Deepwater Well Control - An Important Way Forwards

Leach, Colin; Mounteer, Jim

doi:10.2118/163550-ms

Cited by 6 publications

(1 citation statement)

References 3 publications

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“…To investigate the effect of surface back pressure on peak liquid rate and gas rate during riser gas handling, pressure of 0 to 600 psi was applied on the top of riser for 10 bbls influx with the pump rate of 160 gpm. Similar to the findings of Leach and Mounteer (2013), as shown in Fig. 13 and Fig.…”

Section: Dual Gradient Drilling Riser Gas Handling Studysupporting

confidence: 89%

Mitigating Gas in Riser Rapid Unloading for Deepwater Dual Gradient Well Control

Yuan

Morrell

Sonnemann³

et al. 2016

Day 1 Mon, May 02, 2016

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In deepwater dual gradient wells, if gas comes into the riser, a rapid unloading event may occur if removal of the gas is not carried out properly. Oil based muds present an even greater challenge when compared to water based muds to avoid gas in riser events, because the gas dissolves in the mud and may not be detected until it breaks out inside riser near the surface.A study using a dynamic multiphase flow software simulated a rapid unloading event and determined the gas fraction in the riser annulus and the effect on riser fluid levels. New procedures, such as shut-in the riser or proactively applying surface pressure were simulated to evaluate effectiveness of riser-top equipment to mitigate risks of rapid riser unloading. The effects of gas volume, and mud type (water vs. oil based mud), on water hammer and riser top pressure during the shut-in were analyzed using a simulated case with a riser in 8,000 ft of sea water.The analysis shows there is no significant pressure increase at the moment of rapid unloading in a shut-in well. The simulation results reliability is verified using a field test conducted in 1,200 ft sea water. The simulation results show it is possible to safely manage gas-in-riser events for large gas fractions using available managed pressure drilling and riser gas-handling equipment.It should be possible to safely and efficiently manage events involving even relatively large gas influxes in risers by use of new proposed procedures, which mitigate the rapid unloading and can help industry develop new guidelines for deepwater drilling operations.

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Section: Dual Gradient Drilling Riser Gas Handling Studysupporting

confidence: 89%

Mitigating Gas in Riser Rapid Unloading for Deepwater Dual Gradient Well Control

Yuan

Morrell

Sonnemann³

et al. 2016

Day 1 Mon, May 02, 2016

Self Cite

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Managed Pressure Drilling as Well Control in Deepwater GOM: Challenges to Current Modes of Thinking

Weems¹,

Moore

Leach³

2016

All Days

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Managed Pressure Drilling (MPD) has gained industry acceptance with surface BOP stacks where improved control of downhole pressure has been achieved. The industry is currently beginning to see implementation of MPD systems in deepwater environments where narrower drilling margins make improved pressure control even more important. Despite the evident need for such applications the industry has been slow to fully utilize MPD techniques in deepwater. The question this paper seeks to address is, "What is preventing us from employing the same MPD systems currently being used with surface stacks in a deepwater environment?" This question encourages challenging conventional modes of thinking in the industry concerning risks pertaining to risers and well control when utilizing MPD systems. This paper draws on some of the difficulties, thinking, and achievements when such a system was implemented for drilling a deepwater GOM well. MPD in deepwater involves new equipment, capabilities, and risks. Full utilization of MPD systems in a deepwater environment requires re-thinking several things including primary well control and the conditions to which the riser is exposed.

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Dynamic Simulation of Major Kick for an HP/HT Well in Western China

Zhao

Jia

et al. 2016

Day 2 Tue, November 08, 2016

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As the search for petroleum has moved into the high-pressure/high-temperature (HP/HT) environment, the well control problems have continued to increase in complexity due to the small pressure margins and the large temperature-driven variations of mud properties often seen. Recently in western China, a major kick was encountered while drilling to 7874 m with 16-ppg water-based mud in an HP/HT well. Killing of the well was attempted but was not successful. After that, the drillstring broke near the top of wellbore. As a contingency action, the operator abandoned the plan for further killing and put the well into production through diverting the kick to the production pipeline. Many unknowns, which were unsolvable by conventional perceptions, were still intriguing the operator and might be issues in further drilling operations in this field. These unknowns include: (1) Why was the well pressure constant before the gas reached the wellhead while the well was shut-in for almost 2 days? (2) Where was the gas top during shut-in? (3) Why did the killing attempt fail? (4) What killing parameters should have been used in the killing attempt? To address these unknowns and provide solid guidance for further drilling operations, simulation of the gas kick development and well killing was conducted using a dynamic hydraulic and well control simulator powered by transient multiphase flow model. Through integration of existing well and reservoir data, the dynamic simulation was able to history match the observed wellhead pressure, casing pressure during the shut-in, and killing operations. The simulation showed that the killing pump rate was not adequate to kill this well for the given gas kick in the wellbore. The dynamic simulations successfully revealed the reason for the gas suspension in the wellbore while shut-in, predicted the gas top, and identified the required pumping rate for a success killing. The simulation also disclosed the root cause of the drillstring failure. This case study highlights the importance of dynamic simulation during the well engineering design and before any attempt of well killing to improve chance of success for well control and safety of drilling operations.

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Deepwater Well Control - An Important Way Forwards

Cited by 6 publications

References 3 publications

Mitigating Gas in Riser Rapid Unloading for Deepwater Dual Gradient Well Control

Mitigating Gas in Riser Rapid Unloading for Deepwater Dual Gradient Well Control

Managed Pressure Drilling as Well Control in Deepwater GOM: Challenges to Current Modes of Thinking

Dynamic Simulation of Major Kick for an HP/HT Well in Western China

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