Investigations of Mechanical Properties of API P110 Steel Casing Tubes Operated in Deep-Sea Sour Condensate Well Conditions

Yao Zilin,Zhang Rong,Wang Yu,Yang Xuefeng,Gao Anping,Jia Yanjie

doi:10.2478/pomr-2020-0053

Yao Zilin, Zhang Rong + Show 4 more

Open Access

https://doi.org/10.2478/pomr-2020-0053

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Abstract

Abstract Due to the complexity of the marine environment, in deep-sea drilling, all kinds of strings are corroded by different deep-sea conditions for a long time, accompanied by high temperature and high pressure, which lead to the continuous change of mechanical properties of materials. In order to solve the problem that the material mechanical parameters cannot be accurately described in the performance analysis of the casing, deep-sea simulated corrosion and material damage experiments of P110 material were carried out in this paper. Mass loss and tensile experiments on corrosion-damaged test pieces were conducted under different corrosion experimental periods. The changes in mechanical properties of the material were analyzed. Equations of the variation of the equivalent yield strength and the equivalent tensile strength were obtained. The results show that the equivalent yield strength and the equivalent tensile strength decrease with the increase of the weight loss rate. Based on the experimental results and finite element analysis, a method for establishing the material corrosion model was proposed in this paper. The deep-sea drilling corrosion performance model of P110 material was established, which greatly reduced the error caused by the material uniformity assumption in finite element analysis. This paper provides a theoretical basis for the analysis of reliability and life of P110 materials in wells.

Highlights

With the gradual expansion of global offshore oil and gas field development, the damage of downhole strings becomes more and more serious with the increase of the service cycle
According to the test results, without considering the influence of corrosion on the area of the test piece, the equivalent yield strength and the equivalent tensile strength of the material after corrosion were calculated by the tensile test data
The mechanical property ratio of the material before and after corrosion was calculated in Table 6.It can be seen from Table 6 that when the weight loss rate was less than 15%, the equivalent yield strength and the equivalent tensile strength decrease with the increase of the weight loss rate

Summary

Introduction

With the gradual expansion of global offshore oil and gas field development, the damage of downhole strings becomes more and more serious with the increase of the service cycle. In this paper, based on deep-sea oil and gas wells, the degree of casing corrosion is directly expressed by the P110 weight loss rate obtained by corrosion damage experiment. In the analysis of the results of the second experiment, the average weights of the three unthreaded tensile test pieces before the experiment were 34.254, 34.662, and 34.558 g, respectively.

Results

Conclusion