基于成像测井的页岩气储层可压裂性评价方法研究

Due to the low porosity,permeability and strong heterogeneity of the shale gas reservoir, resulting in the fracturing difficulties. Thus, there is an urgent need to carry out a prospective study for the evaluation and optimization of the fracturing layer selection and fracturing design. First, the research of logging response characteristics of shale reservoirs will be carried out, starting from the core physical experimental,large-scale logging rocks division and small-scale mineral components analysis will be combined to establish the shale reservoir lithofacies and lithology evaluation methods. Secondly, the T2 spectrum from inversion of of NMR logging T2 spectrum will be simulated to of the capillary pressure curve, developed based on magnetic resonance imaging logging shale fracturing sexual pores structural capacity evaluation methods. Then based on the core calibration and the conventional logging constrained, the borehole image data will be used to research the shale fracture genetic mechanism, fracture type identification, fracture extended direction and the shale reservoir fracture evaluation methods will be established. Based on array sonic logging data to carry out shale rock mechanics parameters model, the stress computation model and the establishment of rocks static and dynamic parameter transformation model, then the formation fracture pressure and fracturing height will be predicted, finally the shale gas reservoir fracturing design optimization parameters will be provided. Ultimately a shale gas reservoir fracturing of the Comprehensive logging evaluation methods will be developed.

由于页岩气储层低孔渗、非均质性强等特性，造成压裂实施困难，迫切需要针对压裂选层评价和优化压裂设计开展前瞻性的研究。首先从岩心物理实验刻度测井信息出发，研究页岩储层的测井响应特征，以大尺度测井岩相划分与微小尺度矿物组分分析相结合的手段，建立泥页岩储层可压裂性的岩相、岩性评价方法；其次，对核磁测井回波串反演的T2谱数值模拟出毛管压力曲线，研究出基于核磁共振成像测井的泥页岩可压裂性的孔隙结构产能评价方法；然后利用图像处理方法，对岩心刻度、常规测井约束后的成像测井资料，进行泥页岩裂缝成因机理、裂缝类型识别、裂缝延展方向的确定研究，建立泥页岩储层可压裂性的裂缝评价方法；同时基于阵列声波测井资料，开展泥页岩岩石力学参数计算模型和地应力计算模型研究，建立岩石动静态参数转换模型，进而预测地层破裂压力和压裂高度，为页岩储层的优化压裂设计提供必需的基础参数；最终形成一套页岩气储层可压裂性的综合测井评价方法。

泥页岩储层具有岩性复杂、低孔低渗、非均质性强等特征，为能实现高效开发有必要对储层的可压裂性评价方法开展深入研究。本项目以XX地区下寒武统牛蹄塘组海相页岩和LJ地区沙三下-沙四上陆相页岩为研究对象，通过岩心和薄片观察、物性测试、压汞、核磁共振和岩石力学性质测试等实验，结合测录井和测试分析资料，从岩性（岩相）、孔隙结构、裂缝、岩石力学四个方面综合开展了页岩气（油）储层可压裂性的测井评价方法研究，最终形成了一套泥页岩储层可压裂性测井评价的软件。.研究结果表明，沙河街组陆相页岩岩性及岩相较为复杂，从沉积构造的角度主要划分为纹层状、层状和块状构造，结合岩性主要可分出八种不同类型，通过岩心刻度成像测井、成像测井标定常规测井和交会图版与神经网络预测相结合的手段，建立了泥页岩岩性及岩相的响应模式和识别方法，结合现场测试分析得出层状泥质灰岩可压裂性最好，块状泥质灰岩及灰质泥岩最差；牛蹄塘组海相页岩主要分为灰岩、泥岩、页岩、粉砂质泥岩、硅质泥岩和硅质页岩，而可压裂性最好的是硅质页岩。牛蹄塘组页岩孔隙度分布在1%-3%之间，微观孔径主要分布在0.01-10μm，主要发育矿物粒间孔和粒内孔，陆相沙河街组页岩孔隙微小，类型主要为粘土矿物晶间微孔、方解石晶间孔，通过核磁T2谱构建了伪毛管压力曲线新模型，结合岩心和CT扫描电镜实验反演储层孔隙结构，得出尺度一般大于1.0μm的微裂缝发育段页岩储层可压裂性能较好。从页岩天然裂缝形态、裂缝成因和诱导缝建立了电成像测井图像响应模式，基于小波高频属性方法能够较好地识别出泥页岩裂缝。总结出影响页岩可压裂性的因素有岩石脆性、脆性矿物含量、有机碳含量、粘土矿物含量、断裂韧性和水平地应力差等，采用层次分析法建立了泥页岩储层可压裂性评价指数，通过压裂段的微地震监测结果对可压裂性评价进行了验证。该套泥页岩储层可压裂评价方法及软件为泥页岩储层可压裂评价研究提供一种借鉴，具备一定的推广价值。