Print this pageClassification and Assessment of Tight Oil Reservoir in Qingxi Region of Jiuquan Basin
Hexin Huang1,2, Zhenxue Jiang1,2, Qun Luo1,2, Baiying Li1,2, and Wu Fan3
1State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, China
2Unconventional Nature Gas Institute, China University of Petroleum, Beijing, China
3NYU Midtown Center, New York City, NY, USA
As the next step of China's energy hot spot, tight oil has a pivotal position. Currently the development of tight oil has made significant achievements, for instance, Yanchang Formation in Ordos Basin, Fengcheng Formation in Junggar Basin, Lucaogou Formation in Jimusaer Sag, Pingdiquan Formation in Shazhang - Shishugou Sag, Fuyu oil strata of Songliao Basin and Qingshankou Formation, Es1 Member of dolomite and Es3 Member of argillaceous dolomite in Qikou Sag of Bohai Bay Basin, Shuixigou Group in south slope of Qiudong intervale of Tuha Basin, the favorable exploration area is greater than 15 x 104 km2, nearly 7.5 x 108 t reservoir scale, and the resource potential is tremendous.
Through the literature research and practical work, the exploration and development of tight oil should be summarized as following: 1, use hydrocarbon source rock as guidance: as the source of gas and oil, hydrocarbon source rock plays a decisive role for the source storage and proximal enrichment of tight oil; 2 ,use source within and adjacent to the porosity of the hydrocarbon source rocks and fracture development as purpose: hydrocarbon source rock is generally mudstone, large area of tight reservoir space can effectively make up for the lack of oil and gas enrichment in abundance; 3, use optimal source reservoir combination as " dessert " area: select the possible blocks consist of 50% or more hydrocarbon source rocks and reservoir type and interbed reservoir and hydrocarbon source rock strata type, eventually determine the advantageous area conducive to production.
Combining with Junggar Basin saline lacustrine rocks tight oil maturity assessment of dolomite and on the basis of classification evaluation of tight oil in Changqing oilfield, the classification and evaluation of dolomite tight oil reservoir in Xiagou Formation QingXi Region of Jiuquan Basin have been generated. Since QingXi Region Xiagou Formation is mainly composed of argillaceous dolomite and dolomitic mudstone in which organic matter generates hydrocarbon in large area with moderate maturity, it provides a possibility of tight oil storage. Plus the target area has experienced the early cretaceous, late cretaceous and Cenozoic three phase fault superimposed and been deformed by extrusion as well as smaller slip faults development, thus led to the optimization of fracture development in the interval. Large amounts of data processing, deep - shallow resistivity logging curve, natural gamma logging curves and the lithology logging information overall, 1. show dolomitic mudstone and mudstone interval from priority selection of logging data; 2. use natural gamma logging curve further optimization at the same time; 3. refer the numerical size of resistivity logging curve to clear the main hydrocarbon source rocks. Then based on deep - shallow resistivity logging curve difference, combining with ∆lgR method of qualitative identification, target strata in the study area of the fracture development period can be found. Furthermore four types of source reservoir combination will be divided on vertical strata in the study area, including the source-above-storage type, storage-above-source type, large section of the hydrocarbon source rocks and interbed reservoir type, reservoir and hydrocarbon source rock strata type, with large section of the spatial distribution of hydrocarbon source rocks as the instruction, three main source reservoir zone have been found, located in K1g31, K1g13 and K1g03 that thickness of K1g31 combination is significantly greater than the latter two.
Through predecessors' physical experiment and geological understanding, and compared with the hydrocarbon source rocks that closely combined with reservoir types, the hydrocarbon source rocks in the middle of the rock type is thought to be better able to enrich tight oil. Large section of the hydrocarbon source rocks and interbed reservoir type, reservoir and hydrocarbon source rock strata type can be identified as optimal reservoir combination of tight oil which exists in Xiagou Formation generation depression within central and near the fracture development period.
AAPG Datapages/Search and Discovery Article #90180©AAPG/SEPM/China University of Petroleum/PetroChina-RIPED Joint Research Conference, Beijing, China, September 23-28, 2013