Optimum Drilling Technology Studies On Ultra-deep Wells In The External Block Of Tahe Oilfield

Tarim Basin in Xinjiang is one of key oil and gas exploration area for Sinopec, also the main oil and gas exploration blocks to implement the national western development strategy and cultivate large oil and gas fields. After nearly ten years of overall development, the main block has formed a series of mature and supporting drilling &completion technology. However, with the main oilfield Ordovician carbonate reservoir reserves decreasing gradually, it needs to move on its peripheral blocks for exploration and development. As we all know, drilling in external block of Tahe oilfield will face complex geological conditions, difficulties in casing program design, deviation problem, low ROP and long drilling period etc. Through on the study of optimizing casing design, deviation control & fast drilling technology, bit selection and comprehensive drilling technology, the project forms an effective ultra-deep drilling technology, succeed to complete the tasks, achieve the required specifications, and gained the expected results.In the course of this project, through literature research and geology, drilling and logging data analysis and processing, the formation pressure profile of studied area was established and well profile optimization scheme was proposed. And then in-site following study was done in order to adjust the scheme immediately, good results have been gained finally. Through the well casing program optimization, drilling period of TP101 well reduced 27.3%, the average drilling rate increased 35.3%.According to the present development condition of fast anti- deviation drilling, in order to solve the deviation problem in Shannan area, we figure out measures of fast anti-deviation drilling technology, the technical schemes of fast anti- deviation drilling are given, meanwhile, the on-site applications make better results.The technology of Bits-Selection based on Grey Relational method combined with reasonable drilling parameters makes better technical target in ultra-deep drilling in the external block of Tahe oilfield; PDC bit + positive displacement motor drilling technology and turbine drilling technology are the key fasten technologies in the external block. PDC bit+ positive displacement motor drilling is relatively mature, turbine drilling technology still needs to further improvement. The technologies used in the construction of six ultra-deep wells in the TaHe oilfield have made good effects, which include optimizing casing program and bit type combined with vertical and fasten technology and compound drilling technology. The average depth is 6493m in test wells and the average ROP is 7.79m/h, compared to the Ultra-deep wells drilled in the block in 2008 year, the average ROP increases 19.3%.