State-Of-The-Art Composite Centralizer Design - From Unique Lab Testing and Customized Engineering Software to Successful Case Studies in ERD Wells

Torque and drag reduction, high standoff, wear resistance, good cementation, maximum fluid bypass for improved wellbore hydraulics, and good cementation: today’s centralizer design requires new approaches due to the fact that more challenging and longer wells are being drilled. The objective of this technical paper is to outline the design process and centralizer requirements to push the boundaries in both drilling and well completion operations. The approach to developing high-end centralizers begins with the identification of materials that can meet all requirements and well construction challenges simultaneously. A review and gap analysis of current testing standards has been carried out to build a realistic test setup that enables the generation of new centralizer design options. To implement the results accurately into more complex well engineering software modules, specific input parameters and fit-for-purpose solutions have been identified. The results of the described approach led to the design of unique offset centralizers - composed of multilayer composites-that are bonded onto tubulars. The established process resulted in centralizers with an unprecedented friction reduction of 44% compared to steel. The selected materials achieved a wear reduction 30 times better than steel and 80 times better than other composite materials commonly used for centralizers. The lab results have been implemented in software simulations to allow for precise pre-job simulations in torque and drag, standoff, casing wear and hydraulics. Case studies confirm the accuracy of the lab data and well engineering software simulations. Besides the mechanical achievements, the offset design and shape of the centralizers led to an average dynamic pressure reduction of 30%, while lowering peak pressures by up to 50% compared to conventional slip-on centralizers. At the same time, cement bond log case studies show excellent results even in highly inclined and horizontal wells. Enhanced testing, purpose-built design, suitable engineering software and validation through actual case studies have led to a novel centralizer design approach. Multilayer composites provide low friction, high wear resistance, superior fluid bypass, high standoff, and good cementation. The robustness of the centralizers is underlined by their ability to be deployed in challenging casing runs, bonded onto expendable tubulars, or used for casing drilling. In summary, novel composite centralizers pave the way for new drilling frontiers.