Brittleness index and seismic rock physics model for anisotropic tight-oil sandstone reservoirs

Brittleness analysis becomes important when looking for sweet spots in tightoil sandstone reservoirs. Hence, appropriate indices are required as accurate brittleness evaluation criteria. We construct a seismic rock physics model for tight-oil sandstone reservoirs with vertical fractures. Because of the complexities in lithology and pore structure and the anisotropic characteristics of tight-oil sandstone reservoirs, the proposed model is based on the solid components, pore connectivity, pore type, and fractures to better describe the sandstone reservoir microstructure. Using the model, we analyze the brittleness sensitivity of the elastic parameters in an anisotropic medium and establish a new brittleness index. We show the applicability of the proposed brittleness index for tight-oil sandstone reservoirs by considering the brittleness sensitivity, the rock physics response characteristics, and cross-plots. Compared with conventional brittleness indexes, the new brittleness index has high brittleness sensitivity and it is the highest in oil-bearing brittle zones with relatively high porosity. The results also suggest that the new brittleness index is much more sensitive to elastic properties variations, and thus can presumably better predict the brittleness characteristics of sweet spots in tight-oil sandstone reservoirs.

Influence of brittleness and confining stress on rock cuttability based on rock indentation tests

In order to understand the influence of brittleness and confining stress on rock cuttability,the indentation tests were carried out by a conical pick on the four types of rocks.Then,the experimental results were utilized to take regression analysis.The eight sets of normalized regression models were established for reflecting the relationships of peak indentation force(PIF)and specific energy(SE)with brittleness index and uniaxial confining stress.The regression analyses present that these regression models have good prediction performance.The regressive results indicate that brittleness indices and uniaxial confining stress conditions have non-linear effects on the rock cuttability that is determined by PIF and SE.Finally,the multilayer perceptual neural network was used to measure the importance weights of brittleness index and uniaxial confining stress upon the influence for rock cuttability.The results indicate that the uniaxial confining stress is more significant than brittleness index for influencing the rock cuttability.

Brittleness index predictions from Lower Barnett Shale well-log data applying an optimized data matching algorithm at various sampling densities

The capability of accurately predicting mineralogical brittleness index (BI) from basic suites of well logs is desirable as it provides a useful indicator of the fracability of tight formations.Measuring mineralogical components in rocks is expensive and time consuming.However,the basic well log curves are not well correlated with BI so correlation-based,machine-learning methods are not able to derive highly accurate BI predictions using such data.A correlation-free,optimized data-matching algorithm is configured to predict BI on a supervised basis from well log and core data available from two published wells in the Lower Barnett Shale Formation (Texas).This transparent open box (TOB) algorithm matches data records by calculating the sum of squared errors between their variables and selecting the best matches as those with the minimum squared errors.It then applies optimizers to adjust weights applied to individual variable errors to minimize the root mean square error (RMSE)between calculated and predicted (BI).The prediction accuracy achieved by TOB using just five well logs (Gr,ρb,Ns,Rs,Dt) to predict BI is dependent on the density of data records sampled.At a sampling density of about one sample per 0.5 ft BI is predicted with RMSE~0.056 and R^(2)~0.790.At a sampling density of about one sample per0.1 ft BI is predicted with RMSE~0.008 and R^(2)~0.995.Adding a stratigraphic height index as an additional (sixth)input variable method improves BI prediction accuracy to RMSE~0.003 and R^(2)~0.999 for the two wells with only 1 record in 10,000 yielding a BI prediction error of>±0.1.The model has the potential to be applied in an unsupervised basis to predict BI from basic well log data in surrounding wells lacking mineralogical measurements but with similar lithofacies and burial histories.The method could also be extended to predict elastic rock properties in and seismic attributes from wells and seismic data to improve the precision of brittleness index and fracability mapping spatially.

基于多级特征提取的BiLSTM短期光伏出力预测

传统光伏预测模型易受气象数据波动的影响,且对气象特征不敏感。由此,提出基于多级特征提取的BiLSTM短期光伏出力预测方法,用于预测不同天气类型下的光伏出力。首先,选取与光伏出力相关性较高的气象因素作为输入特征;使用模糊C均值(FCM)聚类方法,对样本进行灵活划分,通过计算Xie-Beni指标以确定最佳聚类数,将历史数据集聚类为晴天、少云天、晴转多云、阴雨天和恶劣天气;其次,构建CNN-CBAM-TCN多级特征提取器(MFE):利用卷积神经网络(CNN)进行初步的特征提取,结合卷积注意力块(CBAM)抑制非重要特征,之后,利用时间卷积网络(TCN)进一步捕捉日内光伏出力的时序特征;最后,借助双向长短期记忆网络(BiLSTM)进行光伏出力预测。在实例分析中,验证了使用Xie-Beni指标确定最佳聚类数的有效性,证明了该模型较其他预测模型在复杂天气类型下具有更高预测精度。

基于PSO-BiLSTM的储层岩石脆性指数预测

脆性指数被认为是一个重要的岩石参数,诸多学者提出了脆性指数的不同计算方法,但是测量方法较为复杂或者成本较高.为了解决上述问题,采用深度学习的方法预测脆性指数,其可以有效融合多元数据,充分利用数据去挖掘自变量与因变量之间的关系.因此,基于常规测井曲线资料,建立了基于粒子群算法(PSO)优化的双向长短期记忆(BiLSTM)模型.实验结果表明,PSO-BiLSTM的MAE=0.0501,RMSE=0.0548,该模型比其他传统方法更精确,更具有实用性和适用性.

基于CNN-BiLSTM-AM的储层岩石脆性指数预测

脆性指数是储层岩石的重要地质力学性质之一,但对于脆性指数至今为止都没有一个明确的定义,许多学者提出了不同的方法来测量该参数,一些方法如矿物分析等成本较高,然而机器学习和深度学习可以有效融合多元数据,充分利用数据去挖掘自变量与因变量之间的关系,且成本较低。因此,该文使用深度学习方法来构建测井曲线数据与储层岩石脆性之间的关系模型。因测井曲线是特殊的时序曲线,该文采用可以综合考虑过去和未来信息的BiLSTM(双向长短期记忆)模型,同时为了进一步的优化,在模型中添加1DCNN(一维卷积)用来提取特征,且引入了AM(注意力机制)。同时利用Pearson系数和XGBoost(极限梯度提升树)进行分析,研究了各测井曲线对脆性的敏感性等级以及重要性程度,最终选取的输入参数有AC(声波时差)、DEN(密度)、CAL(井径)、GR(伽马射线)和SP(自然电位)。与其它机器学习方法相比,该方法的MSE和RMSE最小,分别为0.0035和0.05916,表明CNN-BiLSTM-AM是一种预测精度更高、效果更好的方法。

Effect of hyperbaric oxygen therapy on BI index, GCS, SAS and SDS in patients with craniocerebral injury

Objective: To research and analyze the effect of psychological nursing intervention on self-rating depression (SDS), self-rating anxiety scale (SAS), Glasgow Score (GCS), Barthel index (Barthel, index, BI) of patients. Methods: From September 2015 to September 2016, 84 patients with craniocerebral injury admitted to our hospital were divided into observation group (n = 42) and control group (n = 42) according to randomized single blindness method. All patients were treated with hyperbaric oxygen therapy. The control group was given routine nursing care, while the observation group was treated by psychological nursing intervention. Results: The scores of GCS in the observation group after 2 weeks and 8 weeks of treatment were respectively (7.79±1.42), (11.86±2.56) which were higher than those in the control group (6.23±1.01), (8.21±1.65) the data show significant difference. After treatment, the scores of SDS and SAS in the observation group were respectively (39.14±1.21), (41.67±1.12) which were lower than those in the control group (45.56±2.50), (56.89±2.47) the data show significant difference. The BI index of the observation group was (43.29±4.63), which was higher than that of the control group (36.83±3.10), the scores of NFD was (23.12±1.01) in the observation group, which was lower than that in the control group (28.45±1.67), the data were statistically significant. Conclusion: Psychological care intervention in patients with craniocerebral injury treated by hyperbaric oxygen therapy is helpful to improve the adverse psychological state and consciousness state, improve the ability of daily living activities and promote the recovery of neurological function. It can be actively promoted and applied in clinical practice.

Study on brittleness templates for shale gas reservoirs——A case study of Longmaxi shale in Sichuan Basin,southern China

Differentiating brittle zones from ductile zones in low permeability shale formations is imperative for efficient hydraulic fracturing stimulation.The brittleness index(BI) is used to describe the rock resistance to hydraulic fracture initiation and propagation and measures the ease at which complex fracture networks can be created.In this study,we constructed brittleness templates through the correlation of fundamental rock properties and geomechanical characterization.We then employed the templates to distinguish the brittle,ductile,and brittle-ductile transition zones in the Longmaxi shale gas reservoir,Sichuan Basin of southern China.The approach works in two steps.First,we suggest a new expression for the mineralogical BI by their respective weights based on the analysis of correlation coefficients between mechanical testing and XRD results.Second,we correlate TOC,porosity,pore fluid,natural fractures,and improved BI model with multiple elastic properties to define the brittle,ductile,and transitional zones in the Longmaxi shale gas reservoir of China.Compared with the traditional mineralogy-based BI definition,the improved BI model differentiates the brittle and ductile zones and provides a better sense of the most suitable fracturing regions.Our results show that the brittleness templates,which combine fundamental rock properties,improved BI model,and geomechanical characterization led to identifying favorable zones for hydraulic fracturing and enhanced shale characterization.The proposed brittleness templates’ effectiveness was verified using data from horizontal wells,offset wells,shale gas wells from different origins,laboratory core testing,and seismic inversion of BI across the studied wells.

大型危岩体崩塌灾害早期监测预警技术研究综述

作为中国常见的一种地质灾害,大型危岩崩塌成因复杂、分布范围广、隐蔽性和突发性强、危害性大,其早期预警一直难以实现。通过总结岩体崩塌灾害失稳机理与预警模型可知,开展岩桥结构面损伤识别及静力学-动力学-环境量参量(SDEI)的综合性监测技术研究是实现大型危岩体崩塌灾害早期监测预警的关键所在,而基于分离破坏前兆识别的早期预警机制研究是提高崩塌灾害预警时效性的有效手段之一。随着微机电系统与云边融合技术的发展,在未来有望形成一套稳定性动态评价、失稳工况预测与失稳时间预测模型实时联动的多元预警新范式。与此同时,还需通过不断丰富大型危岩崩塌等脆性破坏灾害预警技术体系,实现危岩体预警等级、稳定性状态、失稳工况、失稳时间的实时分析,进而有效解决大型危岩体崩塌灾害科学精准防控与智慧化应急决策的双重难题。最后,针对目前崩塌灾害早期监测预警研究中存在的技术瓶颈问题,提出具体的发展策略与应对措施,以期为中国地质灾害高风险区更好地应对大型危岩体崩塌灾害提供一些参考。

永进油田致密储集层岩石力学参数剖面构建及应用

为评价低渗致密储集层可压裂性,对准噶尔盆地沙湾凹陷永进油田Y301井和Y3井的6块岩心进行实验,获得岩心矿物组分、孔隙度、应力—应变曲线、纵波速度、横波速度等参数,实验结果与测井、录井数据基本吻合,构建了研究区岩石力学参数经验模型。同时,基于等效介质模型,考虑矿物组分和孔隙结构特征建立了一种新的岩石脆性指数计算模型。在此基础上,提出了基于测井数据的低渗致密储集层力学参数剖面构建方法,并以Y301井为例进行了计算,结果表明,Y301井齐古组可压裂性良好,为致密砂岩储集层可压裂性综合评价奠定了基础。

致密砂岩储层可压裂性测井评价方法

储层的可压裂性是射孔选段和预测水力压裂效果的重要因素,但目前致密砂岩储层的可压裂性评价缺乏统一的方法和标准。以鄂尔多斯盆地东南部某油田长6油层组致密砂岩储层为例,基于常规测井资料优选岩石力学参数的表征模型,通过分析储层岩石脆性、断裂韧性和地应力差异系数与日产液量的关系,建立了致密砂岩储层的可压裂性评价模型及评价标准,获得了与测井曲线对应的压裂品质因子曲线,形成了一种精度较高的致密砂岩储层可压裂性测井评价方法。研究结果表明:①脆性指数与可压裂性呈正相关,断裂韧性和地应力差异系数与可压裂性呈负相关。②当压裂品质因子≥25时,为Ⅰ类储层,可压裂性最好,压裂时容易形成复杂的裂缝网络,属于优质的致密砂岩储层;当14≤压裂品质因子<25时,为Ⅱ类储层,可压裂性中等,压裂时需要采用黏度较小的压裂液或控制较高的缝内净压力,才能形成较好的裂缝网络;当压裂品质因子<14时,为Ⅲ类储层,可压裂性差,压裂时通常不会形成理想的裂缝网络,且压裂后裂缝容易闭合。③致密砂岩储层的压裂品质因子越高,其压裂后的人工裂缝展布形态特征越好,压后产能越高,新建模型的评价结果与微地震裂缝监测结果及试油成果的符合率在80%以上。

准噶尔盆地东南缘页岩油储层脆性预测与评价

准噶尔盆地东南缘二叠系中下部发育页岩油致密储层,脆性预测与评价对其勘探和开发有重要意义。本文利用岩石物理实验、测井资料和叠前地震资料计算了准噶尔盆地东南缘二叠系页岩油致密储层脆性指数,对Rickman经典公式法、杨氏模量与泊松比比值法、拉梅系数法和剪切模量法进行了比较、分析与评价。研究认为:1)杨氏模量相对泊松比对岩性有更好的区分度,由拉梅系数表征的泥岩分布率较高;2)根据文献所得测井多参数计算脆性指数的方法应用效果不佳,在Castagna经验公式换算横波速度基础上计算的脆性指数具有较好的应用效果;3)由YPD(Young's modulus-Poisson's ratio-density)式和LMR(拉梅系数-密度)式反演的弹性参数变化率也能较好地指示有利储层,尤以密度变化率为最佳,该属性在扇三角洲前缘及分流河道特征上得到很好的展示;4)岩石物理实验和实际资料应用均表明,ρE/σ为研究区脆性的最佳表征公式,效果好于Rickman经典公式与其他方法。

盐池地区延长组长8段致密油储层脆性指数测井评价

致密砂岩油气通常需要通过压裂等技术措施方可获得工业产量,而脆性指数是评价储层可压裂性的重要参数,对致密油储层勘探开发甜点优选至关重要。以鄂尔多斯盆地盐池地区三叠系延长组长8段为例,针对致密砂岩储层脆性指数测井评价方法开展系统研究。首先,利用阵列声波测井、岩石声波特性室内实验测试资料,通过求取杨氏模量、泊松比等岩石弹性力学参数,定量计算长8段脆性指数;随后,将利用阵列声波测井资料计算的脆性指数作为目标值,寻找其与自然伽马、横波时差等常规测井资料之间的对应关系;在此基础上,建立基于岩石脆性指数测井预测模型;最后,通过多元回归,全面提取常规测井信息,建立基于常规测井资料的脆性指数多元函数评价模型。根据研究区内单井实例,测井预测脆性指数与岩石声波特性实验测试结果匹配良好,对于脆性指数定量预测,基于岩性指数模型的拟合优度为0.733,基于物性指数模型的拟合优度为0.719,基于多元回归模型的拟合优度为0.789。通过实例验证,脆性指数预测值与实测值变化趋势一致,相关性明显,相关系数达0.936。

基于布谷鸟—BP神经网络的页岩脆性指数预测研究

页岩储层具有低孔隙度、低渗透率的物理性质,因此在页岩气开采中往往需要对其储层进行压裂处理,而页岩储层的可压裂性可用脆性指数来评价。目前应用最广泛的岩石脆性指数计算方法是基于矿物组分法。基于矿物组分法计算获得岩心页岩脆性指数(BI),利用BP神经网络的自我学习能力,探寻测井参数与页岩脆性指数(BI)之间的非线性关系,再结合布谷鸟(CS)算法的全局优化能力和稳定性来提升BP神经网络的预测精度和稳定性,从而建立基于CS—BP神经网络的页岩脆性指数预测模型。使用CS—BP预测模型对研究区Y1井和Y2井两口井进行了页岩BI值预测,其预测结果显示:CS—BP预测值与岩心BI值的变化趋势基本一致;CS—BP预测值总体预测效果较好。研究结果表明:基于布谷鸟(CS)—BP神经网络,利用测井资料快速计算页岩脆性指数的方法在研究区具有一定的实用价值。

右美托咪定对冠状动脉旁路移植术患者麻醉诱导期BIS和血流动力学的影响

目的观察新型α2肾上腺素受体激动剂右美托咪定对冠状动脉旁路移植术（coronary artery bypass grafting,CABG）麻醉诱导期患者脑电双频谱指数（bispectral index,BIS）及血流动力学的影响。方法 2010年6月11日~7月30日30例择期CABG（年龄50~70岁,ASAⅠ~Ⅱ级,心功能Ⅱ~Ⅲ级）随机双盲分为2组：Dex组（n=15）,右美托咪定1μg.kg-1,稀释30 ml静脉泵注（15 min）,继以0.5μg.kg-1.h-1维持输注;对照组（n=15）,生理盐水30 ml,方法同Dex组。监测BIS值,收缩压（systolic blood pressure,SBP）、舒张压（diastolic blood pressure,DBP）、平均动脉压（mean arterial pressure,MAP）、心率（heart rate,HR）,以给药前（T0）、给药后3 min（T1）、6 min（T2）、9 min（T3）、12 min（T4）、15 min（T5）、插管前（T6）、插管结束后1 min（T7）、插管结束后3 min（T8）作为观察记录点。结果麻醉前2组BIS值分别为94.8±2.8和96.3±2.9,无统计学差异（t=-1.441,P=0.161）;与给药前比较,Dex组给药后BIS值逐渐下降,9 min后（T3）下降至84.8±9.7（P=0.034）,15 min后（T5）下降至71.4±13.6（P=0.000）;对照组给药后15 min（T5）BIS值为90.9±4.1,与给药前比较无明显变化,但显著高于Dex组（t=-5.317,P=0.000）。Dex组给药后15 min后（T5）HR明显减慢,由给药前（T0）（64.7±16.4）次/min减至（57.0±11.9）次/min（P=0.024）,但与对照组无明显差异（P〉0.05）;MAP由（101.2±15.1）mm Hg到（100.8±18.8）mm Hg,无明显变化（P=0.927）。麻醉诱导期间,对照组插管后SBP、DBP、MAP、HR值较插管前均有升高,插管后1 min（T7）上述各指标分别为（136.1±36.6）mm Hg（P=0.130）,（75.3±15.5）mm Hg（P=0.000）,（94.4±20.0）mm Hg（P=0.000）,（66.2±13.7）次/min（P=0.009）,插管后3 min（T8）上述各指标分别为（143.5±30.5）mm Hg（P=0.003）,（71.4±12.1）mm Hg（P=0.002）,（92.4±14.8）mm Hg（P=0.002）,（60.1±13.0）次/min（P=0.387）;但Dex组无明显变化（P〉0.05）。结论右美托咪定以负荷剂量1.0μg.kg-1继以0.5μg.kg-1.h-1维持输注对CABG患者产生明显镇静效应,能使BIS值降低,同时降低心率,能维持麻醉诱导期间的血流动力学稳定,减轻插管反应。

变温条件下胶粉改性沥青混凝土抗裂特性研究

为探究胶粉改性沥青混凝土在水利工程环境下的抗裂性能,本文基于小梁弯曲试验及全应力-应变曲线脆性指标,探究了变温条件下胶粉改性沥青混凝土的抗裂性能。结果表明:胶粉改性沥青抗裂性能最优时的配比为80M,掺量20%;低温条件下,胶粉改性沥青混凝土的抗弯强度及峰值应变优于基质沥青混凝土;温度越低,沥青混凝土的脆性指标越大,试件越容易开裂;胶粉的加入降低了基质沥青混凝土的脆性指标,使其抗裂性能有所提升,同时改变了基质沥青混凝土在-10℃时的受力状态,其应力-应变曲线由脆性特征转变为塑性特征。本文研究有望为面板选材提供新思路。

基于基追踪-BI_Zoeppritz方程广义线性脆性指数直接反演方法

非常规油气资源的勘探开发在能源领域越来越受到重视.针对页岩油气、致密砂岩气储层的脆性指数预测,对突破"甜点区"、指导后续水力压裂等都具有重要的意义.针对常规叠前AVO反演技术预测脆性指数存在的问题:(1)稀疏脉冲反演垂向分辨率不高;(2)基于AVO近似公式的常规叠前反演,需要假设常背景纵横波速度比以及弱弹性参数反射率等条件,会影响到三参数反演的精度;(3)通常需要借助反演获取的纵横密三参数转换为杨氏模量和泊松比,再进一步转换才能获取脆性指数,在参数转换的过程中会将误差累积放大,影响最终的脆性指数预测精度.本文从精确Zoeppritz方程出发,通过对其进行重新推导,将其表达为脆性指数、P波速度和S波速度的函数(BI_Zoeppritz方程),并借助广义线性AVO反演,对基追踪反演获取的高分辨率角度反射系数进行迭代反演,直接提取高分辨率、高精度的脆性指数.通过模型和实际资料验证了该算法相对常规叠前反演获取的脆性指数有了进一步的改善.

页岩层系不同岩矿组合试样渗透率变化规律差异及其机理分析

页岩地层垂向岩矿组合变化大,页岩气开采需要对储层进行大规模人工水力压裂改造。笔者等基于样品的全岩X-射线衍射分析,通过对不同岩矿组合的3块页岩试样进行流—固耦合物理模拟实验,获得了3点认识,反映了不同岩矿成分的页岩在不同条件微裂缝与渗透率的变化特征,以及碳酸盐矿物含量高时的影响。这一实验对于研究页岩储层在压裂过程中的变化具有探索性,对于页岩气生产具有重要的参考意义。

BIS监测预防全凭静脉麻醉下术中知晓的多中心研究

目的 评估BIS监测在丙泊酚全凭静脉麻醉（total intravenous anesthesia,TIVA）下预防术中知晓的作用,探讨术中知晓的可能原因。方法 采用多中心、大样本、前瞻性的随机、双盲、分组对照研究方法,患者（年龄≥16岁）被随机分为BIS监测指导组（A组,监测并维持BIS值40-60）和对照组（B组,监测BIS但遮挡显示屏）。分别于术后第1天和第4天随访,由独立的评估委员会作明确和可疑知晓的判断。术后间隔一定时间导出BIS数据,分析明确知晓病例的BIS趋势以判断是否存在浅麻醉。明确两组知晓的发生率。结果 共收集5 228例有效病例,其中A组2 919例,B组2 309例。明确知晓病例A组4例（0.14%）,B组15例（0.65%）,两组比较差异有统计学意义（P=0.002,OR=0.21,95%置信区间：0.07-0.63）。两组可疑知晓（A组0.14%,B组0.26%,P=0.485）和做梦（A组3.1%,B组3.1%,P=0.986）的发生率差异无统计学意义。19例明确知晓病例的术中BIS趋势和麻醉总结显示,8例（A组3例,B组5例）无BIS及知晓原因分析;6例获取了相应的BIS趋势图,其中5例（A组1例,B组4例）BIS趋势提示有明确浅麻醉表现,1例（B组）BIS基本稳定于60及以下;其余5例（B组）知晓经主管麻醉医生回顾,有术中浅麻醉和BIS波动且升高〉60的情况。结论 行BIS监测并维持BIS值40-60可有效减少TIVA术中知晓的发生。发生知晓的主要原因为术中浅麻醉。

高压氧疗法对颅脑损伤患者BI指数、GCS、SAS、SDS的影响

目的:分析心理护理干预对颅脑损伤高压氧治疗患者的干预效果及对患者抑郁自评量表(Selfrating Depression Scale,SDS)、焦虑自评量表(Self-Rating Anxiety Scale,SAS)、格拉斯哥评分(GCS)、Barthel指数(Barthel,index,BI)的影响。方法:收集2015年9月~2016年9月我院收治的颅脑损伤患者84例,按照随机单盲法分为观察组(n=42)和对照组(n=42),均给予高压氧治疗,对照组给予常规护理,观察组实施心理护理干预。结果:治疗后2、8周,观察组患者GCS评分[(7.79±1.42)、(11.86±2.56)分],高于对照组[(6.23±1.01)、(8.21±1.65)分](P<0.05);治疗后,观察组患者SAS、SDS评分[(39.14±1.21)、(41.67±1.12)分]低于对照组[(45.56±2.50)、(56.89±2.47)分](P<0.05);观察组BI指数对照组,NFD评分低于对照组,差异具有统计学意义(P<0.05)。结论:对高压氧治疗的颅脑损伤患者,心理护理干预有利于改善不良心理状态和意识状态,提高日常生活活动能力,促进神经功能恢复,可在临床积极推广和应用。