惠民凹陷商河油田商一區河口壩儲層構型精細剖析

國景星+宋曉倩+王思文+郭云龍+彭雪還

摘要：惠民凹陷商河油田商一區油氣儲層經過近40年的勘探開發，挖潛難度越來越大。為了進一步搞清該區剩余油分布規律，充分利用研究區豐富的巖芯、測井等資料，對沙二下亞段三、四砂組河口壩儲層的垂向級次劃分、單一河口壩識別及發育特征、垂向演化規律等開展精細研究。結果表明：河口壩儲層發育5級構型界面，其中五、四級界面的成因類型分別為洪泛泥巖、砂體披覆泥巖，三級界面的成因主要為物性差異沉積、成巖鈣質砂巖，并進一步細分為泥質夾層、物性夾層和鈣質夾層3類；三級界面中泥質夾層的橫向連續性好于物性夾層和鈣質夾層，延伸距離為300～800 m，沿河口壩進積方向，在坡折帶處夾層傾角最大可達8°，至湖盆內部夾層傾角一般小于2°，沿垂直于砂體推進方向，夾層傾角一般低于1.5°；儲層頂面高程差異、壩間沉積、壩緣側向交錯疊置、曲線形態及砂體沉積厚度差異是單一河口壩側向邊界的4種識別標志；基準面的升降變化控制了沉積砂體間疊置關系，決定了河口壩砂體的沉積厚度及儲層物性特征。該研究成果對于指導商河油田及相似油田開展后期剩余油分布預測具有借鑒意義。

關鍵詞：河口壩；儲層；構型；界面級次；垂向演化；沙二段；商河油田；惠民凹陷

中圖分類號：P618.13；TE122.2 文獻標志碼：A

Abstract： After nearly 40 years exploration， the development of petroleum reservoir in Shangyi block of Shanghe oilfield， Huimin sag becomes much more difficult. In order to find the distribution of remaining oil， based on the abundant core and well logging data， the mouth bar reservoir in the third and the fourth sand groups of the second member of Shahejie Formation was analyzed for many aspects， including the grading system of architecture interfaces， the identification and characteristics of a single mouth bar and the vertical evolution law. The results show that the mouth bar reservoir can be classified into 5 grades architecture interfaces； the origin types of the fifth and fourth architecture interfaces are flood shale and argillaceous layers， respectively； the origin types of the third architecture interface are sedimentary with poor physical properties and diagenetic calcareous sandstone， and can be further subdivided into shale interlayer， calcareous interlayer and transitional interlayer； the shale interlayer has more lateral continuity than the calcareous and transitional interlayers in the third architecture interface， and can extend for 300-800 m； along the progradation direction of mouth bar， the dip angle of interface in the slope break belt can up to 8°， while the dip angle is less than 2° in the flat terrain； along the vertical provenance direction of sandbody， the dip angle of interface is generally below 1.5°； four identification marks recognizing lateral boundary of single mouth bar include that the top surface altitude difference of reservoir， the appearance of interval zone of mouth bar deposits， the fringe of two mouth bars overlapping each other and the existing difference from curves and deposition thickness of sandbody； the fluctuation of base level controls the superimposed relationship of sandbody， and determines the deposition thickness of mouth bar sandbody and the physical characteristics of reservoir. This results have an important significance in guiding prediction of the remaining oils distribution in Shanghe oilfield and other similar oilfields.