碳酸盐岩油藏酸压模型研究及应用

现有的酸压设计存在以下问题:压裂液滤失多采用针对均质储层的经典滤失理论，酸液的滤失没有考虑酸蚀蚓孔的影响，酸岩反应模拟中未考虑裂缝高度方向酸液的传质。针对这一问题，在有关酸压模型最新研究成果的基础上，对碳酸盐岩油藏多级酸压设计计算的核心模型作了较为深入的研究，建立了碳酸盐岩油藏多级酸压时压裂液滤失计算模型，给出了模型的解析解；基于碳酸盐岩油藏酸压中酸液的流动反应特性，建立了酸蚀蚓孔的增长模型、酸液在蚓孔内流动反应模型和滤失的酸液在地层中流动模型，提出了便于现场应用的碳酸盐岩油藏酸液滤失计算方法；推导了考虑酸液沿缝长、缝高方向的运移以及酸液在裂缝宽度方向对流扩散的三维流动反应数值计算模型，为碳酸盐岩油藏的酸压设计提供基础理论依据。

Model study of acid fracturing model for carbonate reservoirs

The current acid fracturing design has the problems as follows: the classical leakoff theory for homogeneous reservoirs is mostly used for the leakoff of fracturing fluid, the acidizing fluid does not taken the effect of acid wormhole into account, and the simulation of acid-rock reaction dose not consider the acidizing fluid mass transfer along the fracture height. In accordance with the problems, on the basis of the up-to-date research of acid fracturing models, further study is conducted on the core models for multi-stage acid fracturing design and calculation of carbonate reservoirs. So the model is set up for calculating fracturing fluid leakoff of carbonate reservoirs when multi-state acid fracturing, the analytic solution to the model is presented. Based on the reaction characteristics of acidizing fluid flow, the growth model of acid wormhole, the reaction model of acidizing fluid in wormhole, and the flow model of filtrated acidizing fluid in formations are established. The calculating method of acidizing fluid leakoff favorable for field application is put forward. Considering the migration of acidizing fluid along the fracture length and height and the convective diffusion of acidizing fluid along the fracture width, the numerical model of 3D acidizing fluid flow-reaction is developed. All these provide theoretical basis for acid fracturing design of carbonate reservoirs.