基于储层物性时变的稠油底水油藏高含水期精细挖潜技术

A New Potential Fine Trapping Technology for High Water Cut Stage in Heavy Oil Reservoirs with Bottom Water Based on Physical Properties of the Reservoir Varying over Time

  • 摘要: 现有稠油底水油藏水锥变化计算公式均未考虑由于长期大液量冲刷引起的储层物性变化,导致计算出的水驱波及体积偏大。为了准确描述高含水阶段水锥和水脊的变化规律及剩余油分布,考虑了长期大液量冲刷下储层物性的变化,运用等值渗流阻力法对波及区内外储层渗透率进行了等效表征,建立了考虑物性时变的稠油底水油藏水锥、水脊变化数学模型。分析可知,储层物性时变对水锥的影响十分显著,相同水锥宽度下,考虑物性时变的数学模型计算的波及高度较不考虑该因素的现有公式的计算值要小46.3%。将考虑物性时变的数学模型的计算结果与邻井测井解释结果对比,相对误差仅5.3%。根据渤海Q油田现有井距条件下利用考虑物性时变的稠油底水油藏水锥、水脊的接触关系,总结出了该油田3种井间剩余油分布模式,并针对不同模式给出了相应的挖潜措施。矿场先导试验证实了基于储层物性时变的稠油底水油藏高含水期精细挖潜技术的可靠性、有效性,为稠油底水油藏高含水阶段挖潜剩余油提供了技术支持。

     

    Abstract: The current water coning variation formulae of heavy oil reservoirs with bottom water fail to take into account the changes in reservoir physical properties caused by long-term large liquid volume erosion, resulting in a relative large calculation result of the water flooding sweep volume. In order to accurately describe the change laws of water coning and water crest as well as the distribution of remaining oil in the high water cut stage, a mathematical model of water coning and water crest variations for heavy oil reservoirs with bottom water while taking into account the physical properties time-varying was established by considering the physical properties change of reservoirs caused by long-term large liquid volume erosion. Further, an equivalent seepage resistance method was used to implement the equivalent characterization of the reservoir permeability inside and outside the sweep area. The analysis showed that the reservoir physical properties that varied over time had a significant effect on water coning. Under the same water coning width, the mathematical model that took into account the factor of time-varying physical properties was 46.3% smaller than the calculated swept height that did not consider this factor. Comparing the calculation results of the former model with the results of the adjacent well logging interpretation, the relative error was only 5.3%. According to the contact relationship between the water coning and water crest of the heavy oil reservoir with bottom water considering the time-varying physical properties under the current well spacing conditions in the Bohai Q Oilfield, three types of remaining oil distribution patterns among the wells of this oilfield were summarized, and the corresponding potential trapping strategies were developed. The pilot test confirmed the reliability and effectiveness of this potential fines-trapping technology in the high water cut stage of heavy oil reservoirs with bottom water, could provide technical supports for recovering the remaining oil in those reservoirs.

     

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