A Pilot Study on Dispersion and Invasion of Light Weight Drilling Fluids on Seabed and their Environmental Impact

Document Type : Research Paper

Authors

1 Petroleum Engineering Research Division, Research Institute of Petroleum Industry

2 Faculty of Marine Sciences & Technologies, Islamic Azad University, Tehran North Branch

Abstract

In this paper, an attempt was made to generally point out the role of drilling fluids in achieving hydrocarbon reservoirs and to investigate the experimental results of the effect of different environmental water flow rates in offshore area on the rate of influence of parameters like particle settlement on the seabed. Drilling fluids are pumped via drill string to the bottom hole and bit nozzles to carry suspending cuttings upward and are then thrown into the sea. This high volume of the removed cuttings will be dispersed in the sea levels and settled in the widespread deep waters. Also, due to limited space and using a platform for drilling several wells this can be even worse. This study investigates the effect of height and discharge rate on the dispersion-invasion of light weight drilling fluids. Considering discharging the fluids which are 45 lb.ft-3 in three conditions, namely top, surface, and subsurface of the sea level, with a respective flow rate of 0.4, 0.1, and 0.05 m.s-1, the results demonstrated that the rate of influence were (15,10,50), (15,5,5), and (20,12,10) respectively. With the dilution of drilling fluid in sea water, drilling fluids approach near sea level and disperse horizontally after 240 seconds. For a drilling fluid with a density of 65 lb.ft-3, the influential depth at flow rates 0.025, 0.05, 0.1, and 0.4 m.s-1 are 50, 45, 50, and 25 cm respectively. If fluids are discharged at the subsurface of sea, their depth influence will be 50 cm at these flow rates after 5, 30, 90 min, and over time according to different flow rates. In addition, it was observed that the slip velocity of drilling fluid particles at a water flow rate of 0.025 m.s-1 decreases; however, at a water flow rate of 0.05 m.s-1, the slip (falling) velocity was 7 cm.s-1.
 

Keywords

References

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Journal of Petroleum Research
Volume 23, Issue 73 - Serial Number 73
July and August 2013
Pages 134-146

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