Comprehensive Geology Research For S₃² Formation Of Block Leng 41 Of Lengjiabao Oilfield

This paper presents a comprehensive geology research for Block Leng 41 which is the major block of Lengjiabao oilfield in Liaohe basin. Block Leng 41 is located within Panshan county of Liaoning province, belonging to Lengjiabao Oilfield Development Company. Structurally, it lies in the mid-north of Lengdong faulted anticline belt of eastern actic region of western depression of Liaohe fault basin. S₃² is the major target development formation, with the proved oil-bearing area of 2.3km² and OOIP of 2189×10⁴t in 2003. Submarine fan sedimentary system in steep shape is developed in this block, the net pay thickness of single well is thick, and average oil layer thickness of Block Leng 41 is 134.3m,and average stock tank oil viscosity is 68816mPa.s at 50℃, which is edge bottom water ultra heavy oil reservoir. Now, this block is at the middle-late development period with obvious problems, such as limited development by huff and puff to enhance oil recovery, and critical situation for stable production. In order to guarantee sustainable development, a comprehensive geology research is needed to be carried out to bring about a better understanding.A compressive research of S₃² interval of Block Leng 41 is conducted based on reservoir geology, and starts from geology, seism, logging by adopting fine strata correlation, accurate seismic interpretation, sedimentary micro-facies research, interbed study, geologic reservoir modeling. Strata are classified by sedimentary cycle combination, sands thickness, and performance under the control of marker bed according to correlation and classification principle. Fault and structure characteristics are studied by using drilling and 3D accurate seismic interpretation results to solve the problem of complex oil water relationship. Sedimentary facies mode is determined, log facies is classified and vertical evolvement and areal distribution of sedimentary micro-facies are studied based on petrology, sedimentology and core data. Reservoir characteristics are studied, including petrology, petrophysical property, four-property relationship, heterogeneity, micro pore configuration. And the interbed sorting, performance, areal distribution, and its effect on reservoir development are also studied. Through the systematic analysis and study about reservoir, oil gas distribution and controlling factors are further clarified, and 3D geologic model is established, providing a geologic basis for determining remaining oil distribution according to field production data and dynamic analysis method integrated with numerical simulation method, offering technology supporting for establishing effective development strategy, improving reservoir recovery, realizing effective, reasonable, scientific development at middle-late period, and also providing operative reference for basic research for massive reservoir in Liaohe basin, and broadening the research ways for similar oilfields which need to convert development methods.