Abstract: Well-developed burial dissolution was found in Yijianfang Formation limestone of Tahe Oilfield.The burial dissolution pores are very important reservoir space for oil-gas in the southern slope of Tahe Oilfield.According to the shape of dissolution pores and the source of dissolving fluids,the burial dissolution can be sub-divided into two types including self-sourced dissolution and foreign-sourced dissolution.The aggressive components for the self-sourced dissolution include organic acids,CO₂ and H₂S derived from thermal maturation of organic matters preserved in the limestone.The self-sourced dissolution is generally weak,because there is a little amount of organic matters and limited aggressive components in the limestone.Consequently,the self-sourced dissolution can only create some small,rounded and isolated dissolution pores at the position where the organic matters were preserved.The aggressive components for the foreign-sourced dissolution include organic acids,CO₂ and H₂S,which were derived from organic matters in hydrocarbon source rocks.The aggressive components mixed with oil/gas-bearing fluids migrated into the limestone along faults,fractures,unconformity surfaces and stylolites from hydrocarbon source rocks.Some relatively large and connected pores were generally formed in the foreign-sourced dissolution.The models for the two types of dissolution were proposed.

Key words: Tahe Oilfield, Ordovician, limestone, burial dissolution, dissolution pores

摘要： 塔河油田奥陶系一间房组灰岩具有典型的埋藏溶蚀特征,埋藏溶蚀形成的次生溶蚀孔隙是塔河油田南部斜坡地区重要的油气储集空间。根据溶蚀孔的形态和溶蚀流体的来源,将埋藏溶蚀作用进一步划分为自源溶蚀作用和他源溶蚀作用两种类型。自源溶蚀作用的溶蚀流体来自灰岩内部,其侵蚀性成分为灰岩本身所含的有机质热成熟作用所释放出来的有机酸、CO₂、H₂S等酸性物质。由于灰岩自身所含的有机质数量少,生成的酸性物质也非常有限,所以自源溶蚀作用非常弱,只能在有机质所在位置溶蚀产生一些微小的、近圆形的、彼此孤立的溶蚀孔,是一种原位的溶蚀作用。他源溶蚀作用的溶蚀流体来自灰岩之外的烃源岩,其侵蚀性成分为烃源岩中的有机质所产生的有机酸、CO₂、H₂S等酸性物质。这些物质随含油气流体沿着断裂、裂缝、不整合面、缝合线等通道运移而来。他源溶蚀作用形成相对较大的溶蚀孔隙,且孔隙之间连通性好。最后给出了这两种埋藏溶蚀作用的发育模式。

关键词: 塔河油田, 奥陶系, 灰岩, 埋藏溶蚀作用, 溶蚀孔隙