Jake Delap, OXY Oil & Gas
OBJECTIVES/SCOPE:
Cleaning out a lateral is a powerful tool for restoring production in mature wells, but sometimes the hydraulics will not allow circulation with fresh water. An interesting technique for cleaning out such laterals has been field tested in the Delaware Basin, and it has potential application in many basins. As laterals age, a proper cleanout using this new method can restore production after a frac hit, prepare it for a refrac or for spotting acid across the lateral, run casing patches, clean out the top of a fish, and numerous other applications.
METHODS PROCEDURES, PROCESS:
Cleaning out laterals with low bottomhole pressure (BHP) can be difficult when using water or brine because the hydraulics prevent adequate circulation. Often conventional techniques like nitrogen or diversion using rock salt or bio balls are required to clean out such wells, but these techniques are costly and can be unreliable. Microbubble / aphron based fluid systems can often work better than Newtonian or gelled fluid systems because: a) fluid weight can be lowered to 4.5 ppg, reducing the hydrostatic gradient, and b) rheology is improved to increase the carrying capacity of solids, reducing the risk of getting stuck.
RESULTS, OBSERVATIONS, CONCLUSIONS:
Across our industry there are thousands of laterals that need to be cleaned out occasionally to maximize recovery. Due to length, debris volume, and BHP, traditional techniques such as venturis, nitrogen, rock salt, and bio balls are not always the best tool for the job. An 18-month trial was conducted by the Oxy Delaware Basin team. This trial consists of 23 lateral cleanouts using a microbubble/aphron based fluid system across both Texas and New Mexico.
We have had a variety of results in performance response, including well enhancement, restored base production, no observed impact, poor candidate, negative performance, circulation not established, and microbubble / aphron based fluid system not needed for circulation.
We have learned that these jobs are not cookie cutter and need keen engineering for both candidate selection and execution. Based on our field experience, we have developed a process for candidate selection, job planning, and execution that can deliver a fully cleaned out lateral for maximized production. There is still more to learn, but we would like to share findings so that our industry can work together better maximize ROI across multiple basins.