Novel Combination Iron Sulfide-Corrosion Inhibitor Development, Testing and Field Assessment for an Integrated Scale Management System

Abstract

Abstract This paper concerns wet gas production in East Texas area highlighting the use of an innovative approach to solve a unique severe scaling challenge with a cooperative operator. The scope of application spans some 1,200 wells in the Central and East Texas area where the challenge was gas production with associated corrosive fluids in low pressure condition, leading to significant deposition of carbonate and iron sulfide scale within the production tubing. This paper details unique challenges and solutions in developing a single lift chemistry that prevents inorganic scales, particularly iron sulfide scale in the production tubing whilst providing adequate lift to the well. Development work presented includes laboratory and field foamer testing, anoxic iron sulfide scale testing, and autoclave corrosion testing. This was made more challenging due to the high downhole temperatures of 300°F with a pressure of 1,000 psi and a mixed sweet / sour gas with a composition of 2.2mol% CO2 and 0.75mol% H2S. Testing showed that application of these products at 2,000 to 4,000 ppm were able to stabilize gas production, reduce the corrosion to acceptable corrosion rates and prevent the deposition of iron sulfide scale in static and dynamic tests. Extensive detail is provided during the field trials and the monitoring regimen that was put in place to monitor all functionalities provided by this chemistry. As this was across a whole host of different well types significant data was generated and a wealth of information and lessons learned for the industry can be extracted from it. The paper concludes with the overall lessons learned and summary of the validity of this technology and how it could potentially be a game changer for the industry at large in East Texas where gas well deliquification combined with corrosion and scale formation is a shared challenge.