Intermediate casings in the build sections are subject to severe wear in extended-reach drilling. This paper presents a new method for predicting the depth of a wear groove on the intermediate casing. According to ene...Intermediate casings in the build sections are subject to severe wear in extended-reach drilling. This paper presents a new method for predicting the depth of a wear groove on the intermediate casing. According to energy principle and dynamic accumulation of casing wear by tool joints, a model is established to calculate the wear area on the inner wall of the casing. The relationship functions between the wear groove depth and area are obtained based on the geometry relationship between the drillstring and the wear section and the assumption that the casing wear groove is crescent-shaped. The change of casing wear groove depth versus drilling footage under different-sized drillstrings is also discussed. A mechanical model is proposed for predicting casing wear location, which is based on the well trajectory and drillstring movement. The casing wear groove depth of a planned well is predicted with inversion of the casing wear factor from the drilled well and necessarily revised to improve the prediction accuracy for differences between the drilled well and the planned well. The method for predicting casing wear in extended-reach drilling is verified through actual case study. The effect of drillstring size on casing wear should be taken into account in casing wear prediction.展开更多
Platforms I and II are steel structures located in offshore areas southeast of the Zhujiang (Pearl) River Delta, the northern South China Sea,. in about 110 in water depth. The jackets, with aluminum sacrificial anode...Platforms I and II are steel structures located in offshore areas southeast of the Zhujiang (Pearl) River Delta, the northern South China Sea,. in about 110 in water depth. The jackets, with aluminum sacrificial anodes for cathodic protection (CP) of the immersed zone, were launched in March 1995. In May 096 a CP survey showed that, after almost one year of service, a low polarization level had been achieved and some extended unprotected zones existed; mainly in the deepest part of the Platform II. Further to this, a joint activity was decided in order to assess the need of a possible retrofitting of the CP systems. The results of the activity carried out are dealt with, including technical and economical comparisons amongst several retrofitting options, both with sacrificial anodes and with impressed current systems. The adopted solution is illustrated and data are reported on the level of protection presently achieved.展开更多
基金support from the national projects (Grant No.: 2009ZX05009-005 and 2010CB226703)
文摘Intermediate casings in the build sections are subject to severe wear in extended-reach drilling. This paper presents a new method for predicting the depth of a wear groove on the intermediate casing. According to energy principle and dynamic accumulation of casing wear by tool joints, a model is established to calculate the wear area on the inner wall of the casing. The relationship functions between the wear groove depth and area are obtained based on the geometry relationship between the drillstring and the wear section and the assumption that the casing wear groove is crescent-shaped. The change of casing wear groove depth versus drilling footage under different-sized drillstrings is also discussed. A mechanical model is proposed for predicting casing wear location, which is based on the well trajectory and drillstring movement. The casing wear groove depth of a planned well is predicted with inversion of the casing wear factor from the drilled well and necessarily revised to improve the prediction accuracy for differences between the drilled well and the planned well. The method for predicting casing wear in extended-reach drilling is verified through actual case study. The effect of drillstring size on casing wear should be taken into account in casing wear prediction.
文摘Platforms I and II are steel structures located in offshore areas southeast of the Zhujiang (Pearl) River Delta, the northern South China Sea,. in about 110 in water depth. The jackets, with aluminum sacrificial anodes for cathodic protection (CP) of the immersed zone, were launched in March 1995. In May 096 a CP survey showed that, after almost one year of service, a low polarization level had been achieved and some extended unprotected zones existed; mainly in the deepest part of the Platform II. Further to this, a joint activity was decided in order to assess the need of a possible retrofitting of the CP systems. The results of the activity carried out are dealt with, including technical and economical comparisons amongst several retrofitting options, both with sacrificial anodes and with impressed current systems. The adopted solution is illustrated and data are reported on the level of protection presently achieved.
