The Study On Drilling Technique In Complex Structural Well In TUHA Oilfield

Tuha oilfield belongs to the typical "low pressure, low porosity, low permeability",three low oil fields,single vertical well production is low and overall development effect is not obvious. Using the fishbone branch well and horizontal well with long horizontal section to drill can effectively increase drainage area of the oil and gas reservoir development, enhance oil recovery, achieve the goal of efficient development with low cost.Fishbone branch well can dangle to dsidetrack and have difficulty running drilling tools as well as the defects of long well section, long penetration footage, large exposure area of reservoir and underground complex when drilling within the target stratum. The fishbone wells technology in Tuha oilfield is still in its infancy, related technologies need further improvement.In this paper, mainly study fishbone branch well’s track design, trajectory control, antifriction, resistance dimishing and well completion methods, put forward a set of fishbone branch well drilling technology suitable for Tuha oilfield. The technology is aplied to four-branch fishbone horizontal well, Yuping 8 Well, and verified correct. There is no downhole complicated condition in the process of drilling. now the production stabilizes 18 t/d, more than three times the production of its adjacent vertical wells.The drilling fluid volume and cuttings volume of slim-hole drilling can be reduced by 75% than that of conventional well bore, saving25-50% drilling cost, so this technique is very suitable for three low oilfield like Tuha. to meet the need of lowering the cost and increasing efficiency. Long horizontal section of slim-hole well in drilling is faced with puzzled problems, such as: the stability of shale in horizontal section, well bore cleaning, drill bit ‘s backing pressure and so on. The problems can lead to low drilling speed, long drilling cycle and seriously restrict the development of technology..In this paper, according to the study of the friction torque in long horizontal section of slim-hole well, drill string assembly and optimization of drilling parameters, trajectory control technology and well bore cleaning technology, we form a set of drilling technologies suitable for long horizontal section of slim-hole well in Tuha oilfield.This technology solves the problems of drilling speed and drilling cycle and makes sure to enhance the production of Tuha oilfield effectively.