Controlling Mud Losses in Well Shunbei 52X with High Temperature Chemical Gels

The well Shunbei 52X is an exploratory well located in the north margin of the Shuntuoguole low uplift, Tarim Basin. This well penetrated a section of the easy-to-break Silurian igneous rocks with plenty of fractures, poor cementation and low-pressure bearing capacity. Repeated mud losses and well kicks happened during drilling from 5,600 m to 6,200 m. High formation temperature of 150℃ was the major reason prohibiting the use of chemical gel to stop mud losses. To deal with mud losses encountered and extend the use of chemical gel, a new high temperature chemical gel was developed, making use of the thermoplasticity of organic gel, the compound action of gel and the retarding effect of modified methyl silicone oil. Laboratory experimental results showed that the thickening time of the high temperature chemical gel can be maintained to more than 4 h, and the compressive strength of the chemical gel after aging for 10 hours was 3.2 MPa. The high temperature chemical gel was used on the well Shunbei 52X to control mud losses; the pressure bearing capacity of the formations at which mud losses have happened in the past was increased to 4.8 MPa as tested, and the equivalent circulation density of the Silurian system was raised to 1.40 g/cm³, successfully resolving the mud losses and well kick problems encountered in drilling the well Shunbei 52X.