Research On The Modeling Of Interlayers In Reservoir

The interlayer in a reservoir is one of the most important factors that affect the heterogeneity of the reservoir. Because of interlayers, the reservoir can be divided into several disconnected or half-connected flow units, which control the movement of fluid in the reservoir. Large number of practices in oilfields suggested that the types and the distribution .etc of interlayers can be regarded as main factors controlling the distribution of the remaining oil, especially when the reservoir of an oilfield has come to the high water-cut stage or ultra high water-cut stage.Based on the analysis of Guantao Formation fluvial reservoir in Gudao oilfield, this paper was focused on the studies of the distribution and the modeling of interlayers in reservoir and their controlling effect to the distribution of the remaining oil. The study of interlayers started from the core observation and analysis. Through core calibration of the well logging, the log distinguishing standard of interlayers was established, by which, the interlayers in those un-coring wells can be distinguished, and then, the types, genesis and distribution of the interlayers were analyzed.The upper member of Guantao Formation developed a set of fluvial sediments, among which Ng5 and Ng6 group developed a set of braided river sediments, and Ng3 and Ng4 group developed a set of meandering river sediments. The genesis of interlayers in fluvial reservoir include: at the stage when the flood is dropping, the muddy materials sediments; at some local area the weakening of hydrodynamic causes silty clay deposition; the energy fluctuations in each flood causes the formation of muddy interlayers; there are also fine sediments between different periods of fluvial sediment and so on. Lateral accretion layer of point bar in meandering river sediments and of channel bar in braided river sediments are the most typical and most extensive muddy interlayers in fluvial reservoirs. Take Ng6 sand group in Zhongyi area for example, based on the statistics of single well interlayer data of the more than 1,000 wells in the study area, the interlayers isopach maps of each layer were drown and the distribution of interlayers in each layer were discussed. There are a variety of methods for interlayer model building to choose from; in this paper the stochastic simulation method was chosen. Based on the statistical information of more than 100 wells, the interlay model of Z12-9 well group in Zhongyi area of Ng65 was established, according to the building model, the spatial distribution rules of braided river reservoirs were analyzed.The existence of interlayers plays a key role of controlling the distribution of the remaining oil. In this paper, the controlling effect of different forms and different occurrence of interlayers to the remaining oil was discussed, and also, several pieces of corresponding suggestions were proposed, in order to achieve a better development result.