Magnetic and mineralogical characteristics of reservoir rocks in the Yakela oil field, northern Ta rim Basin and their implications for magnetic detection of oil and gas accumulations

The evidence about hydrocarbon migration within reservoir rocks in two wells has been obtained according to results of magnetic and mineralogical analysis of the Kapushaliang Group reservoir rocks from wells S15 and S4 located at the Yakela oil field, Tarim Basin. Results show that the secondary alteration associated with oil and gas accumulations above oil and gas field is predominantly magnetite mineralization, and that sulfur alteration occurs commonly at oil-water boundary and their products are generally pyrite and pyrrhotite, except for magnetite alteration which is closely related with hydrodynamical conditions in situ. The spherical magnetite grains of cauliflower microtexture on surface extracted from oil-bearing cores are secondary magnetite related with hydrocarbon microseep-age and their diameters are usually less than 50 μm.     

岩石超声谐波特征及其随应力的变化

岩石具有较强的非均质性和强衰减特性,谐波测量的难度较大。建立超声谐波测试实验系统,采用单频脉冲串(tone burst)激发、门控放大、脉冲反转和叠加等增强二次及高次谐波,研究岩石超声谐波的发育与振幅特征,定义名义非线性系数,分析单轴应力下岩石超声谐波及名义非线性系数随应力的变化。结果表明,超声谐波包含了丰富的岩石内部结构信息,表征了岩石的非线性特性,利用先进的仪器系统,采用谐波强化技术,可有效地获得岩石的超声谐波及其振幅,进行岩石非线性特性、微结构变化与损伤演化的监测。     

岩石复电阻率测量中的电极效应

复电阻率是电磁勘探描述地下岩石电性的重要参数之一。根据电磁勘探频段,实验室内复电阻率测量的低频段通常达到10~(-2) Hz。为避免测试电极与岩石的宏观结构形成电极极化影响岩石微观结构的研究,通过电化学理论结合复电阻率实验研究了不同电极材料对流体、岩石的复电阻率测试中的电极极化特性。结果表明,测试岩石在低频段容易受以物质传递为主的电极极化影响;电极极化同时受电极材料、电极附近流体矿化度和温度、被测岩石阻抗等因素的影响;最后,分析和讨论了减小或消除电极极化影响的方法,为准确测量岩石复电阻率并用于微观结构分析提供了理论和实验基础。     

裂隙发育对低孔低渗含气地层声传播特征的影响

在含孔、裂隙介质弹性波动统一理论的基础上,研究裂隙发育对低孔含气地层弹性波速度的影响。针对岩心测量的纵横波速度,探讨估算岩心裂隙密度的方法。结果表明:随着裂隙密度的增加,弹性波的速度降低明显;地震、测井和实验室岩心测量频率下的波速变化明显,显示出了较强的频散特性;在孔隙度为1.1%时,裂隙发育岩石在饱含气时的纵波速度与饱含水相比明显降低,裂隙密度为0.15和0.35时,500 kHz下的纵波速度分别下降了7.6%和27%;井孔模式波的衰减与速度相比对含气的敏感性更高,这为利用声波测井方法识别孔隙流体性质提供了思路。     

陆东凹陷后河地区下白垩统储层特征研究

从储层的岩石学特征、孔隙的类型和结构以及其物性等方面,对陆东凹陷后河地区下白垩统储层特征进行分析,认为储集层的成分和结构成熟度低。孔隙类型主要有残余原生粒间孔、次生孔、微孔隙和微裂缝四种,以次生孔为主要的储集空间,是油气主要的富集场所。孔喉以微细喉和特细喉为主,孔隙的连通性较差。储层孔隙大小分布不均,具有低孔、特低渗特性。沉积相带和成岩作用是影响储层物性的主要因素,次生孔隙带的发育与溶蚀作用关系密切。