Oil & Gas Geology ›› 2003, Vol. 24 ›› Issue (3): 219-222.doi: 10.11743/ogg20030305

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TRAP FILL OF LITHOLOGIC POOLS AND ITS MAIN CONTROLLING FACTORS IN DONGYING SAG

Zeng Jianhui1,2, Zhang Shanwen3, Qiu Nansheng1,2, Jiang Zhenxue1,2   

  1. 1. Key Laboratory of Petroleum Accumulation Mechanism, Ministry of Education, University of Petroleum, Beijing;
    2. Research Center of Basin & Reservoir, University of Petroleum, Beijing;
    3. Dep. of Petroleum Exploration, Shengli Oilfield Company, SINOPEC, Dongying, Shandong
  • Received:2003-05-27 Online:2003-09-25 Published:2012-01-16

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Abstract:

Dongying sag is the largest petroliferous region in Jiyang depression,Bohai Bay basin, which is the largest reserves distribution region in the lithologic pools, Jiyang depression. The main reservoir rock of lithologic pools in Dongying sag is sandstones in the middle and lower parts of the 3rd member of Shahejie Fm(Es3).The main source rock is mudstones deposited in the Es3 and the lower part of Es4. The exploration results of lithologic pools in Dongying sag show that the lithologic traps has a great variation in trap fill in Dongying sag. In order to study the trap fill as well as its distribution and controlling factors in lithologic pools,the methods of statistic analysis and principal factor analysis have been used. In general,the trap fill in the lithologic pools of Dongying sag ranges from 6.8% to 94.1%,with an average value of 46.5%. Among these,50% lithologic traps has less than 40% trap fill; 46.7% lithologic pools is more than 50%, only a few trap fill is more than 80%, with the maximum value of 94.1%.In terms of the types of sandbody,the trap fill in lithologic pools of sandbody isolated by source rock is relatively high,with the average 60%,while the trap fill of the lithologic pools laterally connected with faults is relatively low, with average about 40%. In stratigraphic horizon,the lithologic pools in the lower and middle parts of Es3 have trap fill as high as 52%, while the lithologic pools in the Es2 is only 23% trap fill.In the lithologic traps of Dongying sag,the most important factor of controlling the trap fill is hydrocarbon migration conditions, including the distances between lithologic traps and source area, the quantity of faults and the residual pressure within the lithologic traps. The second one is the hydrocarbon charge conditions, i.e. the petrophysical property (average porosity and permeability) and geometry (thickness and area) of sandbody.The oil source condition has a relatively less influence on the trap fill, because of more abundant oil source in Dongying sag.

Key words: lithologic trap, trap fill, Dongying sag

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