Research Of Logging Evaluation For Fractured Reservoir In Jidong Oilfield

Compared with clastic reservoir, the carbonate reservoir shows more significant characteristics of fracture. The logging interpretation and evaluation of fractured reservoir is confronted with more difficulties than that of conventional homogeneous porous reservoir because of that it has more complex structure of pore and stronger anisotropy than the conventional homogeneous porous reservoir. The fractured reservoir in Jidong oilfield has the characteristics of favourable reservoir forming condition, strong diagenesis, multi-type and great variation and complex distribution of reservoir, complex reservoir type and so on. There are mainly three difficulties faced in the petroleum exploration and development: (1)the exact identification of reservoir lithology;(2)the exact evaluation for reservoir physical property, especially for porosity and fracture porosity; (3)the evaluation for oil-bearing properties, the computation of hydrocarbon saturation, the oil-gas-water distribution and its interface's determination. Based on the charactersitcs of fractured carbonate reservoir and main problems faced in the evaluation of fractured reservoir in Jidong oilfield and proceed from actual conditions, this paper builds up a set of relatively perfect and effective method of logging evaluation for fractured carbonate reservoir by combining theory with practice systematically.The lithology of fractured reservoir where the carbonate dominates in the research area is complex. It has own characterstics which are similar to ordinary reservoir. Based on the systematic analysis of logging response characteristics for different lithology reservoirs, this paper builds up the regional lithologic identification standards using logging data.The dual lateral logging responses of fractured formations computed by 3-D finite element, such as single fracture, fracture group, cross fracture, fracture in macroscopic uniform anisotropic media, are researched at any arbitrary angle. The function relation which is established between response of dual lateral logging and formation parameters in carbonate reservoir is applied to analyze the field data.By deeply analyzing the responses of rock physical parameters, such as electrical parameters, acoustic parameters, radioactive parameters and abnormal response of logging curves, the qualitative identification of fracture zone is achieved and fractured interval is determined; The fracture type is classified and the logging response model of different fracture types is established. The parameters, such as fracture porosity, fracture permeability, reservoir saturation, shale content, total porosity, are respectively computed. Combined with the advanced logging technology, the comprehensive evaluation for reservoir parameters is carried out.Using the data of advanced logging technology, the evaluation is carried out accurately for reservoir and the discrimination method of fracture properties and standard are researched. The accurate calculation method of fractured porosity is proposed; Compared the conventional calculation results calibrated by imaging logs with the results by the proposed method, the fracture is identified effectively.Based on the research of logging response characteristics of well testing data and testing interval, the classification standard for reservoir is studied. The reservoir in this block is classified into three grades and the classification standard is proposed for conventional logging data. According to the characteristics of complex lithology and strong heterogeneity of fractured reservoir in Jidong oilfield and taking conventional logging method as main and anvanced logging technology as subsidiary, the logging interpretation model of reservoir with different fracture types is built up. The comprehensive evaluation method of reservoir corresponding to the reservoir characteristics in Jidong oilfield is researched.