First Successful Cuttings Reinjection CRI Operation in Ecuador: An Alternative to Help Minimize the Environmental Impact in a Protected Area

摘要

This paper discusses a technology for waste management and disposal through cuttings reinjection (CRI). The fully integrated process was successfully applied in the Ecuador Apaika-Nenke field, which is an area with significant oil potential located in the heart of a protected biodiverse zone. The advantage of the applied process, from candidate selection screening to the detailed implementation phase, represents a permanent drilling solution in environmentally sensitive areas. This paper presents a case study of CRI in an Apaika injection well. The well was chosen based on feasibility tests and previous injectivity test results, making it the first drilled waste reinjector well in Ecuador supported by best practices. This paper describes injection equipment used for the slurry process and injection into the formation, waste collection and transportation from the rig site to the CRI facilities, slurrification process describing how the cuttings are treated for reinjection, injection parameters given by the feasibility study, and pressure response to injection explaining how the formation will react in time to the slurry injection. Each slurry injection was performed in 12-hour cycles instead of continuous injection, allowing the formation to reach pseudoequilibrium stages while the cuttings migrated within the selected structure through fracturing conduits. From June 2014 through December 2015, 209,000 bbl of slurry from 11 drilled wells were injected into the disposal well. All the waste fluids (dewatering water, cutting pits rainwater, and rig wash) were used for the preparation of injection slurry, reducing chemical use for the dewatering process. The well was also used for disposal of produced water with more than 400,000 bbl injected. The cyclic injections were conducted in three stages: preflush, post-flush, and slurry injection pumping to displace the entire tubing volume and minimize well plugging risks. During the first stage, wellhead pressure and slurry properties were monitored to help establish accurate injection parameters. No significant changes were observed in terms of pressure performance at a maximum pressure differential of 2,000 psi during the three stages. The first CRI met all expectations of not leaving any cutting on surface. All the cuttings and drilling waste from the Apaika- Nenke pads were reinjected without any operational inconvenience. For future wells, deforestation will not be necessary for new cutting pits in this sensitive area, helping minimize the environmental impact and addressing social challenges and inherent risk present within the oil industry. The application of CRI in the Apaika-Nenke field demonstrated that drilling in a sensitive area could be performed with high environmental standards and in compliance with local environmental laws with excellent results.