The Research Of Drilling Technology For Tight Oil Slimhole Horizontal Well In Xinj Iang Oilfield

With the rapid development of oil and gas energy industry around the world, the oil and gas resource of large-scale, huge reserves, high resource abundance, better exploration, easy to exploit hold less and less proportion in the remainder of total oil and gas resources, and the unconventional oil and gas resources which demanding high exploration and development technology, not seriously previously, with no major exploration targets, relatively low development efficiency, such as tight oil, will gradually become the central issue of the global oil and gas exploration and development.Tight oil is an unconventional oil resource which embedded in a low porosity and permeability dense reservoir, the reservoir which reservoir permeability less than1mD is defined as the tight reservoir in England. Reservoir permeability less than0.6mD reservoir is defined as tight reservoir in Germany. Reservoir permeability less than0.1mD reservoir (not including crack) is defined as the tight reservoir in America, the current oil industry of China in general,the effective permeability of the reservoir less than0.1mD reservoir is defined as the tight reservoir.There is some problem which restrict drilling efficiency in the tight oil drilling process, especially due to the tight oil extraction usually require special multistage fracturing process in order to achieve the reservoir reconstruction with longer horizontal section generally. It makes the optimization design of horizontal well wellbore trajectory particularly important, and the long open hole section of horizontal wells put forward higher requirements for wellbore stability and hole cleaning, low rate of penetration (ROP),long well construction cycle, have seriously affected the success rate of drilling and the economic benefits of drilling.For more effective development of tight oil combined with geological features of Jimusaer in Xinjiang. It carried out tight oil slim hole horizontal well drilling technology research in order to improve mining efficiency of the tight oil. accumulating experience and reserving technology for large-scale industrial development, and to make some contribution to improve the technical level of the tight oil development, to achieve the tight oil cost-effective development and sustainable development.This study mainly select three representative horizontal wells to be studied and analyzed from the following aspects:1、The horizontal wellbore trajectory model optimization and trajectory fine-grained control, combined with conventional two-dimensional wellbore trajectory model design method, the three wells in Jimusaer have a double increase type-well structure profile design, the field implementation results show that this design method enabled make the downhole directional kick over tools safety drilling, without complex accident, the use of rotary steerable tool to ensure a good smooth borehole and make safe drilling of horizontal wells and reach the target accurately, Meanwhile, as long horizontal section of the horizontal well, it provides a better development of space for the multistage extraction tight oil. The development of tight oil in the the Jimusaer, in order to achieve the transformation of the reservoir fracturing and the formation of orthogonal horizontal seam, the horizontal wellbore azimuth should be along the minimum horizontal stress direction drilling; the minimum horizontal principal stress direction of Lucaogou in Jimusaer depression is North East40°to65°through Dual Caliper logging and FMI imaging logging, jil72_H horizontal well was the first exploration horizontal wells of the Xinjiang Oilfield which make the implementation of the15stages fracturing treatment successfully, more than60m3daily oil production after fracturing and stable last for more than2months, a leading position in the international level of the same type wells. There is special significance to improve the level of development of tight oil and to achieve cost-effective and continuous development of tight oil. The lithology of Lucaogou is dense and drilling along the minimum horizontal stress direction collapse pressure coefficient is1.32to1.38g/cm3. The site drilling fluid system and optimization is potassium calcium-based polysulfonate formula. The reasonable control of the horizontal section drilling fluid density1.50to1.53g/cm3can be better solution to the borehole enlargement.2、Wellbore stability analysis. It get the safety drilling mud weight window through the analysis of six wells wellbore stability in Jimusaer, where vertical wells in Lucaogou reservoir collapse pressure is1.36-1.38, fracture pressure between2.0-2.1, in the conditions of horizontal wells, the collapse pressure is1.32-1.38, fracture pressure is2.5. Vertical wells in the the Permian Wutonggou reservoir collapse pressure is1.35-1.40, fracture pressure about1.85, in the conditions of a horizontal well, the collapse pressure is1.35, fracture pressure is2.4. It is found that the pressure in Jimusaer have the following rules through statistical analysis on three pressure profile of some offset wells in the Jimusaer:pore pressure is greater than the collapse pressure, strata collapse pressure is lower and the fracture pressure is larger in the Quaternary and Neogene strata, mud weight window is wider, the strata which below the Cretaceous or Tertiary formation, the collapse pressure of the formation increases, similar or even greater than the pore pressure and the fracture pressure changed little, mud density window is narrow compared to the upper strata, collapse pressure of Jurassic formation is larger, wellbore stability is poor, prone to the phenomenon of collapse and expanded diameter.3^Drilling speed accelerated Allied Process, rock mechanics parameters calculated and rock mechanical properties profile established in Jimusaer by the logging data, optimized bit selection of the area and application of advanced integrated technology to achieve the ROP breakthrough in the Permian Lucaogou group. The Lucaogou ROP increased by51.09%compared to the ROP of2011,34.78%more than the2012vertical well in Lucaogou group by promoting the application of PDC bits. There is a set of horizontal well drilling allied technology created targeted the the Jimusaer tight oil by the continuous improvement and optimization of the adoption of new technology which provide a solid technical support for the discovery of ten hundred million tons tight oil in Jimusaer depression. Learn from the PDC application and PDC bit selection in vertical well, the ji172_H well have try to use PDC bits in horizontal section, and the result shows that two PDC bits can finished all of the footage completely in the horizontal section,the drilling speed is2.44m/h, increased by99.27%compared to the cone bit, a significant ROP and stroke ROP improved; the ROP of ji251_H well and ji32_H well increased by19.26%and25.41%respectively compared to ji172_H well after the further optimizing the PDC bit model, ROP improved steadily.