, the mismatching between reserves and production, by utilizing the data of core, outcrop, drilling, well logging, well testing, laboratory analysis and testing, the tight gas reservoir of Xujiahe Formation was studied in the aspects that fine stratigraphic division of well-seismic combination, fine structure interpretation and fine gas reservoir analysis and establishment of the main controlling factors of gas reservoir formation. The results showed that: ①Tight gas reservoirs are developed in the 2nd, 4th and 6th members of Xujiahe Formation, of which the 2nd member (X2) is the largest one in scale. ②Through fine stratigraphic division of the X2, it was found that physical properties of reservoir are different vertically, the porosity of X23 is obviously lower than that of X21+2. By reducing the Effective porosity standard and reinterpreting reservoirs, effective reservoirs thickness of X23 was increased obviously. ③Trough analysis of gas reservoirs, it was found that the types of gas reservoirs in the different sub member are different. In the past, X21 and X22 are the main exploration sub members, they produced gas and water together and had good physical property. Structure is the main controlling factor of the gas reservoir forming, so they belongs to Structural Gas Reservoir; The X23 with poor physical property mainly produces pure gas, whose reservoir is tighter. Physical property is the main controlling factor of X23 gas reservoir forming. The X23 belongs to lithologic gas reservoir. ④Different exploration ideas are adopted for different types of gas reservoirs. For X21+2, favorable targets should be found in newly discovered structures traps. For X23, the sweet spot can be found by predicting reservoir areas with good physical properties, combined with horizontal well and stimulation fracturing measures, a new breakthrough in tight gas exploration is expected. The research results can provide theoretical and technical support for the resource discovery and effective production of Xujiahe tight gas reservoirs in Central Sichuan Basin. KeywordsSichuan BasinXujiahe formationTight gasTypes of gas reservoirsExploration direction