Key technologies for trajectory control in deep CBM horizontal wells,Nalinhe area,Ordos Basin
Most deep coalbed methane(CBM)horizontal wells in Nalinhe area are confronted with difficult trajectory con-trol and low drilling rate in effective reservoirs.Therefore,taken JA-31NH6 well as an example,some key drilling technol-ogies which include the multi-factor to optimize well location,the multi-marker to condition targeting,and the multi-means for precise steering were studied from drilling engineering,well logging,mud logging and 3D seismic exploration.Results show that(i)the micro-amplitude structure is exactly characterized through 3D seismic combined with trend struc-ture,and the well location is optimized on the basis of CBM thickness,maturity,and roof and floor lithology;(ⅱ)the devia-tion is fine-tuned for targeting in accordance with 6 marker beds represented by Maoergou limestone;(ⅲ)both vertical pro-file of lithological combination and parameter tables of each lithology are established by making full use of drilling,well-logging and mud-logging data,especially near-bit azimuth gamma and elemental mud logging.And accurately,the drilled lithology can be analyzed,the bit position can be traced,and the horizontal section can be steered;and(iv)the CBM thick-ness,micro-amplitude structure,and wellbore trajectory and quality as a whole should be taken into consideration during drilling the horizontal section in an effort to improve the development effect by integrating geology with seismic engineering together with fine trajectory adjustment.As a result,the drilling rate is increased from 50.7%to 91.6%,which achieves the scientific,efficient,optimal and fast drilling in deep CBM horizontal wells in this area.These drilling technologies may provide reference for such deep CBM horizontal wells in other areas.
Ordos BasinDeep coalbed methaneHorizontal wellOptimization of well locationTrajectory control
NETL
NSTL
万方数据
