The Development and Performance of a New Type of Environment Friendly None-Flowback Retarded Acid

Acidizing is an important measure to increase production and injection in oil and water wells. Mud acid (hydrochloric + hydrofluoric) is usually used as acidizing fluid in sandstone reservoir. However, there are some problems such as too fast reaction of acid-rock, secondary deposition of residual acid and metal ions, formation pollution and residual acid need to flow back. A new type of retarded acid system is synthesized by experiments, which is mainly composed of isopropyl phosphate polymer and fluorine. Isopropelphosphoric polymer is synthesized from phosphorus trichloride, acetone and other materials, and then polymerized with acrylic under the action of initiator to form isopropelphoric acrylic copolymer. The 1H-NMR and the 31P-NMR are adopted to detect and analyze the position and connection mode of hydrogen and phosphorus in the molecular skeleton. The results show that the molecular structure of the synthesized retarded acid contains isopropelphosphoric-acrylic copolymer and polyisopropelphosphoric. Through the evaluation of corrosion performance and scale inhibition performance, it is further verified that the corrosion inhibition performance of the acid system can release hydrogen ions slowly by multistage ionization and inhibit the secondary precipitation. The synthesis process of a new tape of environment friendly none-flowback retarded (EFNR) acid liquid is formed through experimental research. The H+of the molecular structure of the synthesized retarded acid has a multi-stage characteristic of ionization. The carboxylic group and phosphoric group can complex Ca2+ and Mg2+ plasma, and the residual acid does not need to flow back.