The extending length calculation of hydraulic drive non-metallic completion screen pipe running into ultra-short radius horizontal well

Focusing on the extending length restriction of the completion screen pipe resistance running into ultra-short radius horizontal well,this paper proposed technology of hydraulic drive completion tubular string running into ultra-short radius horizontal well.Innovative hydraulic drive tools and string structure are designed,which are composed of guide tubing,hydraulic drive tubing and non-metallic completion screen pipe from inside to outside.A novel mechanical-hydraulic coupling model is established.Based on the wellbore structure of an ultra-short radius horizontal well for deep coalbed methane,the numerical calculations of force and hydraulic load on tubular strings were accomplished by the mechanical-hydraulic coupling model.The results show that the extending length of completion tubular string with the hydraulic drive is 17 times that of conventional completion technology under the same conditions.The multi-factor orthogonal design is adopted to analyze the numerical calculations,and the results show that the extending length of the completion tubular string is mainly affected by the completion tubular string structure and the friction coefficient between the non-metallic composite continuous screen pipe and the wellbore.Two series of hydraulic drive completion tubular string structures suitable for ultra-short radius horizontal wells under different conditions are optimized,with the extending limits of 381 m and 655 m,respectively.These researches will provide theoretical guidance for design and control of hydraulic drive non-metallic composite continuous completion screen pipe running into ultra-short radius horizontal wells.

Enhanced oxidation resistance of high-entropy diborides by multicomponent synergistic effects

Oxidation resistance is critical for high-entropy diborides(HEBs)to be used as thermal structural components under oxygen-containing high-temperature environments.Here,we successfully realize the exploitation of(Zr,Ta,Cr,W)B2 HEBs with superior oxidation resistance by comprehensively screening their compositions.To be specific,21 kinds of HEB-xTM(x=0–25 mol%,TM=Zr,Ta,Cr,and W)samples are fabricated via an ultrafast high-temperature sintering technique.The as-fabricated HEB-5Cr samples show the best oxidation resistance at 1673 K among all the samples.Subsquent oxidation investigations further confirm the as-fabricated HEB-5Cr samples possess superior oxidation resistance with the parabolic oxidation behavior across 1473–1773 K.Such superior oxidation resistance is believed to result from the multi-component synergistic effects.Particularly,the Ta^(5+)and W^(4+)cations with high ionic field strengths can promote the formation of 4B–O–4B linkages between[BO4]tetrahedrons by charge balance,which can stabilize the threedimensional skeletal structure of B_(2)O_(3)glass and consequently result in an improved viscosity of the B_(2)O_(3)glassy layer.In addition,the ZrO_(2)and Cr_(2)O_(3)with high melting points can dissolve into the B_(2)O_(3)glass to increase its glass transition temperature,leading to an enhanced viscosity of the B_(2)O_(3)glassy layer.