Investigation and Feasibility of Underbalanced Drilling at Fractured Formations; Case Study: Field-A in South of Iran

Recently under balanced drilling (UBD0 has been used with increasing frequency . The main purpose of using UBD is to minimize problems associated with invasive formation damage , increase rate of penetration and reduce well stimulation and economic study. however , UBD is not a soluthionfor alll formations in some cases there are distinct disadvantages.therefore it is important to evaluate formations before deciding to drill a well under balanced feasibility of UBD and economic advantages are two main parameters. the first one consists of analyzing petro physical data to determine whether a particular well is to potential UBD candidate and selecting type of UBD fluid and second one consists of ananlyzing cost of drilling. the main objective of this study is to evaluate the feasibility of drilling in A-field is southern iran using UBD. the available petrophysical ,reservoir and well data has been compared with the criteria of using UBD and suggestion have been made upon that. this study emphasizes on fraction stability minimum formation damage and economic advantages.

Keywords:

under balanced drilling , lost circulation of mud drilling , formation damage.