Comprehensive Evaluation & Development Object Blocks' Optimization Of Ma5-4-1 Reservoir In The Northern Part Of Jingbian Gas Field

With the aggravation of the exploitation degree,the productivity construction projects of Jingbian gas field has expended to the peripheral area in recent years.This paper has made a refined research of the characteristics of Ma5-4-1 reservoir depends,on the collection and treatment work of the data as well as the deep analysis.Based on the thorough understanding of the reservoir bodies'temporal-spacial distribution regularities,the comprehensive evaluation of the reservoir,together with the clear understanding about that the formation and development process of the carbonate reservoir in the study area is very complex with sedimentary facies,diagenesis and peleokarst geomorphology as the three main controlling factors,conclusions come as follows:1.Sedimentary environment is the precondition of favorable rock types for the reservoir. Analysis of the sedimentary environment,the slice analysis and the map complation of the advantage facies shows that the evolution of sedmentary environment has made the differences between the a member and the b member of Ma5-4-1 reservoir.It was transgression stage when a member developed,which has made intertidal dolomitic flat as the main sedmentary environment.While it was regression stage when the b member developed, which has made a large member of supratidal dolomite flats and gypsum-dolomite flats as favorable sedimentary facies for the development of reservoir.2.Diagenesis is the important guarantee to form favorable reservoir space.The diagenesis characteristics or Ma5-4-1 reservoir in our study area is as follows:karstification and dissolution in the supergene stage are helpful for the reservoir's development,and the penecontemporaneous dolomitization has improved dissolution although it hasn't formed favorable pores;compaction,pressure solution and recrystallization does no good to the reservoir's performance.3.Tectonic evolution is a favorable factor for proceeding the diagenesis.The overlying Ordovician strata of MaS-4-1 layer in the northwest of the study area has suffered serious deletion,which is beneficial to the dissolution in both vertical and longitudinal directions by helping the infiltration of the karst water.The solution pore,fracture and intercrystalline pore are the main reservoir space types or the Ma5-4-1 layer in this area.Most of the solution pores are filled with several fillers rathe than one single filler.The packing structure is complex,but the extent is just general wih a lot of intercrystalline pores and intercrystalline solution pores left.4.The complexity of pore-structure is the microscopic embodiment of reservoir heterogeneity.The permeability of Ma5-4-1 layer is the mostly associated with porosity in the exponential function,provided by the analysis of physical property measurement.When the porosity is higher than the critical value(almost 80%),the increasing trend of permeability is very obvious as the increase of porosity.This indicates that the foundation to improve permeability is solution pores'development and the key is lies in the development of dissolution fractures and the fractures connecting pores.According to the results of high pressure mercury intrusion associated with observation of core and cast thin slic,the pore structure types has divided into five kinds,among which the a member of Ma5-4-1 is mainly of fracture-vug-pore type(account for 37%) with a accessory fracture-vug tipe(account for 21%) while the b mernber is mainly of microfracturc-microporous type and microporous type (account for 37%) with a accessory fracture-pore tipe.5.Classification evaluation of reservoir is precondition of development object blocks' optimization.On the basis of the isoline maps'superposition combined with the distribution of sedimentary facies and the pore structure types,MaS-4-1 reservoir is divided into three types of favorable areas:typeâ… ,typeâ…¡and typeâ…¢.The reserve-permeate performance of Typeâ… and typeâ…¡is better.Results of reservoir classification evaluation agree well with open flow potential of single well performance.The sum total area of typeâ… and typeâ…¡ has occupied 40%,while their reserves account for 60%of the total reserves in the favorable areas.Thus,typeâ… and typeâ…¡favorable areas are the most prospective object blocks to explorate and exploit in the north part of Jingbian gas field.Compared with the reserve-permeate performance of Ma5-4-1 reservoir in the easten part,the northern part of Jingbian gas field has a better developing prospect.