Technologies to increase ROP for plastic mudstones,Ying-Qiong Basin
There are high-temperature and high-pressure(HTHP)gasfields mostly in Yinggehai-Qiongdongnan(Ying-Qiong)Basin,west of the South China Sea.A massive set of mudstones in this area,as caprock underlying high-pressure reservoirs,enjoys strong plasticity.And there is another chip hold effect from high-density fluids,leading to hard drilling of bit cutters and slow rate of penetra-tion(ROP).So,three existing approaches to increase this ROP were summed up for the plastic mudstones.And then,some innovative ROP-increasing technologies also available for this kind of rocks in Ying-Qiong Basin were proposed in terms of optimizing the drill-ing fluids,mud weight,bits,drilling parameters,and supporting tools.Results show that(i)mitigating the chip hold at bottomhole or enhancing the cutting efficiency in the mudstones may upgrade the ROP;(ii)the optimized bits matched with increasing tools as well as the preferable fluids and mud weight may achieve better ROP;(iii)motors or supermotors can help significantly improve the ROP in softer formations whereas serious damage to the bits in highly abrasive rocks such as gravels;and(iv)both hydraulic pulse and tor-sional impact tools work well in this increase.The former is more suitable for high-pressure wells targeting relatively shallow forma-tions in eastern basin,while hydraulic motors are more effective for those in deep formations with extremely high pressure.
South China SeaHTHPPlastic mudstoneDrillingROP-increasing technology
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维普
