鄂尔多斯盆地陇东地区太原组铝土岩跨频段岩石物理实验及认识  

Cross-frequency band petrophysical experiments and understandings on Taiyuan Formation bauxite in the Longdong area of the Ordos Basin

作　　者：李斐 闫国亮[3] 杜广宏[1,2] 高建虎[3] 张盟勃[1,2] 赵万金[3] 佘钰蔚[1,2] 何润 瞿长 LI Fei;YAN Guoliang;DU Guanghong;GAO Jianhu;ZHANG Mengbo;ZHAO Wanjin;SHE Yuwei;HE Run;QU Chang(National Engineering Laboratory of Low-Permeability Oil&Gas Exploration and Development,Xi'an,Shaanxi 710018,China;Exploration and Development Research Institute,PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China;PetroChina Research Institute of Petroleum Exploration&Development-Northwest,Lanzhou,Gansu 730020,China)

机构地区：[1]低渗透油气田勘探开发国家工程实验室 [2]中国石油长庆油田公司勘探开发研究院 [3]中国石油勘探开发研究院西北分院

出　　处：《天然气工业》2024年第7期77-88,共12页Natural Gas Industry

基　　金：中国石油天然气集团公司科技项目“多波场地震成像与弹性参数同步反演理论与技术”(编号:2023ZZ05-02);甘肃省科技重大专项“陇东地区天然气藏地球物理预测关键技术研发及应用”(编号:23ZDGA004);中国石油长庆油田公司项目“多尺度跨频带岩石物理测试分析”(编号:CQYT-CQKTY-2023-JS-2834)。

摘　　要：鄂尔多斯盆地西南部陇东地区二叠系太原组铝土岩天然气勘探已实现突破,多口探井获得高产工业气流,铝土岩天然气勘探成为该区热点领域。但针对该区铝土岩频散特征的基础研究尚未开展,为了进一步探索铝土岩的地震波频散特征及其油气勘探意义,通过跨频段实验分析了太原组铝土岩的岩石物理特性,明确了铝土岩的频散特征,并运用改进的Gurevich喷射流模型解释了实验结果。研究结果表明:①铝土岩主要矿物成分为—水硬铝石和黏土矿物,储集空间类型主要包括粒内溶蚀孔洞、晶间溶孔和微裂缝,储层类型为裂缝—孔隙型储层,孔隙度为0.2%~28.7%,平均值为10.7%,渗透率为0.004~38.550 mD,平均值为4.040 mD,储层物性条件好;②孔隙度大小是决定含铝岩石频散特征的主要因素之一,饱和水铝土岩和铝土质泥岩均存在频散现象,孔隙度较高的铝土岩样品频散特征明显强于孔隙度较低的样品,1~10 Hz范围内频散特征较强;③孔隙度是影响岩石压力敏感性的主要因素之一,高孔隙度铝土岩样品随着压力增加,超声波测试的纵波速度与低频应力—应变计算的速度相近,纵波速度变化范围超过700 m/s,远大于低孔隙度样品;④含水饱和度与超声波速度之间呈现震荡变化关系,存在多个局部极值点。结论认为:①高孔隙度铝土岩样品速度测试结果与频散理论模型计算结果一致,而低孔隙度样品频散主要出现在10 Hz以上,超声频段实验结果与频散理论模型计算结果不符;②通过跨频段实验探索了铝土岩的频散岩石物理特征,为采用频散理论预测铝土岩储层分布及含气性奠定了理论基础。Breakthroughs have been achieved in natural gas exploration in the Permian Taiyuan Formation bauxite in the Longdong area of the southwestern Ordos Basin,with several exploratory wells obtaining high-yield industrial gas flows.This has made bauxite natural gas exploration of this area a hot field.So far,however,the basic studies have not been conducted on the dispersion characteristics of bauxite in this area.To further investigate the seismic wave dispersion characteristics of bauxite and their implications for oil and gas exploration,this paper carries out cross-frequency band experiments to analyze the petrophysical properties of the Taiyuan Formation bauxite,and clarifies the dispersion characteristics of bauxite.In addition,the experimental results are verified using the improved Gurevich jet flow model.And the following research results are obtained.First,the main mineral components of bauxite are diaspore and clay minerals,and the storage space types mainly include intragranular dissolution pores,intercrystalline dissolution pores and microfractures,which constitute fractured-porous type reservoirs with the porosity ranging from 0.2%to 28.7%and averaging 10.7%,and the permeability ranging from 0.004 mD to 38.550 mD and averaging 4.040 mD,indicating favorable physical properties of reservoirs.Second,the value of porosity is one of the primary factors determining the dispersion characteristics of aluminiferous rocks.Both water-saturated bauxite and bauxitic mudstone exhibit dispersion phenomena.The dispersion characteristics of bauxite samples with higher porosity are significantly stronger than those with lower porosity,particularly in the 1-10 Hz range.Third,porosity is one of the main factors affecting the pressure sensitivity of rocks.With the increase of pressure,the measured ultrasonic compression wave velocity of high-porosity bauxite samples is close to the velocity calculated using low-frequency stress-strain,and its change range exceeds 700 m/s,which is significantly greater than that of low-porosi

关 键 词：鄂尔多斯盆地 太原组 铝土岩 岩石物理 跨频段 频散 

分 类 号：TE135[石油与天然气工程—油气勘探]