注入甲醇抑制剂法开采神狐海域天然气水合物数值模拟研究

Numerical simulation of gas hydrate exploitation in the Shenhu Sea area by injecting methanol inhibitor

摘要:

我国神狐海域天然气水合物储量丰富，为我国提供了大量的能源储备，采用高效的开采方式能有效地解决我国能源短缺的问题。注入抑制剂法是一种主要的开采天然气水合物的方法。甲醇是一种性能优良的抑制剂，具有抑制性能好且粘度低的优点。本文根据实际地质参数建立了三维三相四组分开采海域天然气水合物数值模型，采用中间注入井两边生产井的水平井布井方式，通过数值模拟手段研究了注热甲醇溶液抑制剂法开采水合物的动态特征，与单一降压法和注入热水法的开采效果进行了对比。结果表明，注入热甲醇溶液能够提高储层温度并且甲醇能促进水合物的分解，改善了单一降压法和注热水法的不足，具有更高的初期产气速率，更高的初期气水比，以及更高的水合物分解效果，是一种具有竞争力的开采手段。

Abstract:

The gas hydrate reserve is abundant in the Shenhu Sea area， which provides a large amount of energy reserve for our country， and the problem of the shortage of energy can be solved effectively by means of efficient exploitation. Inhibitor injection method is one of the main methods to extract gas hydrate. Methanol is an excellent inhibitor with good inhibition and low viscosity. In this paper， a three-dimension， three-phase and four-component numerical model for gas hydrate exploitation in the sea area was established according to the actual geological parameters. The dynamic characteristics of hydrate exploitation in hydrothermal methanol solution were studied by means of numerical simulation using the horizontal well layout method with production wells on both sides and the injection well in the middle. The extraction effects of single depressurization method and hot water injection method were compared with that of the methanol inhibitor injection and the results show that the later can increase the reservoir temperature and promote the decomposition of hydrate， which improves the shortcomings of the former two methods. It has higher initial gas production rate， higher initial gas-water ratio and higher hydrate decomposition effect， which is a competitive exploitation method.