Study On Reservoir Characteristics Of Silurian Tuishubrak Formation In Kongquehe Slope, Tarim Basin

As a ramp-transition zone with northeast higher than southwest area, Kongquehe slope is located in Northeastern part of Tarim Basin between Kuruktag uplift and Manjiaer sag. However, the reservoir of tight sandstone has a good gas-show in Tushibulage Formation Silurian Kongquehe slope area; effected by long-term tectonic evolution and multi-period tectonic superposition, the geological conditions is complex, the quality seismic data in Silurian is low and the reservoir is hard to explore. Previous studies mainly focused on oil and gas accumulation, the research of reservoir is weak. This study based on the research of sedimentary facies, reservoir characteristics, diagenesis, evolutionary sequence, etc. of Tushibulage Formation in Silurian Kongquehe slope Tarim Basin, classify and evaluate the tight sandstone reservoir of Tushibulage Formation and analysis the main controlling factors of high-quality reservoir development by deposition and diagenesis.The Tushibulage Formation Silurian Kongquehe slope is the coarse grain sandstone braided river deltaic deposit develop in none-barrier coast sedimentary system which mainly developed sedimentary microfacies such as braided distributary channel, braided bar sand, underwater distributary channel, debouch bar, underwater interdistributary Bay, etc. Lithology is mainly lithic sandstone, maturity of composition is moderate-poor, maturity of structure is moderate-fine. Diagenesis type is mainly compaction, cementation, dissolution and cataclasis-tectonism, diagenetic evolution affected by tectonic uplift and denudation is not high. Since the Jurassic, diagenesis type has entered mid-diagenetic stage A.The reservoir of Tushibulage Formation Silurian Kongquehe slope is conform to China Petrochemical Corporation (SINOPEC) reservoir standard type Ⅳ-Ⅴ; ultra-low porosity and ultra-low permeability--ultra-low porosity and super-low permeability tight sandstone reservoir, reservoir type is mainly porosity reservoir, porosity-fractured reservoir. The porosity and permeability has obvious positive correlation, but under the influence of micro crack is bigger, correlation is not good. Pore type is mainly dissolution pore, secondly is primary intergranular pore and micro-fracture; the pore structural characteristics is mainly thin-porosity and thin-throat--micro-porosity and micro-throat; the pore-throat connectivity is poor. According to sedimentary microfacies, physical properties and the corresponding relation of electrical, reservoir classification evaluation standards have been established, will the tight sandstone reservoir of Tushibulage Formation Silurian Kongquehe slope is divided into three types.The nature of the parent rock determines the basic characteristics of low porosity and low permeability of The reservoir of Tushibulage Formation Silurian Kongquehe slope. Then the sedimentary differentiation effects reformed the reservoir initially and reflected by different types of sedimentary microfacies. Sedimentary differentiation also effects the late diagenetic transformation.The constructive diagenesis on reservoir that has relatively well original physical property is much more intense. Overall, the sedimentary microfacies with coarser granularity has better reserving property. Sedimentary microfacies are the main controlling factors on the reservoir of Tushibulage Formation Silurian Kongquehe slope. Currently limited to the quality of seismic reflection data, it is difficult to predict reservoir in the transverse section, but with the development of seismic resolution3D seismic and the improvement of seismic resolution, it will be possible to accurately predict reservoir.