提高水泥层间封隔能力的低密度弹性密封水泥浆性能评价
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1.中海油研究总院有限责任公司;2.长江大学非常规油气湖北省协同创新中心;3.荆州嘉华科技有限公司

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Performance evaluation of low density elastic sealing cement slurry to improve the sealing capacity between cement layers
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    摘要:

    现有的固井水泥浆技术条件下,保障井筒完整性长期稳定面临挑战,尤其是常规低密度水泥浆,射孔后水泥石的完整性遭到破坏更严重,造成密封失效,水泥石与套管及井壁间的胶结质量差,易发生窜槽等问题。针对上述问题,优选了复配液体纤维使用来提高水泥石的强度和韧性,纳米减轻剂改善水泥浆沉降稳定性,优选10%加量的RES-1弹性材料降低水泥石的弹性模量,提高水泥石形变能力。室内对低密度弹性密封水泥浆展开了综合性能评价,结果显示:1.5g/cm3低密度弹性密封水泥浆体系具有良好的流变性,水泥浆稠化时间可调,失水量小于50mL,线性膨胀率达到0.45%,可有效抑制微环隙、微间隙的产生。较普通低密度水泥浆,低密度弹性密封水泥浆的渗透率和弹性模量分别降低了69.5%、78.4%,抗压强度和抗折强度分别提高了61%和54%,说明该水泥浆具有较好的致密性,柔韧性和弹性形变能力。水泥环封隔能力评价发现:低密度弹性密封水泥环在交变压力范围为20MPa-40MPa,升降压力频率5次条件下,模拟封固中的抗窜强度都大于7 MPa/m2,可以有效提高水泥环的长效封隔能力,改善固井质量。

    Abstract:

    Abstract: Under the existing cementing slurry technology, ensuring the long-term stability of wellbore integrity is facing challenges, especially the conventional low-density slurry. After perforation, the integrity of cement stone is damaged more seriously, resulting in sealing failure, poor cementing quality between cement stone and casing and well wall, and channeling is easy to occur. In view of the above problems, it is preferred to use compound liquid fiber to improve the strength and toughness of cement paste, nano lightening agent to improve the settlement stability of cement slurry, and 10% res-1 elastic material is preferred to reduce the elastic modulus of cement paste and improve the deformation capacity of cement paste. The comprehensive performance evaluation of low-density elastic sealing cement slurry was carried out in the laboratory. The results show that the 1.5g/cm3 low-density elastic sealing cement slurry system has good rheology, adjustable thickening time of cement slurry, water loss less than 50ml, and linear expansion rate of 0.45%, which can effectively inhibit the generation of micro annulus and micro gap. Compared with ordinary low-density cement slurry, the permeability and elastic modulus of low-density elastic sealing cement slurry are reduced by 69.5% and 78.4% respectively, and the compressive strength and flexural strength are increased by 61% and 54% respectively, indicating that the cement slurry has good compactness, flexibility and elastic deformation ability. The evaluation of the sealing capacity of the cement sheath shows that under the conditions of alternating pressure range of 20mpa-40mpa and pressure rise and fall frequency of 5 times, the anti channeling strength in the simulated sealing is greater than 7 MPa/m2, which can effectively improve the long-term sealing capacity of the cement sheath and improve the cementing quality.

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  • 收稿日期:2021-11-06
  • 最后修改日期:2021-12-15
  • 录用日期:2021-12-22
  • 在线发布日期: 2022-04-06
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