Research On Speed Raising Technologyof Shale Gas In Changning And Weiyuan Block

Changning-Weiyuan block is the first state-level shale gas demonstration area of China National Petroleum Corporation.There was 10.11*108m3 of shale gas produced at demonstration area in 2016.Predicted the cumulative gas 300*108m3 at the end of 2034.Though the demonstration area made a great stride at the development of exploration,long drilling cycle、slow mechanical drilling rate and frequent downhole complicated conditions severely restricted the shale gas exploration and development speed.This paper made a systematic analysis of Changning-Weiyuan block the engineering geological characteristics and the drilled wells,based on this,teasing out the focus of the shale gas drilling facing difficulties,proposed the comprehensive technical measures of drilling speed in Changning-Weiyuan block,include:well structure optimization design,trajectory optimization design of well factory,strong abrasive PDC bit selection,gas drilling and rotary steering drilling technology and so on.The main result of study:(1)Changning-Weiyuan drilling difficulties:bad borehole stability;Zhenzhuchong-Jia-lingjiang Maokou group lost circulation easily;the 3D trajectory is difficult to control,large friction,sliding drilling,poor directional effect;the upper vertical Wells formation easily inclined.(2)Changning block after the optimization of well bore structure:Ist Φ 762 mm(Drill)+0720 mm(Casing)Jialingjiang,2nd Φ406.4 mm(Drill)+Φ339.7 mm(Casing)top of Feixianguan,3rdΦ311.2mm(Drill)+0244.5 mm(Casing)top of Hanjiadian,4th Φ215.9mm(Drill)+0139.7 mm(Casing)Longmaxi;Weiyuan block:1st 0660.4 mm(Drill)+0508 mm(Casing)Shaximiao,2nd Φ406.4mm(Drill)+Φ339.7mm(Casing)top of Lianggaoshan,3rd Φ311.2mm(Drill)+Φ244.5 mm(Casing)top of Longmaxi,4th Φ215.9 mm(Drill)+Φ139.7 mm(Casing)Longmaxi.(3)It is not only easy to control the trajectory of horizontal well,but also can effectively prevent and reduce the friction of the horizontal well by optimizing the conventional three-dimensional trajectory into a two dimensional trajectory.(4)The optimization result of PDC bit in Changning block:CK505(Feixianguan～Chang-xing),FX55(Longtan～Liangshan),MM55(Longmaxi);Weiyuan block:T1655B(Shaximiao～Xujiahe),MSi616(leikoupo～Jialingjiang),SF56(Feixianguan～Longtan),MDSi613(maokou～liangshan),HCD506ZX(Longmaxi).(5)Comprehensive technical measures for speeding up:the surface uses PDC+ screw +no solid/gas unbalanced fast drilling technology;the straight well section uses the PDC+ bend screw +MWD technology to carry on the fast drilling;The optimization of 3D trajectory wells factory for two dimensional trajectory(slant straight wells + directional wells/horizontal wells)made the poor grinding Hanjiadian～Shiniulan formation optimization of slant hole drilling,using nitrogen drilling speed up.Inclined section and horizontal section is optimized by using PDC bit and rotary steering/oil screw(hydraulic oscillator)for preventing collapse.Reservoir Longma River easy to leak formation using pressure control drilling technology.Application effect of comprehensive speed up technology,compared with the speed increase,the average speed is reduced by 18 days and the average drilling speed is increased by a factor of 58%.The application of the technology of comprehensive speed increase of shale gas in Changning-Weiyuan block provides a guarantee for the safe and efficient development of the domestic shale gas demonstration area.