Preparation of drag reducing agent and properties of composite osmotic acid based on volume fracturing

Abstract

Based on the inspirations that slickwater volume fracturing can produce and communicate microfractures, acid fracturing is applied to carbonate rocks by using composite osmotic acid with large displacement and low friction. The drag reducing agent P(AM-DMC-DMAM) was synthesized by acrylamide, N,N-dimethylacrylamide and methacryloyloxyethyl trimethylammonium chloride as the main monomer through free radical polymerization. And the structure was characterized by infrared spectroscopy and ¹H NMR. A composite osmotic acid was prepared with drag reducing agents and high-efficiency penetrants as the main agent. The results of the drag reducing and rheological tests show that when the flow rate is 51.70 L/min, the drag reduction rate can reach 70%, and the viscosity of the acid solution after shearing at 170 s⁻¹ and 140 °C for 90 min is 10mPa·s. The results of core permeability and solid damage analysis show that acid has excellent performance on communication to core and its microfractures. The corrosion performance study show that the maximum corrosion rate is 7.05 g/(m²·h), and the pitting factor is around 1.3. The acid etched fracture conductivity is still 4.8μm²·cm when the closing pressure reaches 60.0 MPa.

Keywords:

• Carbonate rocks
• composite osmotic acid
• drag reduction
• performance study
• preparation

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (51604052, 51774062, 51504050), Natural Science Foundation of Chongqing, China (cstc2019jcyj-msxmX0064), Scientific and Technological Key Research Program of Chongqing Municipal Education Commission (KJZD-K201901502), Chongqing Postgraduate Research and Innovation Project of China (CYS20362) and Graduate Science and Technology Innovation Program of Chongqing University of Science and Technology (YKJCX1920504, YKJCX1920506).