High-Temperature Wells With Lost-Circulation Demands and Reverse-Circulation Techniques Using Foamed-Cement Systems: Two Case Histories

Summary Drilling activities in diverse areas can pose significant challenges for conventional cement systems and circulation methods. To overcome these challenges, a unique cementing system and a circulation method have been tested in the field with great success. This paper details how these technologies and techniques were successfully used in the cementation process of one casing string in a relatively shallow geothermal well in central California and a relatively deep string in central Wyoming. Globally, many wells experience lost-circulation problems that require the reduction of circulation pressures to allow proper placement of cement to provide annular coverage. To help minimize these circulation pressures, cement was directly pumped into the annulus, significantly reducing placement pressures and allowing placement of the cement with no apparent losses—a process referred to as the reverse-circulation placement technique (RCPT). In the deep and shallow applications discussed, the placement technique and the individual slurry designs address temperature issues.