降低射孔爆轰伤害的超深探井测试管柱安全控制措施

Safety control measures for ultra-deep exploration well test string to reduce perforation explosion damage

国内超深探井试油采用射孔-测试联作工艺,超深井小井眼射孔易出现封隔器下部管柱及封隔器中心管弯曲和断裂等井下复杂情况。根据气体克拉柏龙方程和爆轰气体能量公式,导出射孔爆轰井底和封隔器处最大峰值压力计算公式;根据管柱力学屈曲理论和材料力学弯曲理论,导出射孔段管柱的弯曲应力计算公式;结合峰值压力下的活塞效应,导出射孔冲击载荷作用下管柱的应力计算公式,判断管柱的强度安全。根据射孔段管柱力学分析成果,采用改变管柱组合、调整工具下入顺序、加入双向减震器、分段延时射孔等技术,建立了超深探井测试管柱安全控制措施。以LX1井为例,实测了管柱震动加速度,上、下高速压力计实测上、下峰值分别为100、150 m/s^(2)和60、80 m/s^(2),相差40%~50%,说明双向减震器可以起到减震降损的作用。经多口超深井探井现场应用,验证了安全控制措施的可靠性。

In domestic ultra-deep well testing,the perforation-testing combined process is utilized.However,in ultra-deep wells with small boreholes,issues such as bending and fracture of the lower part of the casing and the center tube of the isolation packer are prone to occur.Based on the gas Clapeyron equation and detonation gas energy formula,we derived a calculation formula for maximum peak pressure at the bottom of the well and at the isolation packer due to perforation detonation.Additionally,using tubular string bending mechanics theory and material bending theory,we derived a calculation formula for bending stress in perforated section tubular strings.By combining piston effects from peak pressures,we also derived a stress calculation formula for tubular strings under impact loads to assess their strength safety.Building upon results from mechanical analysis of perforated section tubular strings,technical measures were established for safe control of test tubular strings by altering string combinations,adjusting tool insertion sequences,adding bidirectional shock absorbers,and implementing segmented delayed perforations.Taking LX1 well as an example:measured acceleration of tubular string vibration was 100 m/s^(2)(upper)and 60 m/s^(2)(lower),while high speed pressure gauge measurements showed upper peaks at 150 m/s^(2) and lower peaks at 80m/s^(2)-indicating a difference between them ranging from 40%to 50%.This demonstrates that bidirectional shock absorbers can effectively reduce vibration-induced losses.After being applied across multiple ultra-deep well exploration sites these measures have been validated for reliability in ensuring safety controls.