Subsurface Drilling Waste Injection: Challenges, Recent Advances and Cases Studies

Abstract

Drilling waste generated during development of oil and gas offshore and onshore fields are required to be disposed of in a responsible and environmentally friendly manner. The remoteness of such environments, coupled with the ever-tightening environmental regulations and then green operation initiatives of operators, can create significant economical, logistical and regulatory challenges. The subsurface drilling cuttings reinjection becomes the preferred option allowing oil and gas operators to achieve zero discharge which can meet the most stringent environmental standards. To prevent all possible injection issues that were experienced earlier in the industry globally (early 1990's), a novel "design, execute, evaluate approach was introduced, this enables us to deliver reliable, single sourced start to finish solutions Subsurface drilling waste injection has been and continues to be used on several offshore projects where many millions of barrels of waste have been injected in a single well. This has been achieved through the engineering approach "design, execute, evaluate". The design study assesses the subsurface strata and identifies suitable injection zones, with a focus on waste containment assurance. The execution and evaluation phase begins with an initial injectivity test to calibrate all the reinjection modelling completed so far, we then implement real time injections surveillance including advanced pressure analysis as a risk control tool. The key focus is to analyze, identify, and recommend necessary adjustments during injections to prevent injection failure. The studied cases have been operated successfully since their start to date. No injectivity issues have been experienced during drilling waste fluids injections. Several on-time interventions have been made to proactively prevent the well becoming plugged and maintaining surface injection pressures within normal ranges. Recent advances of Real-time data streaming have made big step change improvement in the data delivery process, monitoring pressure analysis. It creates a direct link between the wellsite and worldwide multidisciplinary technical expertise and provides visualization capability at anytime and anywhere to all personnel involved in the project. This step change in monitoring drilling cuttings reinjection operations provides truly "Acquisition to Answer" integrated solution, mitigates the injection risks and enhances the intrinsic value of drilling cuttings reinjection on offshore development projects. This paper shares the experience and the success of subsurface drilling cuttings reinjection where wastes are injected for final and responsible disposal. The offshore field cases are presented to illustrate the value of the recent technological advances along with best practice guidelines and recommendations for safe and economical disposal of drilling waste fluids to achieve true zero discharge results.