Optimization of cuttings slurry system for re-injection of oil-based drilling cuttings

Abstract

ABSTRACT Cuttings re-injection technology has become a preferential choice of the treatment of oil-based drilling wastes in offshore oilfields. However, there are relatively few formulation designs and performance tests for re-injection slurry systems. In this study, an oil-based drilling cutting re-injection fluid system was developed. The relationship between the suspension and rheology of the re-injection fluid and time is obtained by using the experimental method of sectional measurement. The laboratory re-injection fluid preparation procedures are introduced in detail. The final optimized cutting slurry has a formula for drilling cuttings content of 15% −35%, guar gum (GG) content of 0.4% as the main additives, and auxiliary additives such as 0.3% fluid loss agent and 0.3% defoamer. The experimental results show that the re-injection fluid has good suspension and rheology. After standing at 60°C for 24 h, the sedimentation density difference is only less than 0.12 g/cm3, and the viscosity is 51–66 mPa·s. The cross-linked structure of the internal molecules of the fluid system remains stable, and the viscosity does not decrease obviously to the increase in time. The overall performance of the optimized re-injection fluid satisfies the requirement of the operator.