Study On Reservoir Characteristic Of The JP2 Pool In Majing Gas Field

Majing gas field located at Majing town,which 9km south of Shifang city , Sichuan province. is the south-west branch of Sinopec newly discovered medium gas field in recent years. Regional geological, the Majing structure is in the west of Sichuan basin, northeast the Longmen Mountain center-section predestined affinity Penxian fault sole, is a low scope underlying anticline which NE moves toward. Sedimentary, Majing site is located in the region (fan) delta front - littoral and shallow lake environment in late Jurassic, had experienced the lake transgression ~ greatest lake transgression ~ lake regression period of evolution.The JP2 gas reservoir of Majing gas field belong to under the anticline control elastic seal gas drive gas reservoir, which is the main production area gas reservoir and delivers the high quality natural gas primarily. The gas reservoir have 5 sets of longitudinal sand body ,and composed of JP22, JP23, JP25 for industrial gas. After the past few years a large number of new wells into production,the gas reservoir development has been very good results, output increased significantly. Information from the known, the gas reservoir by a number of gas-bearing sandstone from interlaced overlay. Since there is no system of geological features and characteristics of the distribution of gas and water, so the effective distribution of the characteristics of the reservoir is not clear awareness, which led to the development of gas reservoirs in the follow-up on the lack of specific guidance.According JP2 gas reservoir in Majing gas field is place in the mid-stages of development, seismic, coring, logging, mining and other test data are quite rich; took single-well analysis technical was taken as the breakthrough point, and use other types of information was used flexibablely in the research of characteristics of the gas reservoir. In the study, conventional methods and technical of reservoir description were used mostly to do thin layer division and contrast, sedimentary microfacies and sand body distribution and characteristics of effective sand delineation and distribution and so on. In the technical aspects of mapping, Double Fox and Carbon mapping & data analysis software were used mostly;which are more advanced, higher precision and widely be used at present. In order to improve the mapping accuracy, generally, the Kriging interpolation was used between control points of wells to map. If well datas are absence in some region, study referred to the previous seismic interpretation results, insert the appropriate control point, as far as possible to restore the original chara- cteristics of the reservoir.The study found by: The thickness, distri- buting feature and reservoir quality of sand body are closely related to sedimentary microfacies and ,the favorable sedimentary micro-facies of JP2 gas reservoir are underwater distributary channel and mouth bar. Physical properties of reservoir rock is bad,generally, average porosity of 8.61%, average penetration rate of 0.557×10-3μm2 and average water saturation of 44.7%, belongs to low porosity and low permeability tight sandstone reservoir near. There great difference in effective reservoir thickness and area of distribution of layer and interlayer. Effective reservoir are most distributed in the JP22, JP23, JP25 three sub-paragraph of the west wing and the north-east of the antic- line, good lace. Classification of evaluation in the reservoir: classⅡare the main reservoir;classⅠare mainly distributed in JP22, JP23 construction northeast, was not the sporadic distribution of lace; JP25 mainly belongs to classⅢreservoir,can product industrial gas, but even after fracturing and other measures, the output is still relatively low. The most favorable zone is located in north-eastern part of the anticline , the larger particle size sand, low clay content, best physical properties, many high-yield wells in the region.The more favorable zone is located in west wing of the anticline , reservoir of classⅡmainly, large thickness and area of effective reservoir,is the main production region of JP2 gas reservoir in Majing gas field.During the study process, the dynamic information of development was taken as feedback timely, then,the contradictions between theory and dynamical information of development were made deeper study in, so as to achieve a higher precision accuracy, better understand the characteristics of the reservoir and, ultimately, for work area development of follow-up to provide better guidance, and, proposed the universal use research methods of the reservoir characteristics in mid-development stage of the tight sandstone reservoir near in western Sichuan,so as to enrich the content of this field.