高压深层井段地层岩性对固井质量影响研究

Effects of Formation Lithology on Cementing Quality in High Pressure Deep Section

在固井施工中,由于多种因素的影响,固井质量总不够理想,特别在高压深层井段问题更为严重。为此,采用自行研制开发的JHT-02高温高压固井质量评价仪(物理模型按10∶1缩小,并制作了相应的缩小换能器),模拟高压深层井段不同孔隙度与渗透率的砂岩与泥岩,进行了水泥与不同岩性地层胶结性能的试验,对比试验结果及现场测井曲线,发现:对于深井中存在异常高压的井段,地层岩性和孔渗性能影响水泥与地层的胶结强度,随着孔渗性能的变化,水泥与泥岩和砂岩地层的胶结强度变化规律一致,随孔隙度与渗透率的增加胶结强度下降;在高压常温环境下,水泥与砂岩地层的胶结强度要低于水泥与泥岩地层的胶结强度;对于相同渗透率的泥岩地层,高压带较低压带胶结更理想;建议在高压常温井段选择合适的钻井液体系,防止水泥浆在高渗地带过多失水,以提高固井质量。

The cementing qualities are always not satisfactoring due to different reasons during cementing works, especially in the high pressure deep wells. Therefore, a HPHT cementing quality evaluation equipment, JHT-02 （the physical model with a scale ratio of 10 ： 1 and the associated converter） was developed. The cementation quality experiments testing cement with different formation lithology were examined in the simulated high pressure deep well in sandstone or shale with different porosity and permeability. Comparison with the well logging curves indicates that, for the deep well with high pressure section, formation lithology and porosity impact the cement quality, with the changing of the porosity or permeability, the changes of the cementing strength of cement with sandstone and cement with shale are similar. The cementing strength is decreasing with the increase of porosity or permeability. Cementing strength of the cement with sandstone is lower than that of cement with shale. For the shale with same permeability, cement quality in higher pressure is better than that in lower pressure. It suggested that a suitable drilling mud was used in HPHT to prevent dehydration of slurry and to improve the cementing quality.