Design and Experimental Research of a Wellhead Overflow Monitoring System for Open-Circuit Drilling of Natural Gas Hydrate

Abstract

Natural gas hydrate is easy to decompose and leak due to the changes in temperature and pressure during drilling, which causes safety accidents. Early monitoring of wellhead overflow is a practical and effective measure to prevent overflow blowouts and other accidents. Herein, a wellhead methane monitoring system for the open-circuit drilling of marine natural gas was designed. The system consisted of an overwater acoustic reception part and an underwater self-contained methane monitoring part, matching the construction environment of marine natural gas hydrate exploitation. Compared with the existing gas logging technology (measurement while drilling), the monitoring and early warning of wellhead methane content were realized at all stages of drilling, casing running, cementing, completion and fracturing in the process of natural gas hydrate exploitation. System communication and data acquisition tests were completed at different water depths through sea trials, which verified the effectiveness of the system design. The research results provide important theoretical and technical implications for promoting the development of early spill monitoring technology at the wellhead of open-circuit drilling for marine gas hydrates.

Safety Risk Assessment of Reservoir Dam Structure: An Empirical Study in China

“…The construction of reservoir dams is a significant event in the transformation of nature by man, nevertheless, we have not tamed nature. In the past decades, safety accidents have been worldwide, such as reservoir overflow, dam landslides, and dam collapse [1][2][3].…”

Quantitative Analysis of the Stability of a Mud-Return Circulation System in a Riserless Mud-Recovery Drilling System

“…The applications of the riser system are mostly limited to oil and gas drilling [5][6][7][8] because of its high cost and complex structure and the demand for large-tonnage drill platforms or drillships. In open-circuit drilling conditions, the direct discharge of mud into the sea induces marine environmental pollution and involves a substantial consumption of mud [9]. To address the mud-handling and recovery challenges in a downhole operation, riserless mud recovery (RMR) technology has been widely adopted in deepwater oil production.…”