Abstract

This paper details the process of designing and executing a frac pack operation in a previously gravel-packed formation. Challenges and solutions are discussed as well as the methods used to properly squeeze fluid and proppant into the formation.

During the last 13 years in China, a single-trip multizone (STMZ) gravel-packing system has been widely used in Bohai Bay for sand control. Most of the wells were initially completed using high-rate water packing methods and then were sidetracked once production reduced to a certain level. However, operators desired a lower-cost work over plan. The proposed method involved recompleting a previous well by running service tools into the well to perform fracture packing within the existing multizone gravel-pack completion. High-viscosity fluid was pumped into the formation as a prepad, and then formation fracture packing was performed.

The successful treatment execution presented in this paper demonstrates the process of cleaning the wellbore for recompletion. Using the STMZ system proved the downhole service tool could be safely tripped back in and out of hole in the same trip following fracture packing of a previously gravel-packed multizone well completion. The method also shows that, through careful preplanning and designing of the tool and treatment, the risk of failure caused by a stuck tool string, unwanted fluid loss, or premature screenout can be minimized. The job execution and lessons learned along the way can also provide a guideline for improvement of future treatments in similar situations.

This paper presents the first successful fracture packing application in a previously gravel-packed well. The method presented provides a new method to enhance production of mature wells without performing a sidetrack, significantly reducing costs by recompleting the well.

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