Development and application of a ZM-2 drilling fluid density adjustment mixing device

作者：Lei Zongming^*; Rong Zhun; Kong Songtao

来源：Natural Gas Industry, 2014, 34(11): 82-87.

DOI：10.3787/j.issn.1000-0976.2014.11.011

• Dynamic method
• Field test
• Flow field simulation
• Killing fluids
• Laboratory test
• Mixing devices
• Nanhai No. 8

High-pressure shallow (gas/water) flow is often hidden in the deepwater seabed, and it is risky to drill down in shallow flow without BOP. At this point, it is no longer applicable to adopt the conventional well killing method of using back pressure generated by wellhead equipment to balance the formation pressure. Based on the analysis of structural characteristics of domestic and foreign multi-phase mixing systems, a ZM-2 drilling fluid density adjustment mixing device was developed according to the principles of dynamic well killing with an independent intellectual property right. The device is mainly composed of a throttle valve, a high-precision electromagnetic flowmeter, a mixer, dumbbell-shaped nozzles, connecting pipes and other components. Fixed on the mixer are three inlets to fill heavy mud, seawater and additives. Opposed jetting is adopted to realize rapid and uniform mixing of fluids with different densities. A laboratory test was conducted to work out the relationship between throttle opening and injection flow rate and establish a linear relationship between killing fluid density and a heavy mud flow. The results of the field test conducted in the Nanhai No. 8 drill ship showed that the mixing device was stable in operation and excellent in mixing performance. The density difference of ingredient mixture could be controlled within 0.05 g/cm3 after the mixture flowed out the mixing chamber of the mixer about 0.3 m, so such high precision could meet the requirement of well killing with a dynamic method.

• 出版日期2014