A Successful Water Shut Off using a Thixotropic Treatment in a Sub Hydrostatic and Highly Aromatic Well, Results in Increased Gas Production of 30% and Reduced Water Production of 63%, Vietnam

An offshore operator in Vietnam faced high water production in a sub-hydrostatic and highly aromatic gas well. In addition to low productivity, the high water cut also strained the water treatment facility. Previous treatment attempts to shut off the high water-producing zones have been unsuccessful due to challenging well conditions. [EB1]With the treatment facility reaching maximum capacity, and expansion of the water treatment capacity being a time-consuming and costly option, a subsurface well intervention was chosen as the most effective way to reduce water production from the well. The well had complex reservoir characteristics due to highly depleted zones that made treatment placement even more complicated, increasing the risk for the operation. The well produces aromatics, and using packers for isolation reduces the packer element sealing performance. Due to the high deviation angle, a Thixotropic Organically Crosslinked Polymer (TOCP) was designed and pumped for the high water-producing zones. A customized solution using a TOCP with extensive laboratory testing was found to be the most suitable treatment design for this well. The new placement technique provided prevention of losses to the depleted zones. The thixotropic treatment provided higher viscosity when pumping stopped, allowing the polymer to seal off at the target zone. As a result of the treatment, the well responded positively. The operator significantly reduced produced water from 5,000 BPD to 2,000 BPD, accommodating the capacity of the water treatment facility. Meanwhile, gas production also increased from 4.6 M SCFD to 6.1 M SCFD, reducing the possibility of the well getting loaded up during platform shutdown. The careful engineering design and laboratory testing played a significant part in the successful campaign, with collaboration from the operator and service company leading this campaign to be a successful project. This approach and solution can help enhance production performance and reduce the cost associated with water production.