Abstract
Performance and environmental assurance of cuttings injection programs require monitoring and periodic analysis of injection response. Such programs provide operational oversight and the ability to respond to changes in performance, providing for optimization of operating parameters to minimize potential negative impacts. Cuttings injection was implemented on a remote pad in the Cashiriari Field, located in a nature preserve in Camisea, Peru. CI was recognized as a technically and environmentally acceptable alternative for waste management in a location with extreme environmental sensitivity. Higher than anticipated injection pressures, indicative of regional and local stress regimes, required adjustments in operating parameters and expectations.
Performance was contingent on successful inhibition of reactive clays in and around the target zones. Continuous monitoring of closure pressure and other trends associated with batch injection has made performance predictions possible. Monitoring operations have allowed for performance improvement and/or minimization of potential problems. The operation injected over 212,000 bbls of cuttings on the first pad and continues to be successful on the second pad through careful management of batch attributes and adaptation to operating realities. Assurance derived from such programs provides long term operational viability and social acceptance of cuttings injection as a safe means of waste management.
Introduction
Assurance of a successful and environmentally sound long-term cuttings injection program requires monitoring and periodic analysis of injection performance response [1, 2]. Such a program provides for operational oversight and the ability to identify changes in performance response or trends, thereby providing for modification of operating parameters to optimize performance and minimize the negative impact of unexpected responses [3, 4, and 5]. An implementation of this process was instituted for two remote, pad-drilled sites located in a nature preserve in the Amazonian rainforest of Peru, Figure 1 and Figure 2. The development
of natural gas reserves at Camisea has extreme environmental sensitivity and injection of the generated drill cuttings was recognized as a technically and environmentally acceptable alternative for drilling location waste management. Over the life of both injection sites a total of 570924 bbls of slurry were injected. Cashiriari Pad 1 well, CR1, received a total of 309,976 bbls and the Cashiriari Pad 3 well, CR3, received a total of 260,948 bbls. The main difference between Pad 1 and Pad 3 was volume of waste (water) injected, which was larger for Pad 1. However the volume of cuttings was greater on Pad 3, due to a deeper target
horizon.
A number of issues were encountered in implementing and operating the DCI project at both Cashiriari sites. Higher than anticipated initial injection pressures were indicative of the stress regime of the region and required an adjustment in thinking with respect to operating parameters and performance expectations. Issues regarding Cashiriari Pad 1 have been well documented in two prior papers [6, 7]. The focus of the current paper is Cashiriari Pad 3 event, modifications and best practices.
