异向双弯钻具组合设计与防斜应用

Design of the double-titled U-joint housing drilling tool and its application to well deviation control

井斜一直是常规钻井中的一大难题,之前以钻柱静力学分析为基础提出的防斜钻具组合虽取得了"防斜钻直"的效果,但需要降低钻压来保证防斜效果。为此,通过对异向双弯钻具防斜机理和侧向力模拟分析,评价了其防斜打快性能:随着弯接头偏心角、钻压和扶正器的高度的增大,防斜效果越明显;随着端部和中部直壳体的长度增加,造斜率有所下降,且稳定性会更好。进而提出并设计了新型异向双弯防斜钻具组合,优化改进了异向双弯钻具的弯接头、短节和单边扶正器等关键部件的技术参数,从而保证了该钻具组合具有较好的防斜效果并能够施加足够的钻压来提高机械钻速。经过2口井的现场试验证明,平均钻速提高了73.93%,井斜角控制在10°以内,实现了复杂井段的防斜打快,取得了良好的经济效益。

Well deviation is always a bottlenecking problem during the conventional drilling process.Although this problem can be solved by the previously used deviation-control BHA based on the static analysis of the drilling string,the WOB has to be reduced.In view of this,the study on the mechanism of double-titled U-joint housing(DTU) drilling tool is made,and a simulation analysis is conducted regarding the side force on the tool to evaluate its deviation-control performance.It is observed that the deviation control will become better with the higher eccentricity of the bent house,the higher WOB,and the higher stabilizer placement.And the longer the end and middle sections of the housing,the lower the buildup rate will be and the higher the stability will become.Thus,a new type of DTU is then developed with its technical parameters optimized including the critical parts like the bent housing,the sub and the stabilizer,thereby to help achieve not only a better deviation control performance but a higher ROP under enough WOB.Through pilot tests in two wells,the average ROP was enhanced by 73.93% and the well deviation is controlled within 10°.Therefore,this new type of DTU is proved to help achieve economic benefit.