混合钻头在涪陵页岩气田的应用

Application of hybrid drill bits in Fuling Shale Gas Field

摘要:

涪陵页岩气田是中国第一个正式投入商业开采的海相页岩气田，历经2013年的开发评价试验阶段及2014-2015年的一期产能建设阶段，通过攻关研究与现场试验应用，创新形成了适合涪陵页岩气田勘探开发的钻完井技术系列，二期产建推进以来，由于埋深的增加、地层的不确定性，对钻井提速提效造成了巨大的阻碍，其中部分复杂层系的钻头选型显得尤为困难，主要体现在常规钻头行程钻速低、起下钻趟次多、定向困难等几个方面。通过对岩石可钻性及定向难点分析，针对平桥区块小河坝组地层研磨性强、砂泥岩交错的特点，优选了121/4 in高研磨性混合钻头；针对二开深层大三维井定向托压严重的问题，优选了121/4 in高效定向混合钻头；针对三开龙马溪组（含浊积砂岩）定向段高造斜率及研磨性强的特点，优选了81/2 in硬地层定向混合钻头。截止2019年2月，3种型号混合钻头在涪陵工区累计使用200余井次，平均减少起下钻4～5趟次，缩短钻井周期6～7 d。混合钻头的优选应用，为二期产建的钻井提速提效提供了技术保障，为下步页岩气田的高效开发提供了钻头选型方案。

Abstract:

Fuling Shale Gas Field was the first marine shale gas field put into commercial exploitation. It went through the development evaluation test phase in 2013 years, and the Phase I productivity construction from 2013 to 2015 with development of a series of drilling and completion technology ideal for Fuling Shale Gas Field exploration and exploitation through field test and application. In the second phase, greater buried depth, and formation uncertainty led to great obstacles in increasing the drilling speed; particularly the bit type selection was difficult for some complex formation. It was mainly reflected in the low drilling rate per round trip with conventional bits, multiple times of tripping, and difficult orientation. With the analysis of drillability and directional difficulties, 121/4in high abrasive hybrid drill bits were selected for strong abrasive and alternating sand and mudstone in the Xiaoheba Formation of Pingqiao Block. In order to solve the serious problem of directional drag force in drilling of the second section in long reach three-dimensional wells, 121/4in high-efficiency directional hybrid bits were optimized. In view of the characteristics of high formation deflection rate and strong abrasiveness in the build section of Longmaxi Formation (containing turbidite sandstone), the 81/2in hard formation directional hybrid bit was optimized. Up to now, the three types of hybrid drill bits have been used in the Fuling work area for more than 200 times totally, with an average reduction of 4 to 5 trips and cutting short of the drilling duration by 6～7 days. The selection of the hybrid bit has provided technical guarantee for the drilling acceleration and efficiency improvement in the second construction phase, and also provides the bit selection scheme for the efficient development of the following shale gas fields.