Study and Application of Supramolecule Chemical LCM Technology

A supramolecular chemical lost circulation material (LCM) has been prepared based on the supramolecular chemistry theory recently developed. This LCM can be used to control mud losses at different depths. It forms gels of different strengths and elasticity at different temperatures. Lost circulation control techniques have been developed for different rates of mud losses through laboratory experiments. Various problems have been encountered in mud loss control practices, for example, the LCM is unable to stay in mud loss zones, the LCM is easy to mix with water and is therefore diluted, it is difficult for the LCM to be retained and accumulate at the entrance of mud loss channels, and the mud loss channel is difficult to be blocked off, etc. LCM slurries formulated with the supramolecular chemical LCM form gel particles (particle sizes between 100 μm and 2,000 μm) of certain strengths in controllable time span. These elastic deformable gel particles are able to go into and plug formation fractures of 0.15 mm-1.5 mm in size. Fractured formations plugged with the supramolecular chemical LCM have pressure bearing capacity of at least 7.5 MPa. This LCM has been used on three wells (such as the well Ke-205) in Block Zhundong. Field practice showed that a combination of the supramolecular chemical LCM and conventional LCM can be used to control mud losses of different rates during drilling operations. No mud losses have been encountered again in mud loss zones plugged with the supramolecular chemical LCM slurry, indicating that the mud loss control performed was successful. The use of this supramolecular chemical LCM is helpful in reducing the overall drilling cost.