| In recent years,China’s oil and gas exploration of increasing the natural gas exploration efforts,formed a rapid growth of natural gas reserved.Natural gas as a clean energy and important petrochemical industry raw materials,to change China’s energy structure,improving the environment and development in petrochemical industry benefit mankind,it will play an immeasurable role and be paid more and more attention to.Kuche depression of Tarim oilfield in a new generation foreland basin nature,has extremely rich oil and gas resources,especially natural gas resources.Main oil formations lithology of Kuche depression is compacted sandstone,logging and well logging data showed that fracture is very development in the region.The tarim oilfield kuqa foreland basin sandstone formation development of high tilt angle fracture,DaBei coring wells crack general is70°-90°,width of0.5-3mm,drill extension in7cm,the original surface seam rate around50%,part of the core is broken hole section,is typical fractured reservoir of cracks developmented.The cracks not only control the distribution of reservoir,and is the main fluid flowing channels of the fractured reservoir,is important control factor of soil and gas well productivity. Because of the complex fracture distribution,the use of this kind of reservoir mining benefit common is poorer,and has not part of spent.Therefore,research of crack interstifial flow rule has become priority issue of the reservoir increasing exploration and development benefit,and also is one of the oil geological research important issue.It has important meaning to promote such oil and gas reservoir exploration and development.About vertical cracks well seepage rule research has been a tremendous achievement,many scholars have proposed instable seepage analysis theory of reservoir-crack system,and was accepted and widely used.The interstifial flow model mainly includes:double linear flow model,2D plane models,three linear flow model and elliptic flow model,etc.The model is put forward in condition of only one pressing crack,but to the natural development of the fractured reservoirs is the assumption that must not established.Although to vertical cracks well seepage rule research is mature,but for development of cracks research in many branches vertical cracks well are rare.In exploration and development process of Tarim oil field,the fractured reservoirs exist generally,crack is complicated,the damage law between fractured reservoir and conventional reservoir are obviously different.It has not formed a set of effective fractured reservoir protection technology,and can’t accurate evaluation and prediction to single well productivity.Necessary to carry out in-depth large size core pollution test evaluation and fracture diverting capacity evaluation research,so that more scientific guiding try oil solution design.In this paper,the object is the tarim kuche depression fractured sandstone reservoir,the main research contents:(1) Evaluation experiment of big size core pollutionEstablish experiment of big size core pollution to evaluate drilling fluid effect on pollution degree of reservoir,analysis differential pressure,temperature,time to the influence of reservoir pollution degree.(2) Skin factor and permeability research of pollution coreAccording to the strata pollution physical model,based on seepage theory and skin factor definition study formation damage skin factor calculation method in different damage mode.(3) Instable seepage analysis of more fractured system well vertical cracksBased on the boundary element theory,establishing seepage field simulation method of more fractured system and seepage flow mathematic model of branch vertical cracks well,analyzes different fracture characteristic parameters on the effect of instable seepage.(4) Productivity factors analysis of low hole fractured sandstone gas reservoirStatistical analysis matrix and cracks parameters on the influence of capacity,establishing productivity prediction model of low porosity fractured sandstone gas reservoirs,analyses the crack characteristics effect on capacity.(5) Productivity prediction method research of low hole fractured sandstone gas reservoirOn basis of statistics analysis,combining percolation theory establish productivity prediction method of low hole fractured sandstone gas reservoir.This paper obtained the following results:(1) Finished big size core pollution evaluation experiment:analysis differential pressure,temperature,immersion time on influence of reservoir pollution degree.(2) Theory research skin factor and permeability of pollution core,obtained the damage skin factor calculation method under different damage mode.(3) Decomposition the skin factor of fractured sandstone system,showed that the skin factor of crack system relevant with the total system skin factor,matrix system skin factor,total system permeability,matrix system permeability and face the seam rate.(4) Based on boundary element theory established the seepage field simulation method of fracture system,through the simulationv showed that cracks in the position, size and shape all have different degree influence on the oil reservoir streamline distribution.(5) Established seepage flow mathematic model of low hole fractured sandstone gas reservoir,analysed crack characteristics parameters on effect of instable seepage.(6) Established productivity prediction model of low hole fractured sandstone gas reservoir,analysed the crack characteristics parameters on the effect of productivity capacity,obtained productivity prediction method of low hole fractured sandstone gas reservoir.(7) Compiled productivity prediction softwarea of low hole fractured sandstone gas reservoir,using the software to predicti DaBei101well C1-3layer and another two layers,the predicted yield close to measured output,error less than15%. |
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