Research On The Southern Edge Of Junggar Deep Technology Safe And Efficient Drilling

The south edge of junggar basin is rich of oil and gas resources, which degree of prospecting in deep formation is low and exploration potential is huge. However, the south edge belongs to piedmont nappe tectonic and geological condition is complex, in-situ stress is strong, dip Angle is large and formation pore pressure is high, most long layer is easy hydratable and easy dispersion unstable strata. At the meantime, the mechanical drilling rate is low and drilling accident and drilling complex are frequent. Therefore, deep well drilling construction is difficult, which in turn severely restricted the deep exploration and development progress of south edge.This paper analyzed the characteristics of tectonic formation and drilling geological characteristics in the south edge of junggar basin. Combined with drilling data in the upper and under combination of the south edge, it analyzed the current drilling situation and the difficulties of drilling in the south edge. According to drilling difficulties and geological characteristics of south edge, the characteristics of well bore structure commonly used in the south edge was analyzed. From the aspect of accurate prediction of formation pressure, optimization well bore structure, safe and efficient drilling hole structure has been designed in south edge. And combined with real drilling data, the rationality of well body structure was evaluated.In the face of the problems of poor sidewall stability, deep buried target strata, high formation pressure coefficient, high bottom hole temperature, high safety requirements for drilling fluid drilling in south edge of junggar basin combining with use condition of drilling mud which has been applied in the other well, this paper analyzed difficulties of drilling fluid technology in south edge. Through the experiment, optimization resistance to high temperature and high density water-base drilling fluid treatment agent and formula has been selected, and the various properties of resistance to high temperature and high density water-base drilling fluid has been comprehensive evaluated, and applied in the field test. In the experiments, the drilling fluid system played a characteristic of strong inhibition, ensured the stability of drilling borehole wall under the condition of high density, reduced the accident and complex in the drilling, ensured the successful drilling for test well to design well depth.Combined with drilling data, the paper analyzed the difficulty of increasing drilling speed in south edge, summarized using condition of drill which has been used, researched the drillability of formation rocks in the south edge, referenced drill optimization method, optimized the typical structural drill scheme in south edge, improved drilling rate of penetration. In addition,this paper analyzed and summarized the characteristics of drilling complex and drilling accident, researched the complex accident mechanism in the south edge, used qualitative and quantitative safety evaluation method to achieve the goal of preventing the drilling complex and drilling accident.Moreover, handling methods of typical drilling complex and drilling accidents accident complex have been made. Ultimately, it achieved the result of reducing the rate of accident and complex, raising production rate, shortening the drilling cycle.