Scale deposition, either in the formation, well bore or in the production facilities is a challenging problem in the petroleum industry.

Scale problems are generally associated with the deposition of inorganic minerals, such as calcium carbonate (CaCO3) and sulfates of calcium, strontium and barium. Downhole mineral scaling is either a product of self-scaling of the formation water (FW), (carbonate scale associated with changes in pressure and/or pH) or the mixing of incompatible waters (FW and injection water) with elements of other wellbore fluids or other minerals. The cost of scale buildup can be high, both in terms of deferred production and necessary remedial treatments.

Depending on the nature of the scale and the fluid composition, the deposition can take place within the reservoir, near the wellbore perforation tunnels which causes formation damage, or in production facilities subsurface and on surface with severe operational problems.

The Cased Hole Gamma Ray measurement has been proven quite effective to detect the presence of scale, due to radioactive content proven by the Scale XEM/EDAC analysis. The Scale solubility analysis has proven more than 95% of the sample, are soluble in 10%-HCl based acid.

Finally, the two case studies of Miano field have brought a new game changer for operations, to enhance the gas production. It is based on historical well observation, since no water production had been observed at the surface in one of the case study, so Scale was not considered to cause the production decline. Therefore the method of Cased Hole Gamma Ray measurement can be in some cases the only indication of scale build-up if other indicators are missing. Furthermore it’s also an effective method to prove scale build-up inside perforations if hole is fully accessible.

This paper describes the buildup of scale, its detection and its successful removal with coiled tubing in high temperature gas wells of Miano Field. Furthermore it will show some lab results, the execution and evaluation the results of a successful operation, which resulted in a restoration of high productivity.

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