砂岩储层出砂段套管强度分析

Analyze of Production Casing Failure for Sand Production

砂岩储层开采过程中储层砂岩会与储层流体一起流向井筒,易在井筒附近油层形成出砂空洞,使储层出砂段套管失去地层的保护作用,引起套管失效。分析出砂段套管强度校核采用的圆柱壳屈曲模型理论的局限性,提出依据普氏理论,建立疏松砂岩出砂后套管的受力模型;并采用数值方法确定出砂段套管强度值。研究表明:出砂段空洞高度与套管轴向力呈一定线性比例,出砂段空洞与出砂量是一定指数关系。该理论可用来进行出砂段套管的校核和设计。

Loose sandstone reservoir improve oil recovery with reasonable sand control, but cavities around the wellbore are formed when sand is produced, which makes the casing lost the protection of the formation and casing failure comes about. Comparing with the limitation of thin cylindrical shell theory , a mechanical model of stable sand arch acting on casing when sand production is established by M. M. npoTo^bnKOI-IOB. It is found that strength failure is the main casing failure under sand arching action and casing ultimate strength calibration formula is given. The research shows the cavity height and sand production volume are in a power relationship; the cavity height and axial force are in a linear relationship. With the increase of the overburden pressure, the used he used higher steel grade to keep the reliability of the casing. The research provides theoretical foundation for production casing design and casing strength verify.