深层页岩储层裂缝识别及有效性评价方法研究及应用——以四川盆地南部为例

四川盆地南部地区(以下简称川南)深层页岩储层断裂发育,直接影响页岩气水平井的工程施工和有效建产。基于川南五峰组—龙马溪组页岩岩心,开展岩石物理实验和数值模拟实验,得到了不同尺度、不同产状、不同充填物质的裂缝声学响应特征,分析了裂缝对声波衰减能力的影响因素,建立了1套页岩气水平井裂缝识别和有效性评价方法。结果表明:纵波、横波和斯通利波的振幅衰减受裂缝倾角和裂缝宽度的共同影响,其衰减能力随裂缝宽度增加呈指数增加,随裂缝倾角的增加而降低。斯通利波对充填流体裂缝敏感,可识别和评价含气、含水的有效裂缝;纵波和偶极横波对充填方解石裂缝敏感,可识别和评价充填方解石的无效裂缝。基于反射波成像识别的裂缝结果与成像测井、岩心识别裂缝类型一致,验证了有效性评价方法的可靠性。将研究成果应用于页岩气水平井实测资料,精细评价了页岩气水平井断裂风险位置,有效保障了“一段一策”压裂分段的优化设计。

淮河文化概念之界说

与许多地域文化相比,淮河文化更加复杂而不易把握,这是由于多种因素所决定的,其中淮河文化本身"大象无形"的特点可能较关键。因此,讨论淮河文化概念,首要的工作在于找到认知淮河文化特质的恰当方式,与综合各学科各方面的研究成果从而加以概括的方法。通过多层面多角度的探究,我们尝试着给淮河文化一个初步的概括,主要包括四个方面的内容,而平原文化的特质是为淮河文化基本的或主体的方面。

TeachingmA Way of Implementing Statistical Methods for Ordinal Data to Researchers

The use of questionnaires, rating scales and other kinds of ordered classifications is unlimited and interdisciplinary, so it can take long time before novel statistical methods presented in statistical journals reach researchers of applied sciences. Therefore. teaching is an effective way of introducing novel methods to researchers at an early stage. Assessments on scales produce ordinal data having rank-invariant properties only, which means that suitable statistical methods are non-parametric and often rank-based. These limited mathematical properties have been taken into account in the research regarding development of statistical methods for paired ordinal data. The aim is to present a statistical method for paired ordinal data that has been successfully implemented to researchers from various disciplines together with statisticians attending interactive problem solving courses of biostatistics.

The Application of a Small Strain Model in Excavations

The importance of soil small strain effect on soil-structure behavior was investigated by researchers in last decades. The finite element method （FEM） is always used to predict the excavation behavior, whereas there are not many soil models available to consider this effect in analysis. This paper introduces a simple small strain soil model--hardening small-strain （HSS） in PLAXIS 8.5 and exhibits its application in excavation problems via studying the history of two cases. The analyses also use two familiar soil models： hardening-soil （HS） model and Mohr-Coulomb （MC） model. Results show that the HSS predicts more reasonable magnitudes and profiles of wall deflections and surface settlements than other models. It also indicates that the small strain effect relies on the strain level which is induced by excavation.

Numerical study on two-phase flow through fractured porous media

Based on the flux equivalent principle of a single fracture, the discrete fracture concept was developed, in which the macroscopic fractures are explicitly described as （n-l） dimensional geometry element. On the fundamental of this simplification, the discrete-fractured model was developed which is suitable for all types of fractured porous media. The principle of discrete-fractured model was introduced in detail, and the general mathematical model was expressed subsequently. The fully coupling discrete-fractured mathematical model was implemented using Galerkin finite element method. The validity and accuracy of the model were shown through the Buckley-Leverett problem in a single fracture. Then the discrete-fractured model was applied to the two different type fractured porous media. The effect of fractures on the water flooding in fractured reservoirs was investigated. The numerical results showed that the fractures made the porous media more heterogeneous and anisotropic, and that the orientation, size, type of fracture and the connectivity of fractures network have important impacts on the two-phase flow.

Numerical study of detonation shock dynamics using generalized finite difference method

The generalized finite difference method (GFDM) used for irregular grids is first introduced into the numerical study of thelevel set equation, which is coupled with the theory of detonation shock dynamics (DSD) describing the propagation of thedetonation shock front. The numerical results of a rate-stick problem, a converging channel problem and an arc channel prob-lem for specified boundaries show that GFDM is effective on solving the level set equation in the irregular geometrical domain.The arrival time and the normal velocity distribution of the detonation shock front of these problems can then be obtainedconveniently with this method. The numerical results also confirm that when there is a curvature effect, the theory of DSDmust be considered for the propagation of detonation shock surface, while classic Huygens construction is not suitable anymore.

Numerical study on flexural behaviors of steel reinforced engineered cementitious composite(ECC) and ECC/concrete composite beams

Engineered cementitious composite(ECC)is a class of high performance cementitious composites with pseudo strain-hardening behavior and excellent crack control capacity.Substitution of concrete with ECC can largely reduce the cracking and durability problems associated with brittleness of concrete.In this paper,a simplified constitutive model of the ECC material was applied to simulate the flexural behaviors of the steel reinforced ECC and ECC/concrete composite beams with finite element method.The simulation results are found to be in good agreement with test results,indicating that the finite element model is reasonably accurate in simulating the flexural behaviors of the steel reinforced ECC flexural members.The effects of the ECC modulus,ECC tensile ductility,ECC thickness and ECC position on flexural behaviors in terms of ultimate moment,deflection and the maximum crack width of the steel reinforced ECC or ECC/concrete composite beam are hence evaluated.