Timano-Pechora is one of the fast growing hydrocarbon-containing areas of Russian Federation, possessing reserves of already discovered and being developed fields, as well as high offshore potential. Operators’ goals on intensive area development and increased well production rates were followed by a splash of lateral and sidetrack drilling in recent years. Doubtless, the upcoming huge regional projects would require a multiple increase of horizontal drilling work scope at an early date.
On this background, it’s necessary to distinguish a range of oilfields with highly interbedded terrigenous and carbonate rocks in their structure. Just 5 years ago drilling companies ran only insert cone bits of high IADC code with enhanced gauge protection due to hardness and abrasivity of rocks. Such a conservative method led to low ROP and high NPT for additional round-trips. Modern generations of PDC drill bits allow successful passing of homogeneous carbonate interval with a displacement motor (PDM) in few runs. However, deeper lying frequent interbeds of shale, siltstone, limestone and dolomite cause unpredictable torque on PDC bit, severe bottomhole vibrations and loss of BHA steerability. Therefore, drilling and service companies are forced to run roller cone bits to ensure planned build-up rates and hole quality. The conducted analysis of field data outputs that no type of drill bit (i.e. roller cone or PDC) can be effective enough under described conditions.
This paper depicts alternative combinations of BHAs and drill bits to provide higher technical and economical drilling indicators. It mainly focuses on the pair of conventional PDM with hybrid drill bit utilizing combined PDC and roller cone bits elements. Recommendations on drill bit selection are given based on case studies in similar conditions from two wells of Canadian Arctic oilfield.