Research on the effect of gas nitriding treatment on the wear resistance of ball seat used in multistage fracturing

• A new application of surface modification for ball seat was proposed and performed.
• The wear mechanisms of specimens were indentified based on tribological tests.
• The on-site experiment indicated that wear resistance was improved obviously.

With the further development of unconventional oil and gas reservoirs, multistage fracturing technique has played an important role in completion process. Wear problem has severely restricted the development of this technique. However, surface modification of fracturing tools has not been studied widely. In this study, ball seats which act as key component in multistage fracturing were nitrided in ammonia (NH3) and the nitride layer characterizations were investigated. Tribological tests were carried out to study the wear resistance of specimens. The test results show that microhardness and wear resistance are improved significantly by gas nitriding treatment. Based on the comprehensive analyses of the wear morphologies and debris, wear mechanisms are identified. The on-site fracturing experiment results indicate that the ball seat shows better wear resistance after gas nitriding treatment.