A common problem that occurs in low producing gas wells is the salt precipitation in the near wellbore region or within the wellbore. These salts are generally formed by the changes in pressure but mainly temperature affect the solubility. Salts formation cause additional pressure drop resulting in production impairment and may even result in abandonment of wells. Salt problems occur over a very limited range of producing conditions and are generally seen in mature, depleted gas fields. This paper presents a proactive approach to prevent salt scaling in low pressure gas wells in United Energy Pakistan Limited concession areas.
Early prediction of salt precipitation is vital to optimally produce the well; this depends on individual wellbore pressure & temperature profiles and production chemistry. The paper discusses the diagnostic approach using produced water chemistry, WGR history and Nodal Analysis to predict the optimum bottom-hole pressure to avoid salt precipitation from produced water.
A number of wells in our concession area had severe salt build-up issue and sharp decline in production was observed. Different methods like wellbore cleanout using coiled tubing, mechanical slickline tools and re-perforations to remove salt plugging were implemented but they proved to be short lived resulting high cost, increased intervention frequency and uneconomical gas production from the wells.
In order to mitigate the salt build-up issues, the wells were produced at the optimum bottomhole pressures simulated through nodal analysis, for the given well conditions & produced fluid chemistry, to avoid salt precipitation in the wellbore. The implementation resulted in decelerated salt precipitation from produced water resulting stabilized production, reduced well interventions frequency and improved production economics.