Application of Mud Loss Control with Chemical Solidification LCM in Well Ming-1

Well Ming-1 is an exploratory well drilled in Block Puguang by the Puguang subsidiary of Zhongyuan Oilfield Company. Lost circulation has occurred many times during drilling the formations on top of the Leikoupo Formation, where fractures and faults develop. These formations are generally broken, have poor cementation and narrow density windows. Methods of controlling lost circulation, such as bridging and plugging, gels of different composition and properties and cement slurry, all failed. Conventional pressure bearing lost circulation control methods and Neotor pressure bearing lost circulation control method have also been applied, and the lost circulation was not satisfactorily controlled and stopped. A chemical solidification technology was then used to control mud losses, and a cross-linking filming fluid was applied to protect the open hole section above the mud loss spots from being fractured while squeezing. Using this technology, the pressure bearing capacity of the formations was strengthened, providing a safeguard for mud loss control. The chemical solidification lost circulation material (LCM) used was a high valent metal ion nano material, and has the ability of slight swelling. It has density that can be adjusted between 1.05 g/cm³ and 1.90 g/cm³, and is stable at temperatures up to 180℃. In the cross-linking filming fluid, a high strength bridging LCM was used to replace the conventional bridging LCM previously used, and a chemical cross-linking solidification material was added to the filming fluid. With this chemical cross-linking solidification material, flowback of LCM slurry will not occur at pressures even higher than 3 MPa. This filming fluid remained stable at temperatures up to 180℃, and when solidified, can stand differential pressures as high as 20 MPa. The successful operation with this chemical solidification LCM provides an effective way of enhancing the pressure bearing capacity of formation to control lost circulation.