A system and method for optimizing and evaluating wellbore string materials in high-acidity gas fields

Abstract

The invention provides a high-acidity gas field wellbore string material optimization evaluation system and method, and belongs to the field of high-acidity gas field development. The high-acidity gas field wellbore string material optimization evaluation system includes a corrosion rate prediction model and a stress corrosion cracking boundary model; the corrosion rate prediction model includes H2S partial pressure-temperature, H2S partial pressure-CO2 partial pressure and elementary substance S-pH value corrosion rate prediction drawing boards; the stress corrosion cracking boundary model includes a failure boundary of a material under conditions of the temperature and the H2S partial pressure and a failure boundary of the material after sulfur is separated out under the conditions of the temperature and the H2S partial pressure. The system and the method solve the problems that due to a corrosion simulation evaluation method and a corrosion prediction model and software, a gas field highly containing H2S / CO2 is lack of basis on material selection, and provide a theoretical support for high-acidity gas field development and safety production.

Description

technical field [0001] The invention belongs to the field of high-acid gas field development, and in particular relates to a system and method for optimizing and evaluating wellbore string materials in high-acid gas fields. Background technique [0002] Marine basins have always been the main areas for oil and gas exploration and development in my country. Especially in recent years, with the improvement of oil and gas exploration in basins, the deepening of geological understanding, and the continuous improvement of exploration technology, Puguang, Yuanba, Dawan, Luojiazhai, Tieshan, Dukouhe, Tieshanpo and other gas reservoirs. These gas reservoirs have large effective reservoir thickness, high single well production, high hydrogen sulfide content, and large reserve scale. [0003] Due to the deep burial and high H content of marine gas reservoirs 2 S and CO 2 characteristics, its development process will face many international technical problems. During the production ...

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Problems solved by technology

[0007] 1. During the mining process due to H 2 The existence of S may form sulfur deposits in the wellbore. Once sulfur deposits are formed during production, it will cause serious damage to block the flow channel or corrode the wellbore materials, and even make the production well scrapped. At present, in the process of mining, it is impossible to It is difficult to judge whether sulfur deposits will be formed in the wellbore; it is difficult to judge the location of sulfur deposits; it is difficult to predict the change of gas components along the wellbore; 2 S / CO 2 The law of multiphase flow in gas field wellbore is unknown

[0008] 2. Previous corrosion evaluation methods cannot simulate high H in the laboratory 2 S partial pressure (>3.5MPa) conditions, and the corrosion evaluation experiment carried out by simulating the field environment cannot predict the long-term service performance of the material, and there is a lack of evaluation methods for sulfur deposition corrosion

[0009] 3. Corrosion research on materials in highly acidic gas field environments started late at home and abroad, and corrosion prediction models and software that can be directly used on site have not yet been formed

General corrosion evaluation models and failure discrimination methods are unable to analyze and judge the safety of materials in high acid gas field environment and carry out risk analysis

[0010] At present, there are no means and methods for systematically analyzing the optimal design of wellbore strings in high acid gas fields at home and abroad.

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