新型酸性交联压裂液的研制与应用

DEVELOPMENT AND APPLICATION OF A NEW TYPE OF ACIDIC CROSS-LINKING FRACTURING FLUID

压裂液是水力压裂改造的关键，其主要功能是张开裂缝并沿缝输送支撑剂。目前被广泛应用的压裂液体系为水基植物胶压裂液，具有价廉、优良而且易于处理等优点。它们是以植物胶中的胍胶（香豆胶）及衍生物羟丙基瓜尔胶为稠化剂，以硼酸盐或有机硼（有机锆）为交联剂的体系。体系的交联条件为碱性（pH7．5～12），酸性（pH4～5）条件下无法形成可挑挂的交联冻胶。随着勘探深入，对于一些碱敏性地层的压裂改造，需要考虑碱性液体侵入对地层的伤害问题以及二氧化碳泡沫压裂液体系均需要在酸性条件下交联。通过室内实验，研制出了AC—m酸性交联剂，详细阐述了AC—m酸性交联剂的交联机理，形成了以羟丙基瓜尔胶为增稠剂的酸性冻胶压裂液配方体系，并对配方性能进行了室内评价实验，具有快速交联、耐温能力达110℃、流变性好、酸化和防膨性能好等优点。现场进行了4口井应用试验，在进入地层总液量不变的前提下，比以往提高携砂量20％-30％，扩大了施工规模，并且可满足较高砂比的施工需求。

Fracturing fluid is a key factor in the process of hydraulic fracturing, which can make fractures open and carry proppant along the fractures. At present, hydraulic fracturing of water based vegetable gum is widely used with the characteristic of low price, good property and easy treatment, being system with guar gum （fenugreek gum ） and derivant hydroxypropyl guar gum of vegetable gum as thickening agent and borate or organic salt （ organic zirconium） as cross-linker. Cross-linking condition should be alkalinity （ pH =7.5-12）. Acidity （ pH =4-5 ） cannot form cross-linking gel. During hydraulic fracturing of alkali sensitive formation, it needs considering the damage caused by alkaline fluid invaded into formation and cross-linking provision for fracturing fluid system of CO2 foam. Through laboratory experiment, this paper proposes acidic cross-linker of AC-m, and introduces in detail the cross-linking mechanism, with which a formula system of fracturing fluid of acidic gel taking hydroxypropyl guar gum as thickening agent is formed. Laboratory test aiming at formula performance of the system is performed, which proves its characteristics of instant crosslink, high temperature tolerance （110℃ ） , favorable rheological, high a cidizing quality and anti-swelling property. 4 wells are tested in well site with constant liquid volume injected,which increases sand-carrying capacity by 20%--30%, enlarges operation scale and meets the requirement of high sand proportion.