Advanced Analysis Identifies Greater Efficiency for Testing BOPs in Deep Water

摘要

Pressure testing blowout preventers (BOPs) with synthetic-based mud (SBM) requires lengthy testing times resulting from pressure/ volume/temperature (PVT) influences associated with SBM. PVT influences are especially pronounced in deep water and high-pressure test environments. A project was initiated in an effort to better understand the mechanics that transpired during BOP testing. The primary objective was to demonstrate that the pressure decline was quantified by the fluid-PVT behavior, mechanical influences and thermodynamics of pressurization, and subsequent cool down. The secondary objective was to demonstrate that the pressure decline resulting from a leak could be reliably and efficiently detected with high-resolution pressure data. It was theorized that the gradual decay of pressure during the shut-in phase was a result of the heat added to the system during pressurization. To pursue this investigation, real-time PVT data were gathered at the cementing-unit (CU) suction and discharge while testing the BOP. In addition, pressure/temperature (P/T) gauges were placed in the drillstring—one at the drill floor, one at the midpoint between the drill floor and the BOP, and one above the BOP stack. The gauges confirmed significant heat up as the system was pressured up for each test. The pressure decreased as the system cooled back toward the ambient temperature. Modeling techniques were developed to understand the system response. This paper presents salient aspects of data acquisition, data interpretation, and modeling techniques. Results demonstrate the potential to significantly impact the industry, with respect to safety, time, and costs for BOP testing.