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多年来由压裂液体系造成的聚合物伤害一直是个问题。聚合物造成的损害导致裂缝导流能力降低和有效支撑裂缝长度减小。减小聚合物损害的一个方法是减少凝胶用量。从历史上看,研究出的减少聚合物用量的体系遇到了许多问题。减少压裂液体系中聚合物用量的结果是导致压裂液黏度过低而不能够携带足够的支撑剂。对于低渗透气井来说,由于减小了裂缝长度,支撑剂携带效果差造成产量低。由于缺少使压裂液体系达到其最大黏度的合适水源,所以许多低聚合物用量压裂液体系在操作上是不可靠的。除了确定合适水源的操作问题外,对压裂液体系的另一个限制是用液态KCl代替粒状KCl的技术要求。这些问题都限制了低聚合物用量体系在许多地区的使用。与有机金属交联剂有关的剪切敏感性是使用低聚合物用量体系时遇到的问题。与硼酸盐交联体系相比,高管状速度将剪切降解压裂液,降低其支撑剂携带能力。本文将讨论硼酸盐交联压裂液的改进,并以实例说明减少聚合物用量体系的应用和效果。
Polymer damage caused by fracturing fluid systems over the years has been a problem. Damage caused by the polymer results in a reduction of the fracture conductivity and a decrease in the effective support crack length. One way to reduce polymer damage is to reduce the amount of gel. Historically, systems developed to reduce the amount of polymer encountered have encountered many problems. As a result of reducing the amount of polymer in the fracturing fluid system, the fracturing fluid viscosity is too low to carry enough proppant. For low permeability gas wells, low proppant loading results in lower yields due to reduced fracture length. Many low polymer usage fracturing fluid systems are not operationally reliable due to the lack of a suitable source of water to bring the fracturing fluid system to its maximum viscosity. In addition to determining operational issues with suitable sources of water, another limitation to the fracturing fluid system is the replacement of granular KCl with liquid KCl. These problems limit the use of low polymer dosage systems in many areas. Shear sensitivity associated with organometallic crosslinkers is a problem encountered with low polymer dosage systems. In contrast to the borate cross-linking system, high tubular velocities shear the fracturing fluid and reduce its proppant-carrying capacity. This article will discuss the improvement of borate cross-linked fracturing fluids and illustrate the application and effectiveness of the system to reduce the amount of polymer used.