The optimization of spacer fluid properties is very critical for achieving good mud removal in primary cementing. A new, laminar spacer fluid formulation using surfactant/solvents based on engineered-chemistry approach and incorporating high-temperature mud removal (HTMR) fibers was introduced to improve cementing placement results for a major operator in the Gulf of Thailand. The successful implementation of this technology has been accomplished in the field through the application of the Design-Execution-Evaluation workflow best practices.

The team carried out extensive laboratory testing to validate placement efficiency at conditions representative of high-temperature production tubing jobs. A detailed analysis was carried out to compare performance (with fibers) with the legacy system (without fibers) from the same field. The testing results showed significant improvement in the stability of the new system at high temperature and a much higher cleaning efficiency attained using a proprietary test method. Repeat tests were conducted in different laboratories to ensure reliability and robustness against minor changes in downhole temperature.

In order to achieve complete tubing annulus integrity the design workflow required mandatory mitigations for 4 main phenomena (i.e. microannulus, channeling, gas migration and set cement delamination) which, based on detailed analysis of actual data from treated wells, were the main risk factors that could cause integrity issues. This thesis is consistent with indepth analysis of previous wells and therefore supported the introduction of a more technically robust spacer in the production string cementation fluids train to eliminate the risk of channeling.

Prior to actual field implementation of the system on the first well, a dummy "yard" test was carried out onshore to validate mixability and pumpability under simulated field conditions. For operation integrity, a pre-job quality checklist system plus technical co-ordination was implemented between operator fluids team, service company technical engineers and rig-based personnel - this included use of standardized peer review, risk assessments, materials preparation & logistics workflows, plus the application of ISO-certified quality assurance procedures. Three case histories from numerous successful jobs will be presented in this paper.

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