Prediction Of Remaining Oil Distribution In Thick Reserviors In Central X6Distric In Daqing Oil-field

At present, waterflooding is the main development manner for most pools, during which distribution of oil and water varies with time and becomes more and more complicated, the motion law of oil and water is difficult to expect, and distribution types and fetures of remaining oil are ample, induced by geological factors and engineering practice.To improve oil recovery, it is essential to study the distribution of remaining oil and analysize the motion law of oil and water or to predict the pattern characteristics of remaining oil, which is basis for adjusting the development in high water cut stage.Located in North of Xingshugang Structure, the middle part of Daqing Placanticline Structure, Songliao Basin, since water injecting in1966, the Central X6district has been exploited in a high speed for more than40years and stepped into the high water cut period. The distribution and prediction for remaining oil also becomes the key prob-lem for the oil-field. However, the distribution of remaining oil is complex because of the continental sedimentary system, multiple types and rapidly changing reservoirs and the long stage waterflooding. In resent years, several studies have done on the stratified reservoirs and the well pattern, but few work done for single sandbody and the remain-ing oil in the sandbodies. Besides, Daqing Oil field is faced with two huge challenges. On the one hand, owning to the improvement of exploration degrees and the quality de-crease of proved reserves, producing extent of new reserves and remaining reserves be-comes lower and lower. On the other hand, because of the problem of high composite water cut, high oil production rate, high degree of reserve recovery, low R/P ratio and low recovery ratio", a huge number of oil hasn’t been produced. So improving the degree of cognition is becoming more and more important and urgent. With the support of the Special Grand National Science Technology Project, the paper digests the prede-cessors’research, pays attention to combining the fine geologic research with develop-ping dynamic data of the oil-field, and analyse qualitatively the distribution and forming prcess from the angle of geological factors, using the dynamic data.The specific main several researches are as follows:1Reservoir geology study. The sandbodies of thick reservoirs are described accord-ing to the static geological data, the relationgship between core and logging is set up based on the cores and logging data, and the fine sequence formation framwork is built in accordance with the strata compareson results. The types, distribution and evolution of the microfacies are studied and4kind of layer structure models.2Analyse of the waterflooding features in inspection well. And the stastical results show that the waterflooded extent is high as a whole. For distributary chan-nels, the extent of the under parts is stronger than the upper.For sand bars, it is opposite. And the extent is uniform for the sand sheet. Besides, owning to the inter-calated bed or low permeality ones, the waterfloodeding characteristics are complex. 3Considering the deployment history of the well pattern, counting the water flooded layer logging interpreting results and using the geological research results, regularity of the flooded extent and acreage of different types of sandbodies in each well pattern and potential area of remaining oil are finally worked through. The channel sand is waterflooded in the early stage and the extent is generally strong. The extent of interstream sandbodies is middle to high and that of the sand sheet is low to middle. The waterflooded extent and the waterflooding ratio of each class raises steadily, especially the tertiary infilling well (2006).4With the static and dynamic material, qualitative and quantitative method combined, from the angle of the forming factors of remaining oil, based on the results of fine geological discription and according to the statistical results of inspection wells and logging flooded layers data, the remaining oildistribution characteristics of majior reser-veiors are studied by means of dynamical analysis.5According to the waterflooding law of the core well and distribution features of remaining oil, the paper analysed not only the main control factors, types and potential area of remaining oil, but also the formation mechanism of remaining oil. And the5kinds of distribution types are finally included. The forming modes of remaining oil were finally concluded as follows:Contiguous distribution and relatively poor oil reser-veoirs type, retained region type, intraformational unwatered out reservoirs type, the nook of remaining oil distribution types and voidage-injection imbalance types.And through the analysis, in different oil layers the remaining oil distribution patterns and formation mechanism vary with each other.With the static and dynamic material, qualitative and quantitative method combined, the article reacquaints the geologic feature of the Central X6District, figures out distri-bution of remaining oil by dissecting inspection wells, water flooded layer logging in-terpreting and analyzing dynamic data, and discusses the appolication of different data in oil-fields.