Stress determination from hydraulic fracturing tests : the system stiffness approach
Stress determination from hydraulic fracturing tests : the system stiffness approach
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DOI：
10.1016/s1365-1609(01)00020-x
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发表时间：
2001-06
影响因子：
7.2
通讯作者：
A. Raaen;E. Skomedal;H. Kjørholt;P. Markestad;D. Økland
中科院分区：
文献类型：
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作者：
A. Raaen;E. Skomedal;H. Kjørholt;P. Markestad;D. Økland
泥浆水压致裂试验是确定深层石油威尔斯井中最小水平应力的最经济的方法。本文提出了一种泵入/关井和泵入/返排试验的统一模型。该模型的关键元素是由加压流体体积的刚度引起的系统刚度，以及由于断裂引起的刚度。结果表明，在这两种试验中观察到的断裂闭合时的系统刚度的变化。该模型直接用于设计和解释的回流测试，其中直接测量压力与回流体积，因此系统刚度是可能的。然而，该模型还预测了压力的时间发展，并建议了用于分析返排和关井测试的压力-时间曲线的方法。我们认为，在一个关井测试的压力-时间曲线的特点，泥浆可能会显着影响的泥饼，这是在渗透性地层的表面上形成的低渗透性。这使得传统的解释程序无效，使得本文中概述的新分析方法对于成功解释此类测试是必要的。模型计算得到了挪威近海大量现场数据的支持。
Hydraulic fracturing tests with mud is the most inexpensive method for determining the minor in situ horizontal stress in deep petroleum wells. This paper presents a unified model of pump-in/shut-in and pump-in/flowback tests. The key element of the model is the system stiffness resulting from the stiffness of the fluid volume pressurised, and the stiffness due to the fracture. It is shown that the change in system stiffness at fracture closure is observed in both kinds of tests. The model is used directly in the design and interpretation of the flowback tests, where direct measurement of pressure versus flowback volume, and hence system stiffness is possible. However, the model also predicts the time development of pressure, and suggests methods for the analysis of the pressure versus time curve for both flowback and shut-in tests. We argue that the character of the pressure versus time curve in a shut-in test with mud may be significantly influenced by the low permeability of the mud cake which is formed on the face of permeable formations. This invalidates the traditional interpretation procedures, making new analysis methods outlined in the paper necessary for a successful interpretation of such tests. The model calculations are supported by extensive field data from offshore Norway.