Friction and Casing Wear Factor Characterization

Abstract

Abstract Casing wear is a concern among O&G operators worldwide since it can lead to well integrity issues. Wear can appear on both elements, drill pipe and the external casing, resulting in the reduction of the tubular wall thickness affecting its performance. To address the topic, a tribometer was developed based on the standard API STD 7CW (2015), including a rotating element that slides against a fixed element while being exposed to drilling mud, leading to the obtention of coefficients of friction (CoF) and casing wear factors, for different combinations of Oil Country Tubular Goods (OCTG). To estimate CoF and casing wear factors, more than 70 laboratory tests were performed combining steel grades under repetitive and consistent conditions. Contact force was fixed and maintained between both elements during test. CoF were calculated by direct torque measurement, while casing wear factors were indirectly defined by measuring the material loss volume. Results obtained in CoF were in a range of 0.3 and 0.5, being higher than the values in open literature. They also showed a relation between drill element grades and higher values of CoF. Three zones were detected when evaluating CoF results together. Analyzing casing wear factors, the results obtained were in a range from 0.03 to 0.3 (1/psi E-09), this range is slightly lower than public data available. Different testing conditions such as torque and displacement were evaluated to assess the behavior of 28Cr alloy.