川东北河坝区块大斜度井轨道优化设计技术

Well trajectory optimization for highly deviated wells in the Heba Block,northeastern Sichuan Basin

中国石油化工股份有限公司川东北河坝区块大斜度定向井,在不同工况作业(如正常、滑动钻进、起下钻等)过程中都存在着造斜段轨迹控制难度大、施工摩擦阻力大等难题。为此,从井眼轨道设计入手,在系统分析常用轨道设计方法的基础上,得出除了查图法和作图法外,一般应采用解析法进行设计的认识,设计思路:首先根据给定设计条件求出不同轨迹关键参数,然后求出轨道节点数据,最后求出轨道分点数据。结合该区块大斜度定向井的特点,对轨道设计中的关键参数、轨道剖面类型等进行优化,优化设计原则:①轨迹设计必须满足地质靶点、中靶方位以及现场施工条件(如钻机型号、定向仪器等)的要求;②井眼轨迹几何形状最优化设计首先须满足常规导向钻具组合造斜率的要求、特定套管柱和井眼轨迹的相互适应性,其次要求轨迹最短、管柱的摩擦阻力相对最小,最后要求轨迹光滑过渡和井眼曲率均匀。优化设计的步骤:先根据地质参数(如靶点垂深、水平位移等)和工艺水平(如定向工具型号、性能等),对造斜点以下井段进行钻井方式和钻具组合设计,然后才能对大斜度井井眼轨道进行优化设计。将所形成的大斜度定向井轨道优化设计技术成果应用于HB1-1D等多口大斜度井钻井设计和施工作业中,均顺利实现了地质中靶和完井作业,为该区块后续部署井的轨道设计提供了依据。

Such difficulties as trajectory control at the build-up section and high friction forces in operation are easily encountered during normal drilling,sliding drilling or tripping operation in highly deviated wells at the Heba Block,operated by the Sinopec in the northeastern Sichuan Basin.Therefore,a systematic analysis is made of the commonly used trajectory design methods and it is found that the analytical method is preferred for well trajectory design besides the table/figure looking-up and mapping/plotting methods.The basic procedure of this recommended method is as follows:First to calculate the key parameters of different trajectories according to the given conditions,then to calculate the nodal data of the trajectories,and finally to calculate the data of diverting points.In combination with the specific features of highly deviated wells in this block,trajectory parameters and profile patterns are optimized by the following principles.(1)A well trajectory design should meet the requirements of geological target,target azimuth and operating conditions,such as drilling rig types and directional drilling instruments used.(2)The wellbore geometry should first satisfy the need of the build-up rate of the conventional steering BHA;being co-adaptive should be necessary between the trajectory and the specific casing string;the shortest length of the trajectory should be the most preferable;the tubing friction resistance should be as small as possible;and smooth transition and uniform borehole curvature should be required for the well trajectory design.Before optimizing the high-angle section,the operators should first optimize the drilling mode and BHA for sections below the kickoff point based on the geological parameters,such as the defined True Vertical Depth(TVD)of the target,horizontal displacement,etc.,and the state-of-the-art drilling technologies,such as directional drilling tool types and behaviors,etc.With this set of optimization technology applied to the planning and drilling of such wells as HB1-1Detc.,successful targeting and completion operations have been completed,which provides reference for future well trajectory designs in this block.