各向异性断块油藏水平井产能公式的推导

封闭性断块油藏在中国分布广泛,具有较多原始地质储量和剩余可采储量,因此评价断块油气藏水平井的产能方法具有重要意义。利用水电相似原理和等值渗流动阻力法,对于布井位置不同的断块油藏,在考虑油层渗透率各向异性条件下,得到了预测水平井产能的公式和水平井产量与水平井长度成正比的直线关系。通过应用实例表明,对于断块油藏,水平井布置在油层中央时的产能显著高于布置在边部的产能,这主要由于前者的流动阻力明显低于后者;不同垂向拟平面径向流的半径,对水平井产能的影响较小,且水平井的产能主要受控于线性流动区的阻力。     

页岩气藏水平测井裂缝识别及声学成像研究

随着中国西南地区页岩气水平井钻探与开发取得重要进展,页岩气藏水平井测井资料的处理与解释变得尤为重要。对四川焦石坝页岩气水平井的声波测井数据进行处理,分析页岩地层水平井井孔声场及远探测声场的传播特征,旨在对页岩气藏中的裂缝进行识别和评价,为地震波方位各向异性的成因提供佐证。利用四分量偶极声波测井数据进行横波各向异性处理,分别获得水平偏振(SH)和垂直偏振(SV)的横波数据及波速。在此基础上采用横波远探测技术进行井外反射体的成像处理。处理结果表明该井外地层存在与井斜交的垂直裂缝体系,与该地区的构造形态有关,该裂缝体系的存在与该井区页岩气的高产密切相关。处理结果为页岩气水平井声学测井数据提供了有效的处理方法和较好的应用前景。     

A methodology to determine the elastic properties of anisotropic rocks from a single uniaxial compression test

This paper introduces a new methodology to measure the elastic constants of transversely isotropic rocks from a single uniaxial compression test. We first give the mathematical proof that a uniaxial compression test provides only four independent strain equations. As a result, the exact determination of all five independent elastic constants from only one test is not possible. An approximate determination of the Young's moduli and the Poisson's ratios is however practical and efficient when adding the Saint–Venant relation as the fifth equation. Explicit formulae are then developed to calculate both secant and tangent definitions of the five elastic constants from a minimum of four strain measurements. The results of this new methodology applied on three granitic samples demonstrate a significant stress-induced nonlinear behavior, where the tangent moduli increase by a factor of three to four when the rock is loaded up to 20 MPa. The static elastic constants obtained from the uniaxial compression test are also found to be significantly smaller than the dynamic ones obtained from the ultrasonic measurements.     

Temperature dependent coercivity of randomly assembled acicular Fe3O4 particles

Abstract

The Stoner‐Wohlfarth model and the chain‐of‐spheres fanning model are used to calculate temperature dependence of the coercivity of acicular single‐domain particles by taking thermal effect into consideration. Coercivity of the particles is evaluated by summing up the contributions of shape anisotropy, magnetocrystalline anisotropy and magnetostrictive anisotropy. The coercivities of randomly assembled Fe₃O₄ particles above the transition point (119°K) and below room temperature are calculated and compared with the published experimental data.     

Magnetocaloric effect in Gd(1−y)DyyAl2

In this work we calculate the magnetic properties and the magnetocaloric effect in Gd_1−yDy_yAl₂ (y = 0, 0.25, 0.5, 0.75 and 1). The model Hamiltonian includes contributions from the Zeeman effect, the crystalline electrical field anisotropy and the exchange interactions among Gd–Gd, Gd–Dy and Dy–Dy ions. To obtain a composite with ΔS_T as constant as possible in the temperature range from T = 60 K to 170 K, the appropriate concentrations of the five compounds investigated were calculated using the Smaili and Chahine method. The magnetization and ΔS_T dependences on temperature in the composite were simulated and compared with the partial contributions of the single magnetic component materials. Also, the magnetic field dependence on magnetization was investigated in Gd_0.25Dy_0.75Al₂, where the discontinuous spin reorientation transitions were predicted for magnetic fields lower than 2 T, applied along <110> direction.