Prediction of methane adsorption content in continental coal-bearing shale reservoir using SLD model

Shale gas, as an important unconventional resource, has drawn global attention. It is mainly composed of adsorption gas and free gas. Adsorption gas content could play an important guiding role on both the selection of favorable perspective area and the exploration and exploitation of shale gas resources. In order to accurately measure adsorption gas content, a new approach was established to predict the adsorption isotherm of methane on shale. Based on the simplified local-density (SLD) method, both the adsorption isotherms of illite, illite/smectite mixed-layer, cholorite and type III kerogen and the total shale rock could be well fitted. The fitting results show good coincidences with the true experimental test data, which proves the method is reasonable and dependable and the prediction results are effective and credible. In addition, the good simulation results show that the SLD parameters can reflect the pore structure characteristics and corresponding adsorption characteristics of the shale samples, which can be used for the quantitative characterization of shale pore system.     

PETROLEUM POTENTIAL, THERMAL MATURITY AND THE OIL WINDOW OF OIL SHALES AND COALS IN CENOZOIC RIFT BASINS, CENTRAL AND NORTHERN THAILAND

Oil shales and coals occur in Cenozoic rift basins in central and northern Thailand. Thermally immature outcrops of these rocks may constitute analogues for source rocks which have generated oil in several of these rift basins. A total of 56 oil shale and coal samples were collected from eight different basins and analysed in detail in this study. The samples were analysed for their content of total organic carbon (TOC) and elemental composition. Source rock quality was determined by Rock‐Eval pyrolysis. Reflected light microscopy was used to analyse the organic matter (maceral) composition of the rocks, and the thermal maturity was determined by vitrinite reflectance (VR) measurements. In addition to the 56 samples, VR measurements were carried out in three wells from two oil‐producing basins and VR gradients were constructed. Rock‐Eval screening data from one of the wells is also presented. The oil shales were deposited in freshwater (to brackish) lakes with a high preservation potential (TOC contents up to 44.18 wt%). They contain abundant lamalginite and principally algal‐derived fluorescing amorphous organic matter followed by liptodetrinite and telalginite (Botryococcus‐type). Huminite may be present in subordinate amounts. The coals are completely dominated by huminite and were formed in freshwater mires. VR values from 0.38 to 0.47%R_o show that the exposed coals are thermally immature. VR values from the associated oil shales are suppressed by 0.11 to 0.28%R_o. The oil shales have H/C ratios >1.43, and Hydrogen Index (HI) values are generally >400 mg HC/g TOC and may reach 704 mg HC/ gTOC. In general, the coals have H/C ratios between about 0.80 and 0.90, and the HI values vary considerably from approximately 50 to 300 mg HC/gTOC. The HI_max of the coals, which represent the true source rock potential, range from ～160 to 310 mg HC/g TOC indicating a potential for oil/gas and oil generation. The steep VR curves from the oil‐producing basins reflect high geothermal gradients of ～62°C/km and ～92°C/km. The depth to the top oil window for the oil shales at a VR of ～0.70%R_o is determined to be between ～1100 m and 1800 m depending on the geothermal gradient. The kerogen composition of the oil shales and the high geothermal gradients result in narrow oil windows, possibly spanning only ～300 to 400 m in the warmest basins. The effective oil window of the coals is estimated to start from ～0.82 to 0.98%R_o and burial depths of ～1300 to 1400 m (～92°C/km) and ～2100 to 2300 m (～62°C/km) are necessary for efficient oil expulsion to occur.     

泥页岩井壁稳定研究及在临盘地区的应用

从岩石力学和物理化学两个主要因素简要分析了井壁失稳的机理，指出泥页岩井壁失稳是由力学与化学两方面因素共同作用的结果。钻井液与泥页岩存在化学势差，并改变了井壁附近的孔隙压力，降低岩石强度。借助于井壁处有效应力的变化,将泥页岩与钻井液相互作用时页岩水化所产生的力学效应与纯力学效应结合起来，计算出任意井斜方位井眼围岩应力状态，利用测井资料求出有关岩石力学参数和Mohr Couloumb准则，计算得出防塌的临界钻井液密度。     

膏盐岩地层地质特征与录井技术

石油勘探实践和研究结果表明，许多油气藏的形成都与膏盐岩地层有关，也常与膏盐岩地层伴生，成功钻穿膏盐岩地层是钻井难题之一，录井技术成为钻进安全监测、膏盐岩地层准确预报的重要手段。针对上述情况，介绍了膏盐岩地层的主要类型、沉积模式以及与油气的关系，归纳总结了膏盐岩地层的录井技术经验，包括：在随钻录井过程中熟悉地质设计与邻井资料；在没有预测钻遇膏盐岩地层的情况下，通过钻井液中Cl^-的变化判定是否钻遇膏盐岩地层；预计钻遇膏盐岩地层时，使用饱和盐水钻井液；钻遇膏盐岩地层后观察盐岩是否以岩屑形式返出；同时，把握膏盐岩地层的岩性、岩性组合、层位、顶底界和厚度是非常重要的。通过S1井实例分析，论述了在膏盐岩地层中钻进时，防卡、防漏是录井人员监测和预报的重点。     

钻井液振动筛叠层筛网透筛率的研究

从理论上详细论述了钻井液振动筛叠层筛网对固相颗粒分离的影响 ,首次提出用透筛率的概念定量地描述这一影响 ,并进行了实例计算。研究表明 ,当上下层筛网随机叠加时对透筛率的影响有以下几种情况 :(1)当上下层筛网开孔尺寸相除的余数为零 ,任意组合叠层筛网的透筛率分别为某一常数 ;(2 )上层筛网目数一定时 ,下层筛网目数越大 ,则透筛率越小 ;(3)上下层筛网的目数相差越小 ,透筛率越小 ;(4 )任意目数的上下层筛网随机叠加后 ,其透筛率仅在一个小范围内变化 ,因此任一叠层筛网有其固有的透筛率属性。     

预测井眼稳定性的力学化学耦合方法

在井眼力学稳定性评价的基础上，将硬脆性页岩水化后岩石强度等参数的变化规律用于页岩水化前后坍塌压力变化的对比分析，结果表明，地层坍塌压力当量密度随页岩水化程度的增加逐渐升高。给出了预测井眼稳定性的力学化学耦合方法，并将该方法应用于现场生产中，取得了较好的预测效果     

Pressurized fluidized-bed hydro retort ing of raw and beneficiated Eastern oil shales

Bench-scale tests were conducted with raw and beneficiated shales in an advanced multi-purpose research reactor. Raw Alabama shale and raw and beneficiated Indiana shales were retorted at 515 °C using hydrogen pressures of 4 and 7 MPa. Shale feed rates were 15 to 34 kg h⁻¹. High oil yields and carbon conversions were achieved in all tests. Oil yield from Alabama shale hydroretorted at 7 MPa was 200% of Fischer assay. Raw and beneficiated Indiana shales hydroretorted at 7 MPa produced oil yields of 170 and 195% of Fischer assay respectively. Total carbon conversions were >70% for all tests conducted at 7 MPa.     

长垣东部深井井壁失稳及技术对策

大庆油田在长垣东部深层油气田勘探开发过程中存在井眼不稳定问题。在对深层失稳井段资料调研的基础上，开展了易塌地层泥页岩水化膨胀及分散特性评价以及比亲水量研究。通过泥页岩--试液模拟作用的化学位差反渗透实验以及压力传递实验等，探讨了不同条件下泥页岩水化应力变化规律。利用井壁稳定性模拟实验装置（SHM仪），评价了不同钻井液防塌效果。理论分析和实验表明，当使用水基钻井液在复杂泥页岩地层钻进时，如何控制泥页岩压力传递和流体侵入是解决泥页岩井壁不稳的技术关键。使用长垣东部深层泥页岩与硅酸盐钻井液作用的实验表明，硅酸盐钻井液能显著降低泥岩渗透率，阻止钻井液滤液与孔隙压力的传递，改善膜效率，有助于充分发挥化学位差诱导的反渗透防塌作用效果。     

提高页岩干馏装置采油率的建议

分析了影响采油效率的三大因素，提出了改进建议。采用新的回收工艺对系统内含油瓦斯进行回收，以提高采油效益。     

轻骨料混凝土抗碳化性能及微结构分析

为了探究轻骨料混凝土抗碳化性能及微结构,采用绝对体积法配制全轻骨料混凝土(ALWAC)和次轻骨料混凝土(SLWAC),并与普通混凝土(NC)比对,测试混凝土在各龄期下的碳化深度,通过MIP压汞测试对比研究NC和ALWAC碳化前后微细观孔结构变化。结果表明:轻骨料混凝土特有的内养护效果,轻骨料周围水泥石日趋密实,因而ALWAC和SLWAC较NC抗碳化性能优,且随碳化时间增长碳化速率显著降低;微结构分析表明经历28 d快速碳化试验后,NC和ALWAC孔隙率分别由14.36%、30.33%下降至13.53%、28.70%,定量说明了碳元素入侵造成大量孔隙被填充细化,与水泥水化产物反应生成CaCO₃,孔径减小,密实度增加。最后给出了基于陶粒掺量的轻骨料混凝土碳化深度预测模型。研究成果可为轻骨料混凝土耐久性预测提供参考。