Research Of Concentrating Rules Of Remaining Oil In Fluvial Facies Positive Rhythmic Thick Formation

Aimed at land facies water flooding reservoir whose remaining oil disperses in general butconcentrates part partly, this paper, focused on fluvial facies positive rhythm thick formation in Shenglioilfield, master lined of the distribution rules of remaining oil, researches the decollating controleffection to remaining oil caused by interbed and preponderance flow path in the formation andestablishes the pattern of decollating control effection to remaining oil. Assisted by physical andnumerical simulation, this paper researches the mechanism of decollating control effection to remainingoil caused by interbed and preponderance flow path in the formation and build up the quantitativepredicting model to establish the general technology for interbed and preponderance flow pathdescription and prediction. In this basis, the aim describing the distribution of remaining oil, recoveringit and improving the recovery ratio can be achieved. The main fruit and innovation of this paper islisted as follows:(1) Two type of interbed decollating control effection to remaining oil are build up, they are partialinterbed controlling effection and central interbed controlling effection. Assisted by physical andnumerical simulation, the quantitative relationship among the scale, the position and the areas of theinterbed and the concentrated area of remaining oil is researched, and the quantitative prediction modelis established.(2) The conception is created that is preponderance flow path in the formation. The macro andmicro static and dynamic characters are researched, the mechanism of controlling effection that thepreponderance flow path in the formation result in inefficient injecting water cycle while remaining oilconcentrated part partly at the top of the formation that is not in preponderance flow path, quantitativeprediction model is established that can predict nondimensional remaining reserves under differentgeological and developing condition and injected PV of water.(3) A series of technologies are applied to achieve the aim of building up the three dimensionmodel of the interbed. They are sediment theory and formation sedimentary structural unit technologyby which the distribution rules of interbed in different sedimentary type can be researched in threedimensions and interbed distribution knowledge database can be build up, high definition log and fineinterpreting technology by which the interbed in well point can be discriminated, rhythmic unitcollating technology, physical property breakage technology and conditional simulation technology bywhich the interbed distribution among wells can be predicted.(4) Preponderance flow path in the formation is discriminated by the reservoir testing, tracerproducing curve, injector well drawdown curve and production performance. According to the effectionto the forming and transformation of the preponderance flow path in the formation that caused bypermeability max-min ratio, plan across permeability ratio, oil/water viscosity ratio and intensity ofinjection and production, the prediction model of preponderance flow path in the formation can bebuild up and the forming condition and occasion of it can be quantitatively predicted.(5) According to the theory that decollating control effection to remaining oil casued by interbedand preponderance flow path in the formation, interbed and preponderance flow path in formation canbe described and predicted, and remaining oil concentrated part partly at the top of the positiverhythmic thick formation can be defined. The research fruit was applied to practice and remarkablesuccess was got. Here is an example, Ng53 formation of Zhongyi section in Gudao oilfield is fluvialfacies positive rhythmic formation, the general water cut was 92.7 percent, 15 wells was designedaccording to the theory and remarkable benefit has been got, at the beginning stage the production was29.5 tons per day per well, and the general water cut was 40.3%, 111 thousand tons oil has beenproduced by now.