High-resolution Sequence Stratigraphy Analysis And Its Application To Oil Production Of Pucheng Oil Field

The foundation of reservoir model and residual oil prediction have been the core of reservoir detailed description for improved oil production and enhanced oil recovery. The traditional way of sandstone correlation based on the geometrical similarity of well-logs which emphasizes "based on the cycle and correlating from larger to smaller" has shown its theoretical limits when explaining the correlating and the scale, geometry, continuity, connectivity of sandstones and the law of the reservoir property. It has been an urgent and difficult subject to find new theory and methods to solve the reservoir correlation and property prediction.It's a new way to correlate strata and found framework of reservoir through the process-response analysis in the base-level cycles. And it is also possible to analyze the reservoir property in reservoir framework.Taking the reservoir of zonation 6-10 in S32 of Pucheng Oil Field in Henan Province as an example, we founded the detailed reservoir stratigraphic framework through base-level correlation. In the strata frame, sediment distribution and its development are discussed based on sediment volume partitioning and facies differentiation analysis. Reservoir heterogeneities and its relation to base-level are also discussed. The analysis of primary oil distribution shows the base-level controlled oil distribution in reservoir.In this paper, subjects as following are discussed in detail.1 Based on the analysis of sedimentary structure and sedimentary energy, the facies model was founded.Pucheng Oil Field is tightly adjacent to the boundary fault of Dongpu Depress, and it is easy to develop fan-delta and sub-fan on this location. In fact it is easy to find the sediment supply of the studying area is mainly from eastern high through the thickness map and its sand-content map. Shale is mainly dark gray to black, some of them is oil shale, so the sedimentary environment is in deep and reductive conditions. The fact that grain of sand is fine or silty, with thin layer and little-scale scours means that the water energy was low. Grain analysis tells its transiting character between turbulent flow and drag flow with the same character as sub-fan. In the core, every sequence is positive rhythm and debris flow that is not developed in delta was also found. Thick sand beds are always made of several layers of single normal cycles. From all the characters above, it is easy to say that it was developed in the sub-fan environment.In the core, more than 20 kinds of lithofacies was recognized and more than 6 type microfacies including channel, inter-channel, sheet-like sand, lake and salt lake was distinguished.2 Founding stratigraphy framework through base level analysisFour scales cycle was distinguished from the core. Very-short term base level cycle is equal to a sediment incident. Rock in the cycle is made of single lithofacies or lithofacies sequences that made a stratigraphic pattern, it is always made of one single environmental element. Short term cycle is a sets of sedimentary incidents, which indicates a stage of water depth changing obviously. In the studying area, it is corresponding to the development of one lobe in a fan of the sub-fan. In the profile, it is often made of one to two environment elements, which indicates a progradation or regression. The sand developed in this stage is equal to single sandbody which is the smallest scale for correlating between wells. Middle term cycle is related to an obvious water changing. In the studying area, it is defined as the process of one fan development. Long term cycle is a sets of large scale water changing which forms a local progradation and regression. In the studying area,it is defined as the foundation of fan-complexity. There is response in the seismic profiles for this scale, which made it possible to make correlation through the well log under the restriction of seismic.In the studying zone, one long term cycle, 6 middle term cycles and 27 short term cycles was identified and correlated. Base on t...