酸蚀蚓孔参数对油井酸化增产效果的影响规律研究

STUDY ON THE IMPACT OF WORMHOLE PARAMETERS ON WELL PRODUCTIVITY IN CARBONATE ACIDIZING

碳酸盐岩基质酸化过程中形成的蚓孔对增产效果有明显影响,分析蚓孔参数及对产量的影响规律可以为酸化优化设计提供依据。中东某油田基质孔隙型碳酸盐岩储层,孔隙度、渗透率较高,钻、完井过程中造成地层污染,降低了油井产能,基质酸化是这类地层解堵、增产的常用手段。针对中东孔隙型碳酸盐岩储层特点,运用油藏数值模拟方法,在单井径向模型基础上研究了酸蚀蚓孔参数对酸化增产效果的影响规律。研究表明,蚓孔长度对增产效果影响最大,当蚓孔穿过伤害带后,产能增幅随蚓孔长度增加而减弱;蚓孔数量对增产效果影响较明显,但蚓孔数量大于3条后影响不明显,径向条件下的酸蚀蚓孔扩展模拟表明,酸化改造形成的蚓孔基本在3条以上;室内实验观测到蚓孔为岩心级蚓孔,蚓孔直径对产能无明显影响。该研究成果可以为碳酸盐岩酸化优化设计提供依据。

Wormholes generated in the process of carbonate reservoir acidizing has obvious influence on well stimulation.Analyzing the influence of wormhole parameters on well productivity can proved basis for acidizing optimization designs. Drilling and completion inevitably cause damage to reservoirs. For Mideast carbonate reservoirs with relative high porosity and permeability,acidizing is a common way to remove the damage and restore well productivity. Taking a Mideast carbonate well as an example,the influence laws of wormhole parameters on stimulation performance were studied based on a single-well radial model by using reservoir numerical simulation. The study results showed that wormhole length is the main factor influencing well stimulation performance. When the wormholes pass through the damage area,the productivity reduced with the wormhole length increase. The number of wormholes has notable influence on well productivity, but when wormhole numbers are beyond three,the effect is negligible. Wormhole propagation simulations by a radial wormholing model showed that the number of wormholes in matrix acidizing was nearly over three,and the wormhole size observed in laboratory experiments has negligible effect on productivity.