大港地区千米桥潜山奥陶系古岩溶研究

Study of Ordovician paleokarst in Qianmiqiao buried hill in Dagang oil field, China

印支期—早燕山期,北西—南东向挤压应力场使大港地区千米桥奥陶系再次暴露地表,遭受风化、滤淋、剥失,形成了第二次古岩溶。千米桥潜山奥陶系古岩溶在垂向上分为四个带,水平潜流带溶蚀孔隙最发育,垂直渗流带次之,风化残积带和深部混合带储层不发育。岩溶高地处于地下水渗流带和地下水潜流带,溶蚀作用强烈,储层发育。岩溶斜坡和岩溶洼地为地表水汇集区及地下水排泄区,岩溶作用相对较弱,储层不发育。位于岩溶高地的板深8井—千12 18井区和板深7井—千18 18井区是有利的古岩溶分布区,是有利的储层分布区。

In the Indosinian epoch-early Yanshanian epoch, the Ordovician System in the Qianmiqiao buried hill of the Dagang oil field was exposed on the surface, weathered, leached, denuded and formed the second time paleokarst under the structural stress field compressed from north-south shift from west-north to east-south. The paleokarst in Ordovician is classified into four zones in the vertical direction in Qianmiqiao buried hill. Among them, the solution openings in the horizontal subsurface flow zone are best developed, that in the vertical seepage flow zone secondly developed, and that in the reservoirs of the weathered residual zone and deep mixed zone are undeveloped. The high-land of the karst is located in the seepage flow zone and subsurface flow zone of groundwater, where solution is strong and reservoirs are well developed. The karst depression belongs to the accumulative area of surface water and subdrainage area of subsurface water, the karstification is relatively week, and reservoirs are undeveloped. Well Banshen 8 - Well Qian 12-18 and Well Banshen 7 - Well Qian 18-18 are located in the favorable paleokarst areas and reservoir distribution areas in the highland and roof of the paleokarst.