水平气井酸化后产能研究新方法

A new method to study the productivity of horizontal gas well after acidizing

水平井酸化工艺已在气田开发过程中广泛应用,但由于水平井渗流模式以及井筒附近污染方式的特殊性,酸化后地层渗流将变得更加复杂,因而酸化后的产能研究显得至关重要。以水平井周围污染带以及酸化带的非均匀分布为基础,将水平井酸化后井筒附近复合区域划分为若干个均质区域,利用相似流动替换法得到一个水平井酸化后表皮因子计算的新方法,同时考虑井筒压降,建立了水平井酸化后地层渗流与井筒管流的耦合模型。实例分析表明,酸化后水平井产量大大提高,且随着气层厚度、酸化带渗透率以及酸液作用距离的增大,增产倍比逐渐增大,而随着污染带渗透率以及泥浆浸入半径的增大,增产倍比则逐渐减小。

The technology of horizontal well acidizing had been widely used in developing the gas field, but because of the particularity of flow pattern of horizontal well and damage mode near the wellbore, the fluid seepage in formation will become more and more complex after acidizing, so the study on productivity after acidizing will be of great importance.Based on the non-uniform distribution of damage zone and acidizing zone near the horizontal wellbore, this paper divided the composition area near the wellbore into several homogeneous regions, used the method of displacement between two similar flow modes to get a new method to calculate the skin factor of horizontal well after acidizing,considered the pressure drop in the wellbore, and coupled the wellbore conduit flow and formation seepage. Case study shows that the productivity of horizontal well was greatly increased after acidizing, meanwhile, as the increasing of gas reservoir thickness, permeability of acidizing zone and the distance of acid-rock reaction, the production-increasing ratio also increases, but as the increasing of permeability of damage zone and distance of mud immersion, the productionincreasing ratio decreases.