Drilling techniques for ultra-deep horizontal wells

It is more difficult and hazardous to drill horizontal wells,especially ultra-deep wells of more than 6000 meters,as the drilling gets deeper.In recent years,horizontal drilling techniques have been applied in Tarim Oilfield to comprehensively develop Donghetang region.Six one-step and two-step ultra-deep horizontal wells have been completed in the block one after another,with the drilling depth more than 6300 m on average.The oil and gas output increases considerably in Donghetang oil-gas region after the horizontal wells are put into operation.As a result,the single-well output is three to five times higher than before.Good effect and remarkable economic benefits are obtained.Based on drilling these six horizontal wells,the drilling techniques for ultra-deep horizontal wells are increasingly improved and gets more mature.According to the characteristics of Donghetang region,this paper takes Well Donghe 1-H3 and Well Donghe 1-H5 as an example to introduce such aspects as difficulty analysis,optimizing drilling program design,trajectory control,segmental technical measures,and horizontal drilling fluid in detail.The success obtained from drilling the horizontal wells in the region is a good reference to drilling ultra-deep horizontal wells.