低渗透油田暂堵重复压裂堵剂用量优化与现场试验

暂堵重复压裂是开启天然微裂缝、提高侧向剩余油动用程度的重要手段之一。由于目前施工过程中对堵剂用量没有具体优化,多凭经验确定,往往造成暂堵升压幅度小。为了提高鄂尔多斯盆地暂堵重复压裂的可控性,针对低渗透油田天然微裂缝发育、2向水平主应力差较小的特点,在分析暂堵压裂过程中存在的突出问题后进行了暂堵剂的筛选,以减少堵剂残留给储层渗透率带来的伤害;依据巴布库克关于支撑剂在裂缝中的沉降规律,模拟暂堵重复压裂过程中人工裂缝内的暂堵压差,实现升压造侧向缝,并重新认识了暂堵压裂成败的关键影响因素和影响规律;利用三维压裂软件求取缝高、缝宽等关键参数,优化了暂堵剂的实际用量,现场试验中暂堵升压明显。该方法进一步完善了低渗透油田裂缝暂堵压裂优化设计方法,对现场施工具有一定的指导作用。

Usage optimization and field test of blocking agent for temporal-blocked re-fracturing in low permeability oilfield

Temporal-blocked re-fracturing is one of the important means to open the natural micro-fractures and improve the lateral producing extent of the remaining oil. But the rate of success is low by experience because of the blocking agent dosage without specific optimization in re-fracturing treatment. Aimed at the characteristics of natural fracture development and small two principal stress difference in low permeability oilfield of Ordos Basin, in order to improve the controllability of temporal-blocked re-fracturing, this paper selects the temporary blocking agent that is commonly used after the analysis of the existing problems for the low permeability reservoirs in the process of temporal-blocked re-fracturing, reducing the damage of the blocking agent residue to reservoir. A new method of computing the volume of the temporary blocking agent on the basis of Babcooky theory about the distribution of proppant in vertieal fractures is brought forward to renew the key factors in the temporal-blocked re-fracturing. Combined with 3-D fracturing software, the key parameters such as fracture height and fracture width are calculated and the actual dosage of temporary blocking agents are optimized. The pressure of temporary blocking rises obviously by field test. This method further optimizes the design of temporal-bh）cked re-fracturing for the fracture of low permeability oilfield and has certain guiding role for on-site treatment.