Comprehensive Evaluation Of The Third Segment Of Xujiahe Reservoirin Jiange-yuanba Area

The Jiage-Yuanba area is located in the border region of northeast and northwest Sichuan Basin, the early exploration object mainly for the Jurassic strata, etc,and the Xujiahe formation are not included in the focus. In recent years,the gas testing results of Longgang and Yuanba gas field in continental strata achieve ideal effect,which shows that the continental strata in Sichuan Basin have good exploration and development prospect. Compared with the second section of Xujiahe formation, the fourth section of Xujiahe formation and the sixth section of Xujiahe formation, the third section of Xujiahe formation in study area has the characteristics of poor physical property, strong heterogeneity, high density, gas reservoir complicated and sand shale interbed.Also in the early stage of exploration,there is no detailed understanding about the reservoir distribution and the influence factors of reservoir development. On the basis of drilling cores,scanning electron microscope, casting lamella, Well logging,some relevant test analysis and a series of past research results,we raise awareness of reservoir characteristics. In view the syudy of the sedimentation characteristics, the distribution of sandstone strata,the reservoir characteristics and the reservoir estimate of the third section of Xujiahe formation in study area.On the basis of previous studies, research on the sedimentary microfacies of the Third Segment of Xujiahe reservoir. According to the lithology identification standard, identification of sand body in the studied area, research on the rules of sand body distribution. Through the previous analysis, combined with thin section identification, core observation, core analysis, mercury injection data, etc.,research on the petrological characteristics of reservoir, the reservoir space types, physical characteristics and pore structure characteristics.Combining with the testing data and logging data, identification of gas. According to the testing and test data, classification and evaluation of the test well,and dynamic evaluation of reservoir. Finally, determine the lower limit of reservoir, establishment of comprehensive reservoir classification evaluation standards and evaluation of the reservoir. Through the sedimentary facies research of he third segment of Xujiahe reservoir,realizing that The sedimentary subfacies of the third segment of Xujiahe reservoir in the study area include fan delta plain, fan delta front and littoral and shallow lake, development of braided river distributary channel, underwater distributary channel microfacies,etc.The main rock types of the third segment of Xujiahe reservoir are fine to medium-grained lithic sandstone. Pore types are mainly intergranular dissolved pore, clay complex matrix pore and microfracture.Reservoir porosity is mainly distributed in 1%~3%, the permeability distribution concentrated in 0.01 ~ 0.1×10-3?m2, which is the low porosity, low permeability reservoir.Gas reservoirs are mainly distributed in sand group I, II, III, and widely distribution in the study area, thickness thinning from northwest to southeast direction, compared with the plane distribution of sedimentary microfacies.There are the biggest gas thickness in the area where underwater distributary channel development in northwest area and tectonic position relatively high composited.The reservoir in the study area generally produce gas, no water production,and the production mainly for middle to high yield. According to the test conditions and divided the test well into four categories, analysis of the dynamic characteristics of all kinds of test well.According to the study in reservoir physical parameters, petrological characteristics and thickness of sand body, and combining previous research,establish a comprehensive standard of reservoir classification evaluation,and classify all the wells using the comprehensive standard of reservoir classification evaluation.