Designing a successful cleanup job after a hydraulic fracture treatment is always difficult. This thesis shall help creating such a design. The major question is how it is achievable to get all of the overdisplaced proppants as fast as possible out of the hole without getting stuck with the coiled tubing unit. Solving this problem can only be reached by analyzing the main parameters. The theoretical background is given at first by describing the influence of the pressure situation; wellbore geometry especially the deviation in relation to solids velocity, fluid design and pumping speed. After the theoretical part, it is discussed, how cleaning jobs were made in the past in the production area of Lower Saxony and its results. Different systems were tried in relation to different conditions and also some design mistakes occurred. These were pointed out by analyzing 5 wells. For each well the interpretation is based on the starting conditions, chosen fluid system, job performance, conclusion, costs and possible improvements. At the end at well Völkersen Z3 collected information were used to design a successful job with best fitting parameters approached by extended simulation work, after finishing the job even this well shows possibilities to improve. The thesis finishes with a short guideline for fluid decision depending on the deviation and pressure situation. Moreover some advices are given to increase the solids velocity and to do some wiper trips during cleanup.
|Translated title of the contribution||Bewertung durchgeführter Cleanup Arbeiten mit Coiled Tubing nach Frac Stimulation im Produktionsgebiet Niedersachsen|
|Award date||15 Dec 2006|
|Publication status||Published - 2006|