| The Ziyang-Dongfengchang field,a favorable zonefor oil and gas accumulation,is Locate in thehigh structural position of the southwestSichuan area.This is a important target field for enhancereserve and productivity of the southwest branch company of Sinopec,and it’s have great potential for oil-gas exploration and development.However,as a new field for exploration and development,it’s lack of system research on engineering geological and deficiency scientific basisfor design and construction.And this is also a serious threat to the goal of safe andefficient productionand enhance reserve and productivity.In addition,some corresponding measures for reservoir reform are used in the XuJiahe Gas Reservoir of Dongfeng 2 well,Dongfeng 3 well and Dongfeng 6 well;but most layer began to produce water after reservoir reform measures,the three Wells have not obtain ideal production effect in the end.The mechanics parameters of rock is the base material of oil drilling,fracturing engineering design,the calculation of tectonic stress field,and the fracture prediction.The crack development and many other problems in oilfield engineering are closely related tothe mechanical properties of the rock. Therefore,the application of the rock mechanics parameters research has important realistic and economic value.In view of the important application value of rock mechanics parameters and the need of the actual situation of exploration and development,this paper adopts the indoor experiment method combination with the logging data analysis method,mainly aimed at the research of the Xujiahe formation of continental strata.On the basis of theregional geological data in this area,we collected conventional logging data,imaging logging data,mud logging data,drilling data,fracturing data of 6 Wells such as Chuan 7 well,Chuanfeng 188 well,Dongfeng 2 Wells,Dongfeng 3 well,Dongfeng 6 Wells and Ziyang 1 well.Through a large number of core experiment,we obtained the rock mechanics parameters,such as rock density,elastic modulus,poisson’s ratio,tensile strength,compressive strength,cohesion and internal friction angle,and we also understood the reservoir sensitivity characteristics. Combining with the logging data, we established the rock mechanics parameter prediction model and the profile of the rock mechanics parameters about this region, and then we analyses the distribution regularity of the rock mechanical parameters. We use the Eaton method as a optimization method to establish formation pressure prediction model and profile about sound wave logging data, density logging data, resistivity logging data,according to the undercompaction theory,and this enabled us to understand the vertical distribution law of the formation pressure of this area. On the basis of above work, we use acoustic emission experiment, differential strain experiment and field data to determine the crustal stress size and orientation,and then build models of continental strata collapse pressure and fracture pressure, using the GMI-Wellcheck module of the GMI geostress modeling software to analyze the borehole wall stability. Above all the study of engineering geological parameters, we discussed the fluid density window for safely drilling,the feasibility of underbalanced drilling,the selection of the perforation azimuth,the optimization of the drill bit type,the forming condition of Joint network,the optimization of fracturing fluid and fracturing technology,etc. Finally,we put forward the suitable technical counter measures and optimization design scheme on well drilling,well completion and the reservoir reconstruction in this area.The research shows:The rock mechanics parameters obtained with the indoor experiment methods and the logging data methods have good correlation,On the basis of the prediction results of the research methods of this paper can fully satisfy the needs of engineering construction;the formation pressure of the Xujiahe formation on different regions are difference,the Chuanfeng 188 well in the eastern area is relatively low(1.2MPa/100m)and the Dongfeng 3 well in the north is relatively high(1.5MPa/100m);The rock strength of the continental formation increases with depth is obviously in the research area,the rock strength of the upper part of the Ziliujing formation and the bottom of the 4th member and the middle of the 3rd member of Xujiahe formation are significantly greater than other strata, the sandstone strength is nearly twice the strength of the shale in the same strata; the maximum horizontal principal stress direction are near east-west in the study area and the maximum horizontal principal stress direction of the Xujiahe formation is in the range of 96 to 116 degrees; the bear casing injection construction pattern is recommended to improve the construction capacity and to the increase of the net pressure inside the fracture in the reservoir with less natural fractures developed; combined with the drilling fluid performance optimization and the research achievements of bit type selection in this paper, the applications of unbalanced drilling to the work area improved drilling speed by more than 0.1~0.3m/h;after the optimization of the reservoir parameters, It finally obtained a higher production. |
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