Abstract

In Neuquén, Argentina; the Vaca Muerta formation is the main target for unconventional resources and casing deformation is a recurrent problem observed among most of the main operators in this basin. In our case the first deformations were observed at the beginning of 2011 and as the development of the unconventional fields advanced, they continued to appear and increased in frequency when the horizontal well manufacturing process began. The knowledge of the subsurface mechanisms that cause these deformations motivated numerous internal and external studies that focused on geology, geomechanics, seismic, and reservoir engineering, and led to the application of mitigation measures and risk analysis matrices. One of the ways to validate casing collapse is through the MIT (Multifinger Image Tool) registry which measures the internal diameter with multiple flanges. Based on the opposite measurement, it calculates the minimum passage in a restriction event, data that is used to make immediate decisions and thus be able to continue with the completion operations.

With the exhaustive analysis of this profile and incorporating the geological domain, geosteering, mechanical contrast analysis and the type of stimulation design executed, the casing deformation mechanism can be identified, and, in this study, we will be showing different examples of deformed wells, understanding the mechanism and the proposed mitigation with positive results in the operation.

The objective of this work, beside proposing good practices for obtaining the record (recording mode, configuration of tools and resolution) to follow the workflow of restriction analysis, also intends to show the preliminary conclusions reached regarding the mechanisms involved in generating deformations studied in YPF blocks where the MIT tool, well imaging and additional well information were readily available. The pre-classification of the deformations into two categories used to facilitate the study and the understanding of the mechanisms involved in their formation as it is understood today. The use of the MIT tool is very valuable, but it is necessary to have another complementary tool with low availability such as the tractor to run it on the horizontal section.

In addition, this protocol gives us information about the condition of the pipe at the time the tool is used, not during the stages along the well-bore. Reason why we have added to the analysis the CCL (Casing Collar Locator) measurements took during each of the fracturing stages of the Plug & Perf operations and obtained a good correlation with what was measured in the MIT with no additional costs.

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