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就压裂液携带支撑剂能力问题而言,绝大部分注意力和经费开支一直集中于压裂液的性能方面。低黏压裂液在有些情况下是具有成本效益的,但由于其携带支撑剂能力较差,要获得较长、更为有效的支撑缝长较困难。影响携带支撑剂能力的因素有好几个,而其中最易忽略的一个因素就是支撑剂密度。根据Stoke定律计算,尺寸大小同样为20/40目条件下,密度为1.25g/cm3的支撑剂在液体中的最终沉降速度比白渥太华砂低4倍。计算机模拟和应用实例都说明:低密度支撑剂产层覆盖性好;使用低密度支撑剂进行水力压裂产生的支撑裂缝长。美国东北部Appalachian盆地低渗砂岩气田为了解决成本投入与增加生产之间的矛盾、实现低成本开发,自2003年以来在压裂作业中应用了低密度(1.25g/cm3)支撑剂(主要使用淡水和低密度稠化水压裂液体系),应用地层包括UpperDevonian(上泥盆纪)砂岩、Devonian页岩和SilurianMedina(志留纪麦迪纳统)砂岩,应用区域包括纽约州、宾夕法尼亚州、俄亥俄州、佛吉尼亚州,处理井次超过300(其中2003年7月至2004年7月期间超过40井次)。4个州的现场应用实例说明了低密度支撑剂压裂的短期和长期生产回报,证实了这种新技术的应用可行性;其中一个使用低密度支撑剂和砂的泡沫压裂实例经示踪剂测井说明,砂沉降到了产层以下,而低密度支撑剂则充填在产层中。
As far as the ability of fracturing fluids to carry proppant is concerned, much of the attention and funding has been focused on the performance of fracturing fluids. Low-pressure fracturing fluids are cost-effective in some cases, but due to their poor ability to carry proppants, it is more difficult to obtain longer, more effective support seam length. There are several factors that affect the ability to carry proppant. One of the most overlooked factors is proppant density. According to Stoke’s Law, the proppant at a density of 1.25 g / cm3 also has a final settling velocity in liquid of 4 times lower than that of white Ottawa sand in the same 20/40 mesh size. Both computer simulations and application examples show that low-density proppant lay-up is good and that the support fractures produced by hydraulic fracturing with low-density proppant are long. Low-permeability (1.25 g / cm3) proppant (1.25 g / cm3) proppant has been used in fracturing operations since 2003 in order to solve the conflict between cost-input and increase production for low-cost sandstone gas fields in the Appalachian Basin in the northeastern United States Freshwater, and low density, dense water fracturing fluid systems), the application strata include the Upper Devonian sandstone, the Devonian shale, and the Silurian Medina sandstone. Applications include New York, Pennsylvania, Ohio State, Virginia, processing wells more than 300 (of which from July 2003 to July 2004 more than 40 wells). Field application examples from 4 states illustrate the short-term and long-term production returns of low-density proppant fracturing, confirming the viability of this new technology; one of the examples of foam fracturing using low-density proppants and sand was traced Logging shows that sand settles below the pay zone, while low density proppants fill the pay zone.