悬空侧钻技术在常规水平井中的应用

APPLICATION OF OPEN HOLE SIDETRACKING TECHNOLOGY IN THE CONVENTIONAL HORIZONTAL WELLS

胜利油田的绝大多数常规水平井可采用悬空侧钻工艺,悬空侧钻一般不需起钻,直接将钻具提至侧钻点进行施工,这种方式能节约钻井周期,降低钻井成本,但如何保证悬空侧钻的成功率却需要考虑许多因素。侧钻点选择是侧钻成功的先决条件,需要考虑地层特性、狗腿度、目标靶点等因素影响,侧钻点优先选在造斜段,有利于后期管柱的重入;钻头侧向力大小也是影响侧钻成功率重要因素,运用纵横弯曲梁理论分析结构弯角、井径、井斜角、钻头到弯点距离对钻头侧向力的影响,软地层常规钻具组合能满足侧钻要求,而硬地层通常需要增大钻头侧向力。

The open hole sidetracking technology was used in the majority of conventional horizontal wells in Shengli oilfield. For this technology,the drilling string would be directly raised to the sidetracking point instead of tripping out,which could save the drilling cycle and reduce the drilling cost. However,many factors should be considered to ensure the success ratio of this technology. The determination of side tracking point was a prerequisite for the sidetracking success. It needs to consider the effect of formation characteristics,dogleg,target and etc. on the sidetracking,the sidetracking point should be selected in the building up section,which was conducive to the strings re-entry. Bit lateral force was also an important factor influencing sidetracking success. By using the theory of vertical and horizontal bending beams,the influence of the structure angle,hole diameter,deviation angle and the distance of the bit to the bending point on the bit lateral force was analyzed. In soft formation,the conventional BHA could meet the requirements of sidetracking, however, in hard formation, bit lateral force should be enhanced.