Capillary String Deployment Methodology for Tight HPHT Gas Wells Deliquification

Abstract

Abstract De-liquification method utilization has been investigated as a possible solution in sweet and sour gas wells, which suffer from liquid loading issues. There are limited options available to deploy de-liquification technologies in deep, unconsolidated, high temperatures, and in for specific completion designs. This paper discusses the screening of a range of methods and selection of a robust option to deploy downhole injection treatment facilities for the continuous foam. The technical feasibility of a range of downhole foam injection installation methods, while maintaining minimum barriers, has been assessed. The continuous deployment of downhole foam injection is much more efficient and cost effective compared to batch-treating the well with liquid foam. This application maintains the well integrity and avoids well deliverability reduction. The injection system may also be used to continuously inject multi-blend chemicals downhole to treat various other issues such as scale, corrosion, and condensate banking as well as address downstream problems and reduce the need for surface inhibition. Designing the system with the appropriate chemicals and tubing material is the key to success. The selection of material and chemicals should take into account the CO2, H2S, high temperature, and pH concentration in the candidate wells. The chemical injection string can be installed into a live well using a capillary unit, without the need to shut in or choke back production. This can be a rigless installation and will be similar to a coiled-tubing operation, but on a much smaller scale. The capillary unit is small and compact, and is mounted onto a truck/trailer. The unit can quickly and easily be mobilized and de-mobilized for operation, saving time and cost. Routine maintenance to the injection system is crucial for a long-term, successful application. The qualification of the chemicals should be stringent and needs to allow for friction loss through small inner diameters (IDs) that can withstand the pressures, temperatures, fluids and extreme downhole conditions. Using the continuous downhole injection system will positively impact well integrity, improve completion lifetime, assure production continuity, reduce downtime and treatment operating costs, and avoid coiled-tubing descaling operational costs. Installing a downhole treatment system can also be used for other purposes if needed, such as H2S management, scale inhibition, controlling paraffin/asphaltene and treating downhole pumps.