PDC-牙轮复合钻头在南堡油田大斜度井的应用

Application of a PDC-Roller Hybrid Bit in Highly-Deviated Wells of the Nanpu Oilfield

南堡油田大斜度井采用PDC钻头或牙轮钻头进行定向钻进时,存在摩阻大、托压严重、扭矩波动大和工具面不易摆放等问题,为解决该问题,应用了将PDC钻头和牙轮钻头优点结合在一起的PDC-牙轮复合钻头,并根据该油田地层的特性,对其进行个性化设计,设计了"2PDC固定刀翼+2牙轮"和"4PDC固定刀翼+2牙轮"2种切削结构的PDC-牙轮复合钻头。"2牙轮+2PDC固定刀翼"复合钻头和"4PDC固定刀翼+2牙轮"复合钻头分别在NP2-33井和NP5-28井进行了现场试验,在定向钻进过程中均未出现托压现象,工具面稳定,扭矩波动幅度小,造斜性能与牙轮钻头相当,机械钻速与进尺均大幅提高,且返出岩屑粒度大,岩屑分选性好,有利于判别地层岩性和录井。现场试验表明,应用PDC-牙轮复合钻头能解决南堡油田大斜度井定向钻进时托压严重、扭矩波动大和工具面不易摆放等问题,为提高大斜度井定向井段的钻速提供了一种新技术。

Directional drilling operations involving PDC bits or roller bits for highly deviated wells in the Nanpu Oilfield are characterized by significant friction resistance,high back pressures,dramatic fluctuations in torques and difficulties related to placement of tool faces.To solve these problems,PDC-roller hybrid bits with a combination of outstanding features of PDC bits and roller bits were deployed in the Nanpu Oilfield.With consideration to specific geologic conditions,two kinds of PDC-roller hybrid bits,with"2 rollers+2 fixed PDC cutters"and with"4 fixed PDC cutters+2 rollers",were developed.The performances of these two kinds of hybrid bits in the Well NP2-33 and the Well NP5-28 could be summarized as follows:during directional drilling by using the innovative PDC-roller hybrid bit with 2 kinds of cutting structures,no back pressure was observed.At the same time,tool faces remained steady and fluctuations of torques were minor.With build-up capacities equivalent to those of roller bits,the newly-developed hybrid bits enhanced ROPs and footage significantly.Returned cuttings with higher granularity and better sorting might effectively enhance accuracies in determination of lithologic and logging features.Field application performances showed the innovative PDC-roller hybrid bits could effectively remove problems related to back pressures,significant fluctuations in torques,difficulties in placement of tool face and other problems in drilling of highly deviated wells in the Nanpu Oilfield.The bit could effectively enhance ROPs of highly deviated wells.