塔河老区井周弱势通道暂堵酸压技术

Temporarily plugging and acid-fracturing technology in weak channels near wellbore region in Tahe Oilfield

塔河油田微地震监测表明,最大主应力、天然裂缝、古河道形成酸压裂缝优势延伸方位,而井周受抑制的弱势通道却未动用,极大地影响着酸压效果,为此提出了井周弱势通道暂堵酸压技术。通过对可降解纤维进行基础性能评价,研究了材料的适用性,并优化得到封堵不同宽度裂缝的最优暂堵剂组合。结合实验及现场应用经验确定了选井原则,优化了相应施工参数。结果表明:储层温度下,所选纤维在清水及酸液中的稳定存在时间满足施工要求;优选的暂堵剂组合封堵快、用液量少,且满足承压要求;基于实验及现场经验,确定单井暂堵剂用液量为1.0~1.5 t。施工排量以"初期小、暂堵定、后期大"原则设计,并在暂堵段采取"三层暂堵"模式确保暂堵成功率。文中形成的目标工艺对储层伤害低、风险小、增产效果明显,对塔河油田剩余油的开发具有重要的指导及借鉴意义。

Microseismic monitoring shows that the dominant orientation of fracture extension is formed due to the impact of maximum principal stress, natural fractures, and the paleo-river, which leads to the existence of suppressed weak channels near wellbore region,and greatly affects the acid fracturing effect. The research on temporarily plugging and acid-fracturing technology in weak channels near wellbore region was carried out for the issue. By evaluating the basic plugging performance of new degradable fibers, the applicability of material was judged and the optimum combinations of plugging agents for different fracture width were obtained;combining the experiment and on-spot experience, the principles of well selection were determined and a series of construction parameters were optimized. Results indicate that: the stable existence time of fibers in clear water and acid solution at reservoir temperature meets the construction requirement;the optimum combinations of plugging agents for different fracture width can form plugging quickly with less liquid and meet the pressure requirement;based on the experiment and field experience, the dosage of plugging agent for single well was determined to be 1.0-1.5 t. The construction displacement was designed according to the principle of "small displacement in the early stage, fixed displacement in the middle stage and large displacement in the later stage", and "three-layer temporary plugging" mode is adopted to ensure the success rate of temporary plugging at the temporary plugging stage. The target technology has low damage, low risk and obvious stimulation effect, which has certain guiding significance and reference for the Tahe Oilfield.