Maintaining Well Productivity through Deployment of a Gas Lift Scale Inhibitor: Laboratory and Field Challenges (2003)

Maintaining Well Productivity through Deployment of a Gas Lift Scale Inhibitor: Laboratory and Field Challenges N. Fleming; N. Fleming Dynea Search for other works by this author on: This Site Google Scholar J.A. Stokkan; J.A. Stokkan Dynea Search for other works by this author on: This Site Google Scholar A.M. Mathisen; A.M. Mathisen Norsk Hydro Search for other works by this author on: This Site Google Scholar K. Ramstad; K. Ramstad Norsk Hydro Search for other works by this author on: This Site Google Scholar T. Tydal T. Tydal Norsk Hydro Search for other works by this author on: This Site Google Scholar Paper presented at the International Symposium on Oilfield Scale, Aberdeen, United Kingdom, January 2003. Paper Number: SPE-80374-MS https://doi.org/10.2118/80374-MS Published: January 29 2003 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Fleming, N., Stokkan, J.A., Mathisen, A.M., Ramstad, K., and T. Tydal. "Maintaining Well Productivity through Deployment of a Gas Lift Scale Inhibitor: Laboratory and Field Challenges." Paper presented at the International Symposium on Oilfield Scale, Aberdeen, United Kingdom, January 2003. doi: https://doi.org/10.2118/80374-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE International Oilfield Scale Conference and Exhibition Search Advanced Search AbstractThis paper will focus on the laboratory and field challenges of maintaining productivity in a North Sea well through scale inhibitor deployment via gas lift. Calcium carbonate scale formation commonly occurs during early production of formation water and in this particular well was detected on the downhole safety valve and upper tubing. Several scale management options were considered, however, that considered most likely to succeed was inhibitor injection via the gas lift system.An extensive laboratory evaluation under the North Sea field downhole conditions was undertaken in order to qualify a suitable scale inhibitor/solvent package. While the identification of a scale inhibitor capable of controlling calcium carbonate was relatively simple, the combination of an aqueous based inhibitor with a suitable solvent package proved challenging. The initial product development stage was focused towards identifying compatible blends of various types of scale inhibitors (phosphonates, polymers and vinyl sulphonate copolymers) with different solvent and solvent mixtures. An essential aspect of the formulation design was to minimise the potential for volatile loss from the product to the dry injection gas.Several candidate scale inhibitor/solvent packages were put through a rigorous laboratory evaluation programme under the harshest possible conditions likely to be experienced in the field. From this initial review products were identified as passing pre-defined criteria and showed good environmental qualities with very low viscosities (5cP or less at ambient temperature) before and after volatile loss and had very low corrosivity (0.01mm/y). In addition, the chemicals displayed complete compatibility at concentrations in excess of 50% with the completion fluid, formation water and completion elastomers, and controlled calcium carbonate scaling at a relatively low concentration.The final part of the paper will provide details of the field deployment experiences and challenges of the gas lift scale inhibitors developed.IntroductionArtifical lift via gas lift injection is a common procedure for the enhancement of productivity in those wells with either low reservoir pressure or high water cut and is commonly used in mature fields to prolong productivity. The gas is injected into the production tubing causing aeration and hence a reduction in the hydrostatic head of the liquid column.Within the particular well that the present study was focused on the main problem was scale forming on the downhole safety valve. Under such circumstances the well had to be shut-in periodically with consequent loss of production and a dissolver job performed to remove the scale from the valve. An evaluation was undertaken jointly between the operator and service company and it was decided that the most viable option for the scale management of this well was inhibitor deployment via gas lift.A number of operators have considered the use of scale inhibitor injection via gas lift and have had varying degrees of success(1). For example, it was demonstrated by TFE that during scale inhibitor injection via gas lift in the high temperature Block 3 fields, offshore Angola that the choice of vapour pressure depressant within the scale inhibitor/solvent package was critical(2). During injection of the scale inhibitor/solvent package excessive evaporation occurred to the dry injection gas. This resulted in the viscosity of the injected product increasing significantly leading to clogging of the gas lift system. It was observed that after re-formulation of the solvent system and use of an alternative scale inhibitor that there was no clogging of the subsurface valves and no loss in productivity due to scale fomation. Keywords: paraffin remediation, artificial lift system, differential pressure, wax inhibition, scale remediation, scale inhibition, gas lift scale inhibitor, candidate product, inhibitor, si 0 Subjects: Artificial Lift Systems, Production Chemistry, Metallurgy and Biology, Improved and Enhanced Recovery, Gas lift, Inhibition and remediation of hydrates, scale, paraffin / wax and asphaltene This content is only available via PDF. 2003. Society of Petroleum Engineers You can access this article if you purchase or spend a download.