塔河油田碳酸盐岩缝洞型油藏堵水效果地质影响因素

塔河油田主力油藏是受多期岩溶作用叠加改造、多期油气充注形成的碳酸盐岩缝洞型油藏,储集体非均质性极强,油水关系复杂,堵水效果整体较差。通过对塔河油田碳酸盐岩缝洞型油藏堵水效果地质影响因素分析后认为,油井储集体类型和油水分布模式是影响堵水效果最关键的地质因素。由于大型溶洞特别是高角度裂缝的存在,碳酸盐岩缝洞型油藏剩余油分布复杂,且分别易造成工艺上封堵难度大和堵死的现象,堵水效果较差。而裂缝-孔洞型储集体类似砂岩油藏,储层呈"似均质"状,堵水效果相对较好。与储集体类型相对应的似均质型油水关系模式以及表现出来的缓升型、台阶式上升型的含水率上升类型的油井,堵水效果好;同时致密段的存在提高了堵水效果。

Geological factors influencing water shutoff effects of fractured-vuggy carbonate reservoirs in Tahe oilfield

The major reservoirs of Tahe oilfield consist of fractured-vuggy carbonates which underwent multiple stages of karstification and hydrocarbon charging.These reservoirs are of strong heterogeneity,complex oil-water contact and poor water shutoff effect.This study indicates that reservoir types and oil-water distribution patterns are the two key geological factors affecting water shutoff.The remaining oil distribution of the carbonate reservoirs of fractured-vuggy type is quite complicated due to the existence of big solution cavities,especially the high-angle fractures.The big solution cavities can make plugging water diffcult,while the high-angle fractures can easily result in complete shutoff,leading to poor shutoff effects.The fracture-vuggy reservoirs show quasi-homogeneity similar to sandstone reservoirs,thus their water shutoff effects are fair.Oil-water relationship pattern of quasi-homogeneous type corresponding to the reservoir types and wells with slowly-increasing or step-wise increasing water cuts have better water shutoff effects.Moreover,the existence of tight sections also can improve the water shutoff effects.