From Laboratory High-Pressure, High-Temperature Technology to Field Success: A Case Study on New Anti-Balling Coating Development

摘要

Bit balling and balling on other bottom hole assembly (BHA) components is a common concern when drilling shale with water-based mud (WBM) because it limits drilling efficiency or in extreme cases can stop drilling, causing costly non-productive time (NPT). Among many strategies which have been created to mitigate the above balling problem, an effective approach is coating the tool surfaces with hydrophobic materials that are generally characterized by high water contact angle. This approach has been pursued by bit manufacturers with some success; however, poor coating durability is still a common concern. Additionally, previous applications are often guided by surface hydrophobicity evaluated at ambient conditions. Elevated temperatures and wellbore pressures can potentially cause the behavior to change and limit effectiveness. Therefore, evaluating the surface hydrophobicity under conditions that closely simulate downhole conditions becomes essential.