The Study On The Distibution And Evaluation Of Remaining Oil

Machang Oilfield is located in the south of Tangzhuang-Machang Structure of the Dongpu Depression. Through 30-years development, the study area has stepped into the extra-high water cut stage, which has leaded to the results that a large number of remaining oil distributes in the "blind angle" of waterflooding reservoir. In order to enhance the oil recovery, the distribution and influenced factors of remaining oil must be studied and reappraised systematically during the middle and late stage of waterflooding oil field.Based on logging geology, reservoir geology, sedimentary petrology and development geology, combined with depositional characteristics and deposition model of fan delta, this paper illustrated the control mode of the formation and distribution of the remaining oil with regard to the above questions and fully dissected the structure of reservoir.Stratigraphic correlation profile is established in the Machang Oilfield based on traceable mudstone layers and auxiliary marker bed.The analysis of sedimentary facies (outcrop, core and experimental analysis, ect) and characteristics of regional isochronous stratigraphic framework displayed the depositional environment of the Machang area is lake and delta.In the study area, the main development blocks, for example, Ma 11 block and Ma 19 block were mainly deposited in delta front, which main microfacies can be divided into underwater distributary channel, mouth bay, distributary bay, far sandbar and delta front sheet sand and so on. The distribution of sedimentary microfacies is drawn according to the plate of log phase to study the characteristics of sedimentary facies. The results have shown that the sedimentary microfacies is underwater distributary channel in the S3X11,7,8,9, S3X26,7,8,9,10 and S3x34,8, and distributary bay in the S3x12,6,10, S3X21,26, S3X31,2,3,5, and mud flat in the S3X13,4,5,11,12, S3X23,4,11, and S3X36,7,9.Combined with the research ideas of reservoir architecture in the Machang Oilfield and research about sedimentary facies in unit of monosandbody, study on combination of AHP and dynamic fit has been proposed. The fan delta reservoir structure in the Machang Oilfield can be divided into four levels including single sand level, composite sand level, single underwater distributary channel level and composite underwater distributary channel. Through analysis down by level, the reservoir structure and distribution of fan delta of the Machang Oilfield can be recognized.On the basis of conformational analysis and dynamic analysis, the main influenced factors of distribution of remaining oil in the Machang Oilfield were studied. The results showed that the distribution of remaining oil is controlled by sedimentary microfacies, reservoir architecture, geological structure, ect.