Sedimentary Facies And Seismic Reservoir Recognition Of Kepingtage Formation In Shun9Well Block Of Tarim Basin

Shuntuoguole Play (Saddle) is located nearly in central Tarim Basin. It is tectonically depression between the Tabei uplift and Tazhong Uplift and Low Uplift between the Manger Depression and Awati Depression. The Silurian Kepingtage Formation is an important oil and gas exploration target of Tarim basin. Only secondary hydrocarbon reservoirs had been found in the Tazhong and Tanan area in the bituminous sandstone. In Tazhong and Tanan, the Lower Member of the Kepingtage Formation is missing. In Shuntuoguole Shun9well area had been found the primary oil reservoir in the Lower Member of the Kepingtage Formation. There are still some divergences of views as to the era of the reservoir, types of sedimentary facies, distribution of sand bodies and types of traps, which are restricting the pace of exploration.In connection with the problems exiting in the Shuntuoguole Kepingtage Formation, the paper is not only cautious in reference on the results of previous studies and massive collection of existing exploration data, but also comprehensively used the principle and method of sedimentary petrology, Seismic Sedimentology, sequence stratigraphy and petroleum geology,etc. To make research in stratigraphic correlation, sedimentary facies analysis, reservoir characteristics, the seismic reservoir recognition, the controlled factors and analysis of favorable exploration target, which provides scientific basis for later exploration.The main results and insights from the research are as follows:1、Using seismic sequence stratigraphy theory to guide seismic horizon calibration and regional tracking of long seismic lines, in the seismic profile of Shuntuoguole, the new interpretation bottom boundary of Kepingtage Formation (T70) is lower250ms than the original seismic horizon. The sandstone character of the Lower Member of the Kepingtage Formation of Shun9well region is mudstone alternated with sandstone, which is different from all sandstone of outcrop and fine sand or mudstone of Tuopuai area, and is different from pebbled sandstone of Tadong. In Shuntuoguole area, the identification and determine of the Lower Member of the Kepingtage Formation is significant. 2、The stratification of sedimentary facies has been found in cores of the Lower and Upper Member of the Kepingtage Formation. Tidal sedimentary:herringbone cross bedding. Tidal-flat sedimentary:tidal channel sand, wavy bedding, flaser bedding, lenticular bedding. Supralittoral zone:plant roots and the surface of scour. In the cores of the Upper Member of Kepingtage Formation, a lot of coastal deposition evidences have been found, that are bioturbation, low angle washing bedding and wedge-shaped cross-bedding. In the plan of seismic attributes and sand thickness map of seismic inversion of the Lower Member of Kepingtage Formation, the branching and lobate delta front sub-water channel deposits are identified, and distribution of mouth bar sand. Narrow trumpet-shaped tidal channel sand body and a large area of seats like coastal sand body distribution have been identified in the plan of the Upper Momber of Kepingtage Formation.Comprehensive identified that the Lower Member of Kepingtage Formation of Shunl well3D area is estuarine tidal flat-deltaic sediment, and the Upper3and Upper1Members are the two coastal clip shallow water-tidal flat deposits cycles, with combination of sandstone color, texture maturity, sand body scale, mudstone combination of style and other information.3、In the casting thin sections and electron micrographs have found two times cementation of calcite, one time of secondary quartz overgrowth, two times dissolution of siliceous particles and one time of calcite dissolution (iron) dolomitization. It is also difference of illite smectite mixed layer of kaolinite in the plane. Multi-metal oxide crystals that may be corundum have been identified, which may reflect the Permian hydrothermal origin. It can conjecture that the lower Kepingtage Formation sandstone sporadic bituminous may be associated with hydrothermal, and the crude bituminization sandstone of the upper Kepingtage Formation is possibly caused by supergene oxidation.4、Comprehensive analysis of the trap types and reservoir control factors believe that the main reservoir types of the Shun9well of Lower Member of Kepingtage Formation are lithological-structural composite reservoir and Delta sandstone lithologic reservoir. Types of the Upper Member of Kepingtage Formation are structural reservoir and Sand lens lithological reservoir of tidal channel. The east part of Shuntuoguole and north part of Tazhong-I fault may be developmental incised valley formed the stratigraphic overlap reservoir of Lower Member of Kepingtage Formation and Lithologic reservoir controled by turbidity current or delta.The innovative points mainly embodies in:①Proving that the reservoir of Shun9well belongs to the Lower Member of the Kepingtage Formation. Through horizon calibration and long distance tracing contras with Tazhong and Tabei areas. A large incised valley of east-west is developing in the north part of Tazhong-Ⅰ fault. Multiple centric eruptions of volcanic rocks are along with the bottom of incised valley. The valley fillings are mainly from Tadong.②The sedimentary center of the Lower Member of the Kepingtage Formation is located in the Area to the South of the TP2well and the North of the TZ33well.The incised valley is filled up nearly completely after deposition of the Lower Member of Kepingtage Formation and the reservoir that is found currently belongs to the Lower Member of Kepingtage Formation. The classic masses of the Lower Member of the kepingtage Formation mainly came from the northern margin of the basin and crossed the center of the incised valley formed the delta front sand body. The Tazhong Uplifted region did not supply sediments to the Shun9well area. The Lower Member of Kepingtage Formation up thinning out at the top of the south area of the Tazhong I faults.