First Time Worldwide Application of Glass Reinforced Epoxy Lined Tubing for Prevention of Asphaltene Deposition on Tubing in Oil Wells – A Case Study from Kuwait
Authors: Edappillikulangara Chinnappan Reji , Telang Milan , Quttainah Riyad , Radhakrishnan Gokulnath , Fernandes Alwyn , Rajendran Kailas 
Published: March 2021

Asphaltene deposition in production tubing is a major flow assurance challenge. Common strategies to mitigate Asphaltene deposition downhole include mechanical or solvent cleanouts and chemical inhibition. These are associated with production deferment, high job costs, HSE risks and operational issues. In a worldwide first, Kuwait Oil Company (KOC) has addressed this challenge using Fiberglass (GRE) Lined Production Tubing. This technology was implemented in two trial wells. This paper chronicles the different mitigation strategies employed by KOC and presents the findings of the above-mentioned successful trials.

Tendency of scale to stick on smoother, non-metallic surfaces, is known to be less than on bare steel surface. KOC had trialed internal coating to mitigate Asphaltene deposition in tubing, but the experience was not satisfactory. KOC has been successfully using GRE lined tubing for corrosion protection and scale prevention in oil and water wells. Considering GRE's smoother surface, lower zeta energy and thermal insulation, it was decided to conduct a trial of GRE lined tubing in wells with Asphaltene deposition problems. Frequency of cleanout and Well Head Pressure (WHP) trends, before and after installation of GRE Lined Tubing, were compared for evaluation. The paper chronicles the trial results and provides a comparison of implementation costs against currently employed tubing cleanouts by Coiled Tubing (CT) using a Diesel-Toluene mixture.

Two wells, requiring frequent tubing cleanout of Asphaltene, were selected as candidates. Trends over a period of 13-15 months after installation of GRE lined tubing showed up to 74 % reduction in WHP decline rate compared to pre-installation periods. Cleanouts were avoided against an earlier frequency of 3 to 3.5 jobs per year. This resulted in following benefits: (1) Direct annual operational savings of 519,750 US $ per well (2) Additional production by increased uptime of 1 to 1 ½ months (3) Avoidance of Coiled Tubing sticking, occurring in similar wells, and the resultant workover cost (4) Eliminating production deferment due to this workover (5) An environment friendly and safe methodology not requiring handling of toxic, highly flammable Toluene, used for the clean outs. Comparison of the economics show clear-cut benefits of GRE lined tubing over tubing cleanouts. In view of the applicability in most of their high API gravity Jurassic oil wells, KOC has decided on wide scale implementation of this technology.

As this is the first known case of its kind worldwide, we expect that this paper will be highly beneficial to operators faced with challenges in producing Asphalteinic oil and those engaged in CO2 EOR campaigns. Besides sharing experience, the authors aim to generate global operator engagement to optimize this new solution, possibly combined with other solutions, to tackle Asphaltene deposition as efficiently as possible.