Structural Evaluation And Comprehensive Evaluation Of Traps In The Northwestern Margin Of The Junggar Basin

The 8-466 district is located in the depression of Ke-Wu fault zones in the northwest of Junggar basin. The whole block is a monoclinal structure, which raised in the northwest. The traps are mainly structure-lithology traps and lithology traps. Because of the complex structures and the overlap conditions of sand and shale, the newly discovered traps are not reliable and there is no new exploration discovery. It has the very good practical significance to carry out the fine structure interpretation and the comprehensive evaluation of traps in this area.Based on the fine interpretation and the regional sedimentary characteristics analysis, the sedimentary facies types, the lateral distribution and the sedimentary evolution have been analyzed combined with the geology, core, logging and testing data. At the same time, carried out the fine research on the favorite zones, built the form of structure-lithology reservoirs, predicted the favorable zones of structure-lithology traps and pinched out the favorable target zones. The main reserch results are as follows.Lower Wuerhe Formation can be divided into five small layers:P2w1-1?P2w1-2?P2w1-3? Paw1-4?P2w1-5 from top to bottom in The 8-466 district. They are corresponded to Upper Wuerhe formation, Lower Wuerhe formation, Xiazijie formation, Fengcheng formation. Then clarified the internal layers relationships of Permian and stratigraphy distribution characters.Through the structure oriented filtering processing, the top structures and faults distribution characters of the five internal reflection layers in Wuerhe Formation have been determined combined with the fine structure interpretation by using coherence technique, volumetric curvature technique, horizontal slices technique and layer flattening technique. It has clarified the whole structure characteristics from upper Wuerhe formation to Fengcheng formation and it is a southeast trend monoclinal structure. It mainly developed the Hercynian faults in the study area. The plane distribution is mainly divided into two groups of faults, northeast orientation and southeast orientation. NE faults controlled the structure patterns and sedimentary strata, nearly SE faults are the adjustable strike-slip faults.Based on the facies analysis of single key well and well-tie in study area, lower Wuerhe formation in Permian is a set of alluvial-proluvial fan and fan delta depositional system with clastic rock reservoirs of glutenite and sandstone and it is the tight reservoir with low porosity and super low permeability.Through the techniques of the impedance inversion, emerge inversion and amplitude attribute analysis, the favorable traps have been finely depicted, and 5 traps of the different types have been discovered and implemented.Based on the analysis of the known reservoirs and surrounding remained oil and gas wells, the main controlling factors of hydrocarbon accumulation in the study area is the implementation degree of the traps and the matching relations of oil-source faults, and the reservoir types are mainly fault-lithology reservoirs and lithology reservoirs with tectonic background.Combined with the researches of the structure, reservoirs distribution and the oil and gas accumulation regularities, the distribution of the favorable reservoirs have been predicted. Based on the prediction, the favorable zones and the targets have been evaluated and optimized, and 4 favorable target areas are predicted.