Application of Chemical Gel LCM on Well Shunbei-3

Well Shunbei-3 is an exploration well located on the north rim of the Shuntuoguole low uplift in Tarim Basin, Xinjiang. This well penetrated the Permian system igneous rocks which have developed fractures, poor cementation, easy-to-break zones and low pressure bearing capacity. Six times of lost circulation during drilling were dealt with bridging agent lost circulation material (LCM) and cement slurry, and the results were unsatisfactory because of low success rate of the first try in lost circulation control. To resolve the lost circulation problem taking place in the low pressure bearing capacity formation of the Permian system, a chemical gel LCM, HND-1, was developed with several nanophase LCMs. Analyses of the mechanisms of HMD-1 indicated that HND-1 had the ability of controlling lost circulation through "synergism" of multiple LCMs, and it can substantially enhance the pressure bearing capacity of formation. Laboratory evaluation demonstrated that chemical gel LCM slurry formulated with HND-1 had thickening time adjustable between 4 h and 20 h, and the compressive strength of the LCM slurry after 24 h was 12 MPa or higher. The HND-1 LCM slurry had density adjustable between 0.8 g/cm³ and 2.25 g/cm³, and was compatible with other drilling fluid additives. The HND-1 LCM slurry was tried in the controlling of lost circulation occurred in the Permian system penetrated by the well Shunbei-3, and good results were obtained. The thief zones were pressurized at 5 MPa, with pressure drop of only 0.2 MPa in 30 min. The equivalent density of the Permian system reached 1.55 g/cm³, satisfying the density requirement for drilling in the Permian system.