The Study Of Optimization Of The Horizontal Wells Volume Fracturing In Tight Sandstone Oil Reservoir

The tight oil of our country is widespread and abundant,which has become one of the important alternative resource in the petroleum industry.Horizontal well combined with multi-segment volume fracturing is an effective method to develop this kind of reservoir under the circumstance of water injection development.Chang-7 tight oil reservoir in Ordos Basin was took as the object of study to make a scientific survey of the current situation of volume fracturing technology in domestic and abroad.The characterization and the effect of the implementation in tight oil reservoirs of the Ordos Basin were analyzed including the rock mechanics,the development of natural fractures and the stress difference.Based on the analytical hierarchy process and the comprehensive evaluation theory,feasibility evaluation of the horizontal well volume fracturing was established,which could be used to evaluate the availability of the reservoir for horizontal well volume fracturing technology.Also,physical model,which could simulate the traditional types of fractures,was established on the basis of the similarity of voltage field and the seepage pressure field.The pressure contours in different transformed fracture shapes were drawn and the equal production potential was calculated.Mechanism of the effect on the water flooding filtration in different forms of fractures was elementarily revealed with the discovery of the optimum transformationfusiform volume fracturing with rectangle fractures.The fracture distribution pattern by means of the ligature was represented to describe the volume fracture of multi-segment volume fracturing,Furthermore,we established a numerical model of five-spot patterns with 1500 m horizontal part.Therefore,the system of development evaluation considering the early production capacity,long-term production capacity,accumulative production,the recovery,the water cutoff changes,the spread of oil saturation,the changes of reservoir pressure and the economic effects,was built,which can optimize the fracture length distribution,fracture spacing interval,the conductivity of the main fracture and other geometry parameters.The results show that the fracture distribution forms and fracture spacing intervals are sensitive to the development effect,while the conductivity of the main fracture is on the contrary.Horizontal well production capacity affected by the volume of fractures and injected water,water channeling will appear when the volume of fractures is too large.The fracture distribution of five-spot patterns with 1500 m horizontal part existed optimum parameters of 14 fractures and 15?m2·cm flow conductivity The field test used the geometric parameters,which has been systematically studied,and the development effect was prospective.The results provide theoretical guidance for the Horizontal well combined with multi-segment volume fracturing of tight oil reservoir,the stability and economic efficiency of the technology will be promoted.