Advantages of cluster well are that the technology can save land resources, reduce development costs. Sulige gas field is a typical low porosity, low permeability and low abundance. The advantages can meet the requirement of developing and constructing a "scientific, harmonious and environmental friendly" Sulige gas field. There are some difficulties in cluster wells drilling operation in Sulige gas field as following: strong abrasive formation, difficult in trajectory control, low ROP and high drilling costs.
To address these difficulties and promote the application of cluster well, the following researches were carried out: (1) Optimization the numbers of wells under different cluster well network conditions. Combined average horizontal displacement, anti-collision, trajectory control and integrated the cost, the number of wells were calculated, analyzed and optimized. (2) Optimization casing profile. Casing section was optimized into the current "straight - slow bulid - hold-slow drop"; (3) Optimization the well trajectory control mode. A practical and efficient directional well trajectory control technology were explored, and BHAs were developed; (4) Individual design PDC bits. " Spiral knife-wing, short outside the parabolic shape of the crown, double cutting structure, spiral gage" structure of the PDC bits were designed for Sulige formation.
Through innovative research and field integration applications, cluster well drilling supporting package technology have primarily matured in Sulige gas field. The drilling cycle of cluster well was reduced by 35%, with 17.4d drilling cycle in 2011; the ROP was improved by 106.1%, with 14.9m/h ROP in 2011. By the end of 2011, total 468 cluster well grops have been completed and 750 hectares land were conserved. Through the application of cluster well drilling in Sulige field, the development costs were reduced significantly. Cluster well technology has become one of the major development models in Sulige gas field.