Study Of Well Test Analysis And Productivity Prediction For Multiple-fractured Horizontal Wells

Recently,the new type of unconventional reservoir has attached a great deal of public interest in energy development field,the unconventional resources are abundant and widely distributed in China.However,the permeability is ultralow of these reservoirs,which the reservoir stimulation technology is needed to obtain commercial production.Fortunately,the drainage acreage can be increased with horizontal well technology,large scale multiple hydraulic fracturing technology can break up matrix to form complex fracture network,enhancing the reservoir permeability greatly,therefore,horizontal wells with multiple hydraulic fracturing technologies have been an effect way in the development of those unconventional reservoirs.The interpretation and evaluation of well test data,together with productivity prediction after hydraulic fracturing is one of key technical problems that petroleum engineers urgently wants to solve.Therefore,the relevant research of well test analysis and productivity prediction for multiple-fractured horizontal wells(MFHWs)is carried out in this paper,and the following work has been done:Firstly,a new computing method for MFHWs is developed in this paper based on five-region composite reservoir model and superposition principle,a remarkable advantage of the proposed method is that the new method is no longer limited by constant flowing pressure or production rate conditions in comparison to the previous analytical/semi-analytical flow model,and can be used to calculate the wells under production rules of constant flowing pressure,constant production rate,intermittent production,intermittent flowing pressure,linearly changing production rate,linearly changing flowing pressure,or even more complex cases,in addition,this method has the advantages of quick calculating speed compared to numerical method.Therefore,the approach can be used to design well testing,interpret well test data,and predict productivity for MFHWs with consideration of any complex production history.Secondly,the characteristics of pressure transient curves are drawn,the pressure and its derivative curves can be divided into seven flow regimes,and influences of reservoir and fractures parameters are analyzed,which reveale the flow mechanism of MFHWs.Then,the method of well test analysis with consideration of any complex production history for MFHWs is developed based on multiple flow rate well test theory.Finally,the well test design is calculated by a diffset to behave the advantages of the well test method in this paper.Thirdly,the method of productivity prediction using transient inflow performance relationship(IPR)curves with consideration of complex production history for MFHWs is developed.Meanwhile,the characteristics of transient IPR curves are discussed comparing to conventional IPR curves.Then,The effect of production rules,production history,reservoir permeability,linearly changing of production rate and linearly changing of flowing pressure on transient IPR curves have been analyzed,in addition,physical meaning of slope and intercept on IPR curves are expounded.The results obtained can provide theoretical foundation for productivity prediction analysis of MFHWs.Finally,the well pressure data for a multiple-fractured horizontal well is interpretd with the well test method developed in this paper,the reservoir and fractures parameters are obtained,and then the production rate and flowing pressure are macted based on the interpreted results,on this basis,taking the end point of well test as a starting point,the well productivity is predicted using transient IPR curves with consideration of production history.The research of this paper provides theoretical guidance and basis for well test analysis and productivity prediction of MFHWs.