Design and Implementation of a Water-Based Micronized Weighting Agent Fluid System for Deepwater Drill Stem Testing Operation in Environmentally Restricted Location

Abstract

The use of micronized weighting agents, in multiple operations, have become more commonplace over the years, with current applications now going far beyond their targeted original purpose of reducing pressure losses in extended reach wells. This specific case reports the development of a fit for purpose system engineered to tackle multiple challenges such as: limitation in using heavy density brines composed of bromides in an offshore environment; hydrate suppression under Drill Stem Test (DST) conditions; weighting agent sagging control; plugging of downhole tools due to heavy solids loading; proper pressure transmission for downhole tools activation; and formation damage prevention. The operation involved the following steps: 1 - development of a Water-based Micronized Weighting Agent Fluid System (WBMWAFS), laboratory testing, simulation evaluation and testing validation for all target properties; 2 - development of an appropriate DST approach with the usage of a designed set of explosives to minimize formation damage and the interaction of the DST fluid with such cargos; and 3 - the evaluation of the overall system performance in order to validate the integrated approach used to design such solution. The DST results indicated that the WBMWAFS is capable of delivering all the technical requirements for a trouble-free operation, with no significant register of weighting agent sag, hydrates or with any variation in fluid properties, whilst enabling a DST operation that demonstrated a negative skin damage during the clean-up period and no damage associated with the WBMWAFS. The WBMWAFS performance opens the possibility of the application of this type of fluid as a replacement for high-density clear brines in many challenging environments.