Causes and Prevention of Spiral Borehole in Haita Oilfield

The difficulties in stratigraphic correlation and oil and water layer identification caused by the large ratio of spiral holes in Haita Oilfield have negative impact on the geologic stratigraphic division.In order to solve the problem,the creation mechanism of spiral holes were analyzed first;second,combined with the geological characteristics and drilling operation in Haita Oilfield,the main causes of spiral holes were investigated from geological and engineering factors.Technical measures to reduce the incidence of spiral holes were proposed for Haita Oilfield through the research on drilling tools,bits,drilling parameters and drilling measures and on-site technical problems.These measures include:in terms of drilling assembly,use the straight hosing PDM in drilling,beat hosing PDM in well straightening.Stiffness of drill string will be effectively increased with the use of pendulum BHA;with respect to bit type selection,gauge protecting bit should be used to lower the lateral cutting on the borehole wall;in drilling operation,WOB and ROP should be controlled,borehole wall should be fixed in a timely to manner ensure its smoothness.Field tsets showed these technical measures could reduce the incidence of spiral holes significantly,laying sound foundation for accurate stratigraphic division,oil water layer identification in Haita Oilfield.