Reservoir Prediction And Evaluation Study On Putaohua Oil Layer In The North Of Gulong Depression Of Song-liao Basin

The Putaohua oil layer is a dominate hydrocarbon zone in the north of Gulong area of Song-liao basin. But the evaluation,exploration and development to Putaohua reservoir were restricted because of the complicated geological conditions (include fault distribution , thin sand shale interbedding and complicated sandstone distribution)and the complicated oil-water distribution. This paper was about the prediction ,evaluation and comprehensive study on Putaohua oil layer meeting the needs of exploration and development .Identification marks and sequence of sedimentary facies and model of micro-faces sedimentation were built in this paper, based on the stratigraphy correlation and thin layer division and contrast to the north of Gulong area.This paper also had an overall analysis to the sedimentation system,facies characteristics, source direction, the sand body reservoir distribution and distributing feature of micro-facies .Comprehensively utilizing cores, logging, well logging and analysis assay data, this paper studied the petrologic characteristics, reservoir property and the relation between reservoir property and oil-bearing characteristics of Putaohua oil layer. This paper studied prediction method for the thin interbeds of sandstone and mud stone. Based on the reservoir simulation, stochastic simulation, lithologic simulation and porosity simulation, this paper revealed single sand body's distribution, determined and quantitatively calculated the single sand body'boundary of important regions and favorable reservoirs.Base on the studies on the controlling factors and resrvoir types,this paper put forward main hydrocarbon enrichment factors and oil-water distribution laws.Understanding and conclusions:The paper determined the stratigraphic contrast scheme of the top and bottom of Putaohua oil lay. Three small layers were divided to the north of Gulong area and eight small layers were divided to the oil domain and their surround area.Based on the cores, analysis assay data and logging, according to the identification marks of sedimentary facies, this paper established rock-logging-facies transformation model from the typical interval. The sedimentation system of the north of Gulong area is delta-lacustrine depositional system. There are 5 kinds of micro-facies in total: underwater distributary channel, river mouth bars, far bars, inter branch channel and shore-shallow lacustrine sediments, deep and semi-deep lake facies. This study lays a good foundation for the study on the reservoir prediction,physical property changes and reservoir types and distribution.This paper determined reservoir prediction method and technical process of thin sand and shale interbedding in the north of Gulong area. The reservoir prediction can be done by the process of the stochastic simulation, lithologic simulation and porosity simulation. Determine and quantitatively calculated the favorable reservoirs'boundary of important region.Based on the deep analysis of plane and vertical distribution of single reservoir,this paper determines that although oil and water interlayer frequently on vertical formation, oil–gas aggregation follows the regulation of differential gravity action which the oil distributed above the water. The plane reflects the characteristics of edge water drive reservoir.The reservoir types and distribution closely relates to the sand distribution and the structure background. The main conditions forming lithologic reservoir closely relates to the property change of the sand from different source and the sand from different sedimentary faces. Multiple sources and different structures influence the distribution of Putaohua oil layer. Fault block-lithologic reservoir and structure -lithologic reservoir ( sand layer up thinning out) develop in slope area. Sand lens reservoirs and lithologic reservoirs which the underwater distributary channel sand cut by fault develop in syncline area.Low Porosity and low permeability reservoir, relatively flat structure background lead to worse oil-water differentiation and high water cut reservoir. The direct reason of large proportion wells of commingled production of oil and water is that the vertical fractures made by the fracturing treatment communicate the water lays near the oil lays.