Abstract
Coiled Tubing (CT) is extensively used in oil industry to clean the wellbore to increase the productivity of oil/gas well by removing the fill/sand downhole. Well cleanup operation for low bottom hole pressure is problematic and common cleanout fluids are not effective as a circulation fluid due to severe pressure losses and low suspension capability. The use of foam as cleaning agent has become more popular due to its low density and high viscosity. The objective of this paper is to investigate the factor effecting on fill concentration and pressure loss during horizontal wellbore cleanup operation at different CT/Annulus diameter ratios using Herschel Buckley viscosity model. Results showed that foam quality has the significantly high effect on fill concentration as compared to foam velocity. It is noticed that diameter ratio has high effect on particle removal when foam quality is 70%. Surprisingly, it is found that the effect of diameter ratio on fill concentration decreases when foam quality is 90%.
Highlights
IntroductionFill (sand and fine) material left in the cased annulus reduces the production of wellbore
Fill material left in the cased annulus reduces the production of wellbore
In the forward circulation mode, Cleaning fluid is pumped in the tubing and mixture of fill and foam is circulated back through cased annulus
Summary
Fill (sand and fine) material left in the cased annulus reduces the production of wellbore. Coil Tubing has two circulation modes to remove solid particles, namely the forward and reverse circulation modes. In the forward circulation mode, Cleaning fluid is pumped in the tubing and mixture of fill and foam is circulated back through cased annulus. Reverse circulation is carried out by injecting fluid from cased annulus and circulated back through coiled tubing. Solid particles transport is problematic in horizontal wellbore [2]. The velocity of circulation fluid in the annulus is kept greater than the settling velocity of the particle. This is to ensure that the circulation fluid has higher buoyancy force than the gravity force of solid particles. Study is forwarded to analyze the fill removal with foam along horizontal well
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