Optimized Cluster Drilling Technology Delivers Outstanding Results in Sulige Gas Field,Ordos Basin

摘要

Many development strategies have been evaluated and applied in pilot tests by CNPC in the Sulige Gas Field that is typically subjected to low permeability, low pressure and low quality. Cluster well technique was deemed to be the most appropriate way to deal with the "three -low" reservoir related problems,especially in the vulnerable eco logic environment of desert area. The early pilot test, however, severely restricted its application on larger scales due to the longer drilling cycle and higher drilling cost compared to vertical wells. The Sulige development team was driven to re -design and optimize the cluster drilling project,with the principal objectives to further improve the rate of penetration (ROP) and reduce the unit gas development cost. This paper will focus on the optimized cluster drill ing concept that has been successfully applied in recent years within the Sulige Gas Field, which is the largest gas field in China to date. A "Cluster" usually consists of a straight well and several directional wells drilled from a single pad loca tion. Based on the optimization of wellbore profile,well trajectory,PDC bits,bottom hole assembly and drilling flu id, a complete set of cluster well techniques in a safer and faster drilling mode have been formed. Its application has resulted in an average ROP improvement of more than 36% and a dramatic increase of short -and long — term well economics,compared to previous cluster wells. The mature "Cluster" pattern triggers its extensive application in Sulige and promotes its trial applications in the Hailaer -Tamtsag Basin and Sichuan Basin. This paper will present the optimized measures of cluster drilling and operational results within the Sulige gas field, and will discuss the cluster drilling challenges, relevant drilling operations and subsequent post well evalua tion. Its objective is to conclude optimized drilling performance in the Sulige Gas Field and to provide guidelines for successful development of other oil and gas fields with similar reservoir characteristics.