With current demand for gas at historic peak, any decrease in production due to deposits of scale within tubing is the most troublesome for any E&P company. Statistically 28% of time it is the scale in well that hinders producing it at optimum rate. "Carbonate" and "Sulfate" scales are most common of mineral scales that form in wells. Carbonate scales are generally tackled by wellbore cleanout with acid or by using scale inhibitors to slowdown scale deposition process but none of these solutions solve the problem on permanent basis. Sulfates scales are generally very hard to remove through acid job and usually chemical chelants are used to control sulfate scales.
The major production enhancement challenge faced in well ‘X’ was to permanently mitigate severe scale build up issue in tubing for optimum production performance. This paper presents how these challenges were faced and overcome by using ClearWELL* unit, resulting in stable and continuous production.
A scale study was conducted by OMV laboratory in Vienna to identify the scale build up mechanism and solutions for its mitigation. The study confirmed that minor pressure decrease at formation temperature promoted water transfer into the gas phase, if water rate is low compared to gas rate, this can result in complete evaporation and formation of precipitate leading to scale build up (mainly calcite). To reinstate production, repeated wellbore cleanouts with coiled tubing using diluted HCl (7.50%) were thought to be the temporary solution in fighting CaCO3 scales.
ClearWELL unit was commissioned at well ‘X’ x-mas tree, which is currently under pilot testing. It is an electromagnetic device which continuously generates electronic dipole that induces a randomly varying high frequency electric field throughout the entire piping system. The electric field generated by device forces homogeneous crystal formation in suspension rather than on metal surfaces. Scale crystallizes in suspension and is carried away with gas water mixture.
During last 5 months of its pilot testing, results achieved so far are promising. Stable and no lost production added a reasonable value to the producing asset and saved huge revenue loss to the company.