超压泥岩盖层中断层垂向封闭能力研究方法及其应用

摘要

In order to study the role of fault in hydrocarbon accumulation and preservation ,a comparative study was car-ried out on vertical sealing capacity of faults between overpressure and normal pressure mudstone caprocks .On this basis , displacement pressure of fault rock was calculated by using the empirical relationship between displacement pressure and shale content and buried depth .A set of methods for evaluating the vertical sealing capacity of fault in overpressure mud-stone caprock was established and applied to Surennuoer fault zone of Wuerxun Sag in Hailar Basin .The displacement pressure of faults was quantitatively calculated ,and the vertical sealing ability of overpressure mudstone caprock was eva-luated.The results indicate that K1d1 overpressure mudstone caprock has a weak sealing capacity in Surennuoer fault zone and is unfavorable for hydrocarbon accumulation and preservation .This result is in good agreement with the phenomenon that oil/gas are widely distributed in this fault zone but the reserves abundance is low .This shows that this method is fea-sible for quantitative calculation of the vertical sealing capacity of fault in overpressure mudstone caprock .%为了研究断裂在油气聚集与保存中的作用，在有、无超压泥岩盖层中断裂垂向封闭油气作用及差异性研究的基础上，针对断层垂向封闭能力的对比，利用围岩排替压力与其泥质含量和压实成岩埋深之间的经验关系，计算并求取断层岩排替压力，从而建立了一套超压泥岩盖层中断裂垂向封闭能力的研究方法，并将其应用于海拉尔盆地乌尔逊凹陷苏仁诺尔断裂带内，定量得出断层岩排替压力，完成苏仁诺尔断裂超压泥岩盖层内的垂向封闭性评价。结果表明，苏仁诺尔断裂在大磨拐河组一段具有较弱的封闭能力，不利于油气聚集与保存，这与该断裂带油气分布广但储量丰度低这一现象吻合较好，由此证实，该方法用于定量研究超压泥岩盖层中断裂垂向封闭能力是可行的。