A Research On Lithologic Reservoir Prediction In Liuzan Block In Nanpu Depression

Exploration on lithology-stratigraphy oil-gas pools is the main direction of reserve increasing in the future. Theories and techniques of the prediction of subtle reservoirs are mature. To most continental rift-subsidence basins in east China, sedimentary and structural movements are complex in heave margin areas and prediction of lithologic oil-gas pools still need lucubrate. Seismic continuity is dispatch and well contrasting is difficult in this area. The paper established the stratigraphic frameworks, studied depositional systems and then predicted reservoirs finely by reservoir inverse.Aimed at the difficulty in well contrasting, the paper used well-seismic combined classification demarcation technique in stratigraphy division. Seismics controlled the large scale contrasting and wells controlled the small scale contrasting. Sequence stratigraphy frameworks were established by dividing 3 second-order sequences, 7 third-order sequences.Space time evolvement seismic interpretation showed the Liuzan structure was a roll anticline complicated by faults. The anticline formed between two different subsidences in Sha 3 and Sha1 periods. The anticline was nipped in Bogezhuang fault and Gaoliu fault. In the east, Gaoliu fault's side avulsion during Minghua period further complicated the Liuzan anticline. Different subsidences in this area were controlled by Bogezhuang fault's imbalance activity. The imbalance activities also controlled the structural configuration and fault characters. North north bend normal faults developed in Liuxi and Liuzhong areas and south bend faults developed in Liudong area.Sedimentary systems were identified and main sedimentary facies were established in Liuzan area including brim fans of steep slope, shallow lake, half-deep lake and fore-delta turbidic fan of low-lying of middle part and braided fluvial delta-coastal shallow lake of southern gentle slope. Distribution of depositional systems was studied. Liuzan area was on the deep slope margin and the main depositional systems were fan delta and sublacustrine fan and lacustrine system. Lacustrine system was developed in LST of SQ2 and fan deltas were developed in TST and HST. There developed multi-sources, so the lobation shape of fan delta was evident. Alluvion was the main depositional systems of SQ4 and fan deltas were main depositional systems of SQ5.On the basis of reservoir analysis, resistance logging was used in impedance inverse. In inverse, analysis of seismic attribute and processing of sedimentary rule inhibiting in log standardization helped in realizing of facies controlling reservoir horizontal prediction. Inversion result showed profile and plane information inosculated well with sedimentary rules and drilling results.Analysis of sequence stratigraphy, depositional systems and structure frameworks and oil and gas distribution rules predicted potential reservoir targets finely. SQ2, SQ3 and SQ4 developed lower fans in the Liuxi slope break. Total exploration degree was relatively low and Liu 9 gained industrial oil in SQ4 sequence. So Liuxi area was the best potential area of lithology reservoirs. SQ5 in Liuzhong area was favorable area in finding fluvial lithology reservoirs.