高石梯-磨溪区块高压气井尾管固井技术

针对西南油气田高石梯-磨溪区块高压气井φ177.8 mm尾管固井遇到的气层活跃、安全密度窗口窄、流体相容性差及高温大温差等问题，制定了相应的固井技术措施。开发了适合高温大温差固井的自愈合防窜高密度水泥浆体系，并进行了室内研究。结果表明:该体系密度为2.0~2.8 g/cm3，现场一次混配可达2.6 g/cm3以上；适应温度为常温~180℃；浆体的上下密度差不大于0.05 g/cm3；失水量不大于50 mL；稠化时间与缓凝剂掺量具有良好的线性关系，稠化过渡时间不大于10 min；静胶凝强度过渡时间不大于20 min；24 h抗压强度大于10 MPa，水泥石顶部48 h抗压强度大于3.5 MPa，低温下强度发展快，形成的水泥石体积稳定不收缩，具有类似韧性水泥的力学性能；遇油气产生体积膨胀，保证了界面胶结质量和密封完整性，降低了固井后发生气窜的风险。该固井技术在高石X井和高石Y井中进行了应用，固井优质率和合格率得到较大幅度提高，水泥环后期不带压，获得良好应用效果。 

Liner Cementing the high pressure gas wells in the Block Gaoshiti-Moxi

In cementing the φ177.8 mm liner string in high pressure gas wells in the Block Gaoshiti-Moxi of southwest oilfield, problems such as active gas zones, narrow drilling windows, poor compatibility of fluids and large temperature difference at high temperatures, were encountered. Technical measures were prepared to deal with these problems, and a self-healing anti-channeling high density cement slurry was developed for cementing wells with large temperature difference at high temperatures. Laboratory study of the cement slurry showed that the cement slurry had density between 2.0 g/cm3 and 2.8 g/cm3, and in field application, the cement slurry can be prepared to have a density of 2.6 g/cm3 in one mixing circulation. This cement slurry functioned at temperatures between room temperature and 180℃. Differences between the density of the top and bottom of cement slurry column was less than or equal to 0.05 g/cm3. The fluid loss of the cement slurry was less than or equal to 50 mL. The thickening time had good linear relationship with the concentration of retarders, and the transit time for the thickening of the cement slurry was not longer than 10 min. The maximum transit time of the gel strengths of the cement slurry was 20 min. The 24-hour compressive strength of the set cement was greater than 10 MPa, and the 48-hour compressive strength of the cement top was greater than 3.5 MPa. The strength of the cement slurry developed fast at low temperatures. The set cement formed had stable non-shrinking volume, possessing a mechanical performance that is similar to that of tough cement. The cement slurry expanded when in contact with oil and gas, ensuring the quality of bonding between cement sheath with casing string and borehole wall, and the integrity of sealing, which in turn mitigating the risk of gas channeling after cementing job. High quality of cementing job with this cement slurry was obtained in cementing the well Gaoshi-X and the well Gaoshi-Y, with no pressure developed in the annular space after cementing.