Subsurface Drilling Waste Injection: Real-Time Waste Domain Characterization Using Injection Monitoring and Pressure Interpretation

摘要

Subsurface drilling waste injection has been proven as an environmentally safe and cost-effective alternative for drilling waste disposal in remote and environmentally sensitive areas. This has resulted in the rapid expansion of waste injection operations into major E&P regions throughout the world, and thus, the dramatic increase in total drilling waste volume injected in recent years. Despite the outstanding milestones that have been achieved and the millions of barrels of drilling waste successfully injected, there are significant subsurface risks involved with any waste injection project, such as breach to surface, intersection with near-by wells or natural faults and well plugging. Limited understanding and characterization of those risks could potentially have a significant environmental impact and jeopardize the pre- defined project execution plan. Therefore, continuous injection monitoring and pressure interpretation coupled with a proactive subsurface assurance process is the key to mitigate those risks and ensure environmentally safe and seamless waste injection operations. Complexity of fracturing systems created during multiple waste injections render it imperative to monitor and characterize the waste domain in real time through corresponding pressure behavior interpretation. This paper presents the unique and technically challenging injection monitoring and pressure interpretation experience attained in different waste injection projects in the CIS region, where the in-depth interpretation of fracture behavior and waste domain monitoring helped to minimize subsurface risks and to provide an adequate level of subsurface assurance. Continuous monitoring of injection data and parameters by a group of geo-mechanical experts in close collaboration with the operational team helps to identify and minimize the sub-surface risks and generate appropriate recommendations and mitigation procedures to avoid potential injectivity failures. Currently more than one and a half million barrels of drilling waste have been successfully contained through various waste injection projects in the CIS region.