油藏压实、出砂引起的射孔段套损机理分析

Casing failure mechanism analysis induced by reservoir compaction and sand in the producing layer

产层出砂引起的套管弯曲是油田开采不容忽视的问题。为解决产层套管的弯曲问题,通过建立压实、出砂引起的弯曲套管的力学模型,来解释部分层段产生相对滑动以及弯曲的机理。从出砂产层套管损坏的机理出发,综合考虑几何、物理、静力学三方面作用,结合一些油田套管损坏的实际情况得出套管弯曲损坏的力学模式。利用华北地区某井实际资料对本模型的验证,证实了压实、出砂共同促成套管弯曲的情况,并取得了良好的模拟效果。结果表明:套管弯曲不仅使有效横截面降低而且由于局部拉应力过大造成套管拉断。因此有效防砂、优化套管设计等对防止套管弯曲,增加油田生产的总体经济效益有一定的指导意义。

Casing bend caused by sand inflow on the producing layer is a major problem in oilfield exploration. To solve the problem, this paper establishes a mechanical model of casing bend to explain the relative slipping and casing bend mechanism for some layer segments. Based on the mechanism of casing damage in the sand inflow layer, it takes the factors from geometry, physics and statics into account, analyzes some casing damage cases in the oilfield to deduce the mechanical model of casing bend and damage. The model has been validated by the practice data of a well in North China, which confirms that compacting and sand problems both result in casing bend. Good simulation effect has been achieved as well. Research results indicate that casing bend not only makes effective cross section decrease but also leads to casing snapping owing to larger local tensile stress. So effectively preventing sand and optimizing casing design is helpful to increase the overall economic results of oilfield production.