Abstract
Abstract
Plug failures, sub-optimal stage design and variable proppant distribution across multi-cluster stages are common issues experienced during plug and perforate hydraulic fracturing. When one or more of these problems occur production potential can be significantly reduced. This case study shows how an operator in the US succesfully applied state-of-the-art fracture diagnostic methods to identify, understand and address these problems and demonstrated improved performances for all three issues in the subsequent wells.
Selecting the right stage design is a crucial factor in the success of a fracturing operation. With three different designs being considered for use during a new development the operator used perforation erosion measurements on the initial well to evaluate how uniformly proppant was placed within each stage.
Data was acquired using a new diagnostic service combining array Ultrasound and array Video sensors. Previously considered as competing services, with users required to select one or the other, combining both technologies and simultaneously acquiring the data provided some clear benefits and improved understanding which are discussed in detail.
The combined technologies provided more comprehensive diagnostics than either sensor could deliver alone. Potential issues with missing data – due either to proppant-filled (plugged) perforations or poor optical clarity - were mitigated resulting in never before achieved levels of data completeness for both surveyed wells. This significantly improved statistical accuracy and provided unequivocal results. In the first well one of the three stage design options was clearly identified as providing better proppant distribution, with 27% higher uniformity than the second-best design. However significant low side perforation erosion was measured for all three designs and casing breaches were observed at some plug setting depths. This indicated the potential for further improvement on future wells, and a change in perforating charge type was recommended along with a review of the plug design and setting procedures. With these changes applied on the subsequent well, the expected improvements were duly delivered. This evolution of stage design was confirmed as providing the best result overall, and with a substantial improvement in uniformity than had been previously achieved in well 1. In conjunction, the revised plug setting procedures eliminated the issues at plug setting depths that had previously been witnessed.
The paper aims to provide anyone targeting improved well performance by using fracture diagnostics with up-to-date knowledge of perforation imaging methods. This will allow informed decisions to be made on how to best deploy the technologies. The case study demonstrates how these methods can be readily applied to identify and resolve common fracture treatment issues, with defining optimal stage design of particularly high value. Learnings can then be used field wide to improve proppant uniformity and ultimately production.