Key technology of compound circulation loss control and its application to NP1-P4C1 well in Nanpu Oilield

In view of the circulation loss occurred frequently in Nanpu Oilield in shallow permeability layer, fractured layer and reservoir, by researching in laboratory and practice in ield, the key technology of compound circulation loss control is summed up. The compatible effect of diversiied materials is needed for the preparation of compound plugging slurry, in particular the adding of CMC is favorable for circulation loss control. ‘Balance area” is critical to successful circulation loss control. It will move to the left if the effect of circulation loss control is good, otherwise it will turn left or no “balance area” will be formed at all. The intensity and permeability of the “balance area” is important to the effect of circulation loss control. Using static circulation loss control, the static time will take less than 8 hours, within which the sealed protective screen can be established based on the occlusion and swell of sealing materials. The circulation loss control capability will be improved remarkably after second and third circulation loss control, so the technology of multiple circulation control is proposed to be used in the ield. Successful application of the key technology of compound rculation loss control to NP1-P4C1 well indicate that the compound circulation loss control technology is it for the circulation loss prevention and treatment in the Nanpu Oilield.