New Closed Blender Reduces Footprint, Gasification of CO2in Waterless Fracturing

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 19770, “Design, Optimization, and Application of a Closed Blender for CO2 Waterless Fracturing,” by Qinghai Yang, Siwei Meng, and Chuan Yu, PetroChina, et al., prepared for the 2020 International Petroleum Technology Conference, Dhahran, Saudi Arabia, 13-15 January. The paper has not been peer reviewed. Copyright 2020 International Petroleum Technology Conference. Reproduced by permission. Carbon dioxide (CO2) waterless fracturing uses liquid CO2 to replace water as the fracturing fluid in reservoir stimulation. The continuity and reliability of the blender are key factors determining performance of the operation. The complete paper proposes a novel closed blender that uses a vertical, rather than horizontal, tanker. This modification can reduce the footprint and effectively suppress CO2 gasification. The field practice suggests that the developed closed blender combines the advantages of both vertical and horizontal blenders and ensures successful implementation of CO2 waterless fracturing operations. Introduction The CO2 waterless fracturing process, as an alternative technology for developing unconventional reservoirs, greatly reduces consumption of water resources in the development of unconventional resources. In addition, compared with traditional fracturing measures, this technology has the advantages of low reservoir damage, complex artificial fractures, good energy-storage effect, and a high degree of recovery because of the unique physical and chemical properties of CO2. The CO2 waterless fracturing process requires the following equipment: CO2 tank trucks, booster pump trucks, sand blenders, high-pressure pump trucks, and low-and high-pressure manifolds. The blender acts as the core equipment for dry fracturing of liquid CO2, its main function to mix CO2 with proppant. It then feeds the mixed sand fluid to the fracturing pump truck for CO2 water-less fracturing. In the fracturing process, CO2 on the ground is required to be under low temperature and high pressure continuously to maintain its liquefaction. In addition, CO2 fluid has characteristics of low viscosity, high friction resistance, corrosiveness, and poor lubrication. Compared with traditional hydraulic fracturing processes, the sand blender for CO2 waterless fracturing has specific requirements. Components of the Closed Blender Drawing lessons from design of internationally available closed blenders for CO2 waterless fracturing, the authors have developed independently a new generation of closed blender, mainly composed of a sand tanker, a sand-mixing system, a blender manifold (a discharge manifold and a suction manifold), a chemical-addition system, a hydraulic system, an electronic control system, and a data-acquisition system (Fig. 1).