电成像测井孔隙度分析技术及其在碳酸盐岩储层产能预测中的应用

深入研究了电成像测井的测量方式,提出一种基于电成像低频分量的电阻率刻度公式,结合Archie公式并引入常规测井数据及处理成果,严格推导出一种可将电成像测井数据直接标定为孔隙度的算法。此方法省略了先作电阻率刻度再应用Archie公式等中间步骤,处理过程得以简化,并可消除Archie公式中a、b、n、S_xo、R_mf等参数以及浅侧向测井R_LLS等因素对处理结果的影响,较大程度地实现了数据的自适应性处理。在此基础上,对孔隙度频谱进行多种统计分析,开展了类似核磁的区间孔隙度分析以及类似油藏描述中渗透率评价的孔隙度径向非均质性分析,将研究成果应用于碳酸盐岩储层产能预测中,引入“孔隙贡献因子”概念,并通过测井资料和试油资料建立了“孔隙度贡献因子”与储层产油强度的定量关系。     

Utilizing computational neural networks for evaluating the permeability of compacted clay liners

The design of lined waste-storage facilities is significantly influenced by the permeability of the liner. The permeability of compacted clay liners, in turn, is influenced by factors such as clay type and composition, compaction type and effort, and operating conditions. The complexity of the permeation process makes it difficult to predict analytically the permeability from these factors. As a result, empirical regression models are frequently used to predict permeability. In this paper, permeability prediction models are developed using computational neural networks (CNNS). The developed CNN models are used to predict the permeability of compacted clay for a known set of soil properties and field and laboratory conditions. Moreover, the models are used to determine the relative importance of the various input parameters to the model output. Also, a comparison between regression models and neural networks for predicting permeability is presented and the advantages of utilizing CNN methodology over regression techniques in model development are highlighted.     

BP和RBF在断层防水煤柱留设宽度预测中的应用

在总结全国各典型煤矿断层防水煤柱相关资料的基础上,以水头压力、煤层厚度、安全系数、煤的抗张强度为主要影响因子,选择有代表性的样本数据,通过Matlab软件构建了BP和RBF神经网络模型,对各煤矿断层防水煤柱的留设宽度进行了预测,并与规程经验公式计算的结果进行了对比。结果显示,在煤矿断层防水煤柱留设宽度预测中,RBF神经网络比BP神经网络的训练速度更快,效率更高,具有更加广阔的应用前景。     

超临界CO2温变对低渗透煤层孔渗变化的实验研究

为解决我国高瓦斯煤层渗透性差导致瓦斯抽采率低的难题,利用超临界二氧化碳强扩散和溶解增透等独特优点,采用自制三轴渗透实验装置,开展不同温度下超临界二氧化碳作用后煤的宏观增透实验,在宏观增透实验基础上进行煤微观扫描成像实验。结果表明：恒定体积应力和孔隙压力条件下,不同温度超临界二氧化碳作用后,煤的渗透率较增透前提高一个数量级,但在二氧化碳的超临界温度范围内,煤的渗透率随温度增加呈负指数变化规律。超临界二氧化碳作用后,煤微观孔隙率较增透前提高两个数量级,随着温度增加,煤微观孔裂隙的演化速率减慢,孔隙率随温度增加呈负指数变化规律。宏微观实验数据同时表明,煤宏观渗透率随微观孔隙率增加而增大。超临界二氧化碳增透过程中,孔隙压力对低渗透煤层的增透效果起主控作用。     

覆压作用下页岩的孔渗性实验及其应力敏感性研究

为了研究页岩在应力作用下的孔渗变化及孔隙结构特征,采用四川盆地昭通区块页岩样,不同压力条件下对页岩的孔隙度和渗透率进行实验分析,建立了页岩样孔隙度、渗透性与净覆压之间的相关关系和模型;采用渗透率损害率和应力敏感系数分析了页岩储层的应力敏感性。研究结果表明,页岩基质孔隙度和渗透率随有效应力的增加呈负指数函数规律降低,渗透率与孔隙结构有关,页岩地层中包括基质孔隙和裂隙共同发育的双重介质体系。当净覆压小于5 MPa时,页岩储层应力敏感系数变化较大,应力敏感性强;当净覆压大于5 MPa时,页岩储层应力敏感系数随有效应力的增加下降速度整体减缓,且存在波动变化,应力敏感性减弱,渗透率损害率随有效应力的增大而缓慢增加。研究发现,不同孔径的孔隙度随应力的增大而减小,反映了页岩中不同孔径对孔隙度的协同效应,对揭示页岩储层的孔径变化,指导深部页岩储层的物性特征具有一定的实际意义。     

韩城地区煤储层孔渗应力敏感性及其差异

以韩城煤层气区块3号、5号和11号煤层为例,进行不同围压条件下的煤心孔渗实验,探讨了该区煤储层物性与应力之间的耦合关系,建立了相应的数学模型。结果表明,煤心孔渗随围压的增加而不断下降,渗透率应力伤害远强于孔隙度应力伤害,但各煤层的应力敏感性各不相同：在实验围压从4.14 MPa（600 psi）增加到12.42 MPa（1 800 psi）条件下,11号煤层孔渗应力敏感性最强,孔隙度应力伤害达76.5%,渗透率应力伤害达93.3%;3号煤层孔渗应力敏感性最弱,孔隙度应力伤害38.5%,渗透率应力伤害77.9%;5号煤层孔渗应力敏感性较强,孔隙度应力伤害约45%,渗透率应力伤害达83.9%。分析认为,裂隙发育状况是造成各煤层间孔渗应力敏感差异的主要原因。从实验数据的拟合情况看,幂函数模式比指数函数模式更能准确地获取测试围压范围内的孔渗内插值。     

鸡西盆地下白垩统含煤层系低孔低渗砂岩的成因探讨

黑龙江鸡西盆地下白垩统城子河组和穆棱组是主要的含煤系地层,岩石类型为长石岩屑砂岩和岩屑长石砂岩,成岩作用主要为压实作用、胶结作用、溶蚀溶解作用及交代作用等,露头砂岩经历了表生成岩作用。压实作用和胶结作用是储层砂岩物性差的重要原因,二者相比,前者对该区孔隙度减少贡献更大。对比露头砂岩与岩芯砂岩,露头砂岩的储层物性更好。     

Order of diagenetic events controls evolution of porosity and permeability in carbonates

The properties of carbonate rocks are often the result of multiple, diagenetic events that involve phases of cementation (porosity occlusion) and dissolution (porosity enhancement). This study tests the hypothesis that the order of these events is a major control on final porosity and permeability. A three-dimensional synthetic model of grainstone is used to quantify trends that show the effect of early cementation, non-fabric selective dissolution, and then a second-generation of (post-dissolution) cement. Models are 3 mm³ with a resolution of 10 μm. Six simple paragenetic sequences are modelled from an identical starting sediment (without accounting for compaction) where the same diagenetic events are placed in different sequences, allowing for quantification of relative changes in the resultant porosity and permeability for each diagenetic event, the trajectory through time, as well as for each final rock. All modelled paragenetic sequences result in reductions in porosity and permeability, but the order of diagenetic events controls the trajectory and final rock properties. Differences in the order of early cement precipitation alone produce variable final values, but all follow the porosity–permeability relationship as expressed by the Kozeny-Carman equation. However, final values for the sequences which include a phase of dissolution fall on a new curve, which departs from that predicted by the Kozeny-Carman relationship. This allows an alternative form of porosity–permeability relationship to be proposed: κ = 2280ϕ–30,400, where ϕ is porosity (%) and κ is permeability (mD). Hence while the Kozeny-Carman relationship predicts porosity–permeability changes that occur with cementation, it is unable to capture accurately changes within the pore network as a result of dissolution. Although the results may be dependent on the properties of the initial carbonate sediment and simplified diagenetic scenarios, it is suggested that this new porosity–permeability relationship may capture some generalized behaviour, which can be tested by modelling further sediment types and diagenetic scenarios.     

砂岩储层射孔压实带孔隙度与渗透率损伤研究

射孔孔眼是储层油气进入生产井筒的通道,聚能射孔过程会在孔眼周围砂岩储层产生不同程度的损伤。基于射孔效能物理试验和数值模拟,提出了一种用于定量评价射孔压实带孔隙度和渗透率损伤程度的方法。应用塑性随动强化材料模型表征高应变率冲击载荷下的砂岩形变特性,通过显式动力分析程序LS-DYNA数值模拟孔眼压实区域的砂岩动力学响应,获得了砂岩骨架应力、塑性应变、体积应变等关键数据,结合射孔压实带孔隙度与渗透率演化模型,量化分析了砂岩射孔压实带损伤程度。以胜利油田粒间孔隙砂岩靶为例,数值结果与靶心流动效能测试、CT扫描数据能够较好地吻合,验证了定量评价方法的有效性。结果表明,聚能射孔对压实区域砂岩的损伤主要表现为塑性挤压和剪胀两种机制。在孔道内壁区域,砂岩骨架主要受剪胀作用,孔隙度增加;但塑性挤压又改变了原始孔隙结构,造成流动通道阻塞,渗透率降低。     

长岭断陷火山岩覆压孔隙度和渗透率实验及校正方法

应用覆压条件孔隙度渗透率自动测量仪(AP608)测量的孔隙度和渗透率是在有效覆压下的三轴孔隙度,而储量计算是要求计算油气藏孔隙中的含油气量,应该使用地层条件下的单轴孔隙度.为解决这一问题,笔者通过对长岭断陷安山岩、角砾凝灰岩和凝灰岩的代表性样品进行多个围压下孔隙度的测量,给出了将三轴孔隙度转换为单轴孔隙度的校正方法,转...     

人工神经网络在爆破块度预测中的应用研究

利用人工神经网络模型对爆破块度进行预测,实验结果表明,该方法是完全可行的。通过对实验样本数据进行归一化处理后再对人工神经网络模型进行训练和预测,其预测精度会得到大大提高。