盐膏层TP140特厚壁套管抗挤特性研究

针对塔里木地区深层的盐膏层塑性流动性强，一般API套管难以满足要求的难题，以塔里木地区应用的TP140V特厚壁盐膏层套管为分析对象，建立了套管、水泥环、地层力学模型，运用有限元方法分析了特厚壁套管在非均匀载荷作用下的抗挤特性。研究表明，在相同非均匀载荷作用下，Φ273.1 mmTP140特厚壁套管较普通套管最大应力降低了36%，特厚壁套管具有更强的抵抗非均匀载荷的能力。但是随着载荷的非均匀程度升高，仍然可能导致套管损坏。因此，应该在有盐膏层的区域准确预测两向水平载荷的大小，为正确选用厚壁套管提供依据；水泥环厚度对套管抗挤性能的影响不大，故盐膏层井段的环空间隙大小均能满足固井质量要求即可。

COLLAPSE CHARACTERISTICS ANALYSIS FOR TP140 HEAVILY THICK WALL CASING

The deep gypsum rocks in Tarim area is characterized by high plastic fluidity, the common API casing can not meet the operation requirements. Taking the TP140V heavily thick wall casing used in Tarim as a case of study, this study built up the mechanical models for casing, cement sheath and formation, and by FEA method analyzed the collapse strength of the extra heavy wall casing under non uniform loads. The study showed that under the same non uniform loads the maximum stress produced on the 273.1 mm TP140 heavily thick wall casing is 30% lower than that on common casing, that is to say, the TP140 casing is better than common casing in terms of bearing non uniform loads. However, whatever casing is used, it will easily tend to collapse along with the increasing extent of non uniformity of the loads. So this paper suggests that the horizontal loads in gypsum formations should be accurately predicted to provide evidence for the proper use of heavily thick wall casing. As the thickness of the cement sheath does little to do with the casing collapse, so this paper puts forward work will be done well if the annulus clearance in gypsum section can meet the cementing requirements.