利用斷層巖泥質含量判斷斷層垂向封閉性的方法及其應用

付廣+胡欣蕾

摘 要：為了簡便地判斷斷層垂向封閉性，在斷層垂向封閉機理及影響因素研究的基礎上，通過比較斷層巖排替壓力與下伏儲層巖石排替壓力的相對大小，建立了一套利用斷層巖泥質含量判斷斷層垂向封閉性的方法，并將其應用于渤海灣盆地南堡凹陷南堡5號構造f1、f2、f3、f4、f5等5條斷裂在東二段泥巖蓋層內的垂向封閉性研究中。結果表明：f1、f2、f4等3條斷裂斷層巖泥質含量均大于其在東二段泥巖蓋層內垂向封閉所需最小的泥質含量，斷層表現為垂向封閉；但f1斷裂位于南堡凹陷沙三段和沙一段—東三段烴源巖分布范圍之外，無油氣供給，f2斷裂受斷層與蓋層配置關系的影響，油氣沿斷裂向上運移，從而無油氣聚集；f3、f5兩條斷裂斷層巖泥質含量均小于其在東二段泥巖蓋層內垂向封閉所需最小的泥質含量，斷層表現為垂向開啟，即使斷裂溝通了烴源巖與儲層，油氣也將穿過蓋層繼續向上運移，不利于油氣富集。這一評價結果與南堡凹陷南堡5號構造東二段下部已發現的油氣分布有著較好的吻合關系，表明該方法用于簡便地判斷斷層垂向封閉性是可行的。

關鍵詞：垂向封閉性；斷層；泥質含量；壓實成巖時間；泥巖蓋層；烴源巖；南堡凹陷

中圖分類號：P618.13；TE122 文獻標志碼：A

文章編號：1672-6561（2016）05-0660-08

Abstract： In order to judge the fault vertical sealing ability simply， based on the mechanism and influence factors of fault vertical sealing， the displacement pressures of fault-rock and underlying reservoir rock were compared， and a set of convenient prediction method of fault vertical sealing ability by using the mudstone content of fault-rock was established， and then the method was applied to study the vertical sealing ability of faults f1， f2， f3， f4， f5 in mudstone caprock of the second member of Dongying Formation of No.5 structure of Nanpu depression，

Bohai Bay Basin. The results show that the mudstone contents of fault-rock of faults f1， f2， f4 are larger than the minimum of mudstone content required by vertical sealing of the three faults in mudstone caprock of the second member of Dongying Formation， so they are sealed in vertical； while the fault f1 is located outside the distribution range of source rocks from the third member of Shahejie Formation and the first member of Shahejie Formation-the third member of Dongying Formation，and the fault f2 effected by the configuration of fault and caprock， petroleum migrates along the fault， so that there is no petroleum accumulation whether the faults are sealed or not； the mudstone contents of fault-rock of faults f3， f5 are lower than the minimum of mudstone contents required by vertical sealing of the two faults in mudstone caprock of the second member of Dongying Formation， so they are open in vertical； though the faults f3， f5 connect the source rock and reservoir， petroleum would move upward through the caprock， and it is not favorable for petroleum accumulation. The evaluation has a good relation with currently discovered petroleum distribution underneath the second member of Dongying Formation of No.5 structure of Nanpu Depression， so that the method is favorable to simply judge the fault vertical sealing ability.