Reservoir Accurate Correlation And Properties Characteristics Of Anpeng Deep Series At Zhao'ao Oilfield

As multi-source fan delta deposits, Anpeng Deep Series at Zhao'ao Oilfield is located near to the source and characterized by small scale, varying fast laterally and poor superposition vertically. Few people have carried on systematic research on the sandbody distribution, sedimentary microfacies and reservoir validity. As waterflooding is used deeply, the contradiction between water and oil stratum becomes more and more obvious. Thus, it is emergent to carry on reservoir accurate correlation, find out the sedimentary microfaces distribution and study the validity of reservoir on the base of properties.In the subject, we confirmed the sedimentary facies model of Anpeng Deep Series fan-delta deposition. Based on high frequency sequence division, high precision sequence stratigraphic framework taking parasequence as elementary unit is established. After the subdivision of single sand layer, its isochronal correlation style limited by parasequence boundary is formed. According to its thickness and log curve shapes, we have analyzed the distribution of single sand layer's sedimentary microfacies and its properties' distribution rule on the plane. Using three levels hierarchy of flow unit and properties of single sand layer, we have studied the vertical and planar distribution of flow unit and forecasted the distribution of residual oil. We mainly got the flowing achievements:(1) According to the recent research of fan delta abroad and domestic and formers' research achievement, by the means of analyzing core, outcrop and petrographic thin section, we find that Anpeng Deep Series belongs to fan delta deposit in which only fan delta frontier and pre-fan delta subfacies are developed. Developed along steep slope, with mountains behind, Anpeng Deep Series belongs to lacustrine fan delta. It is the junction of two or three lobes on the plane and the congruence of multi-stage fan deltas. Dominant with gravel pebbled sandstone and median-fine grained sandstone on lithology, it has the following two sandstone types: feldspathic litharenite and litharenite. The detrital components are poorly rounded and graded. There are mainly clumpy structure and cross bedding developed. Gravel facies and median-fine grained sanstone facies are recognized here. The following log curve shapes such as box bell funnel or the combination of one another, mainly representing sedimentary microfacies: subaqueous distributary channel, river mouth bar, front sand sheet etc. On seismic profile, Anpeng Deep Series shows wedge and sheet forms. Its seismic facies are charactered by low—medium-high frequency high—medium-low swing discontinuity—relative continuity reflection.(2) According to the basic theory of high-precision sequence stratigraphy, two types of parasequence were distinguished from Anpeng Deep Series: parasequence with river mouth bar-sand sheet deposits and composite parasequence. There are three types of log response to the parasequence boundary, namely aggradation/progradation, retrogradation/progradation and progradation/progradation. Three types of parasequence sets can be recognized. They are...