礁灰岩油藏微粒过饱和充填技术机理及创新实践

南海东部地区流花油藏为礁灰岩油藏,按其内部结构特点,包括基质、裂缝及溶孔三重介质。油井含水上升速度快,各项常规增产技术均无明显效果。该油田在“微粒环空充填技术”的基础上,在业内首次创造性提出并尝试了“微粒过饱和充填技术”,已实施的3口井均取得明显效果,在保证产能的同时,含水率比邻井低30%以上,且含水上升速度慢,预测该技术单井增油5×10⁴ m³。但由于礁灰岩油藏地质油藏条件的复杂性,该技术应用的作用机理多有争论。因此,综合裂缝特征、渗流力学、油藏工程、完井工艺、数值模拟等研究,进行了礁灰岩油藏“微粒过饱和充填技术”的作用机理研究,认为起到“控水、堵缝、储层改造”三重作用,早期以储层改造为主、一定程度起到堵缝作用,相对高压充填微颗粒对近井储层起到扩张微裂缝、沟通更多基质储层、增大波及范围,后期以控水为主。该研究将指导本油田对微粒过饱和充填的后续应用,以及对其它裂缝性礁灰岩油田或者底水砂岩油田的控水增产具有较强的指导

The Mechanisms and Innovative Applications of Over-saturated Particles Well Completion Technique in Limestone Reservoir

Liuhua reservoir in the east of South China Sea is a limestone reservoir, with a three-medium porous system, including matrix, fracture and pore. The water cut of oil wells goes up very fast. Various methods have been tried to solve this problem, but few effects have been achieved very. Based on the common particles filling technique, an over-saturated continuous pack-off technique is proposed and three wells have achieved obvious results. The water cut was 30% lower than adjacent wells and goes up much slower, the estimated ultimate recovery is 50 thousand m₃ more than designed. Due to the complexity of the geological and reservoir conditions, the mechanisms of this technique is controversial. This paper, based on the study of fractures, porous flow features, reservoir engineering method, well completion and reservoir simulation, studies the mechanisms of over-saturated particles, which are water control, fracture plug and formation remolding. At early stages, the main mechanism is formation remolding and fracture plug, over-saturated continuous pack-off injection amplifies the micro-fractures and connect the matrix. At later stages, water control is the main mechanism. This study will guide the further application of this technique to limestone reservoir and other bottom-water driven sandstone reservoirs.