用历届吸水剖面和压降资料确定储层大孔道的方法

油田由于长期注水开发,储层的渗透能力明显增强,个别储层已形成了大孔道.识别、治理大孔道是油田进入高含水开发阶段主要工作之一.利用压降法分别计算注水井各个时期的储层渗透率,分析其变化趋势,结合历届关井初期地层压降速度和幅度可以判断注水井大孔道.当储层有效渗透率明显增大,关井初期前5 min内降落幅度是全井降落幅度50%以上,且压力导数双对数曲线中期出现凹型时,注水井存在大孔道.对于存在大孔道的注水井,同位素曲线和流量曲线皆显示的主要吸水层就是大孔道层位;同位素曲线显示不吸水,而流量曲线和井温曲线皆显示的主要吸水层也是大孔道层位,需要对这些层位采取调剖措施.该方法为油田下一步措施、实现储层精细注水提供了依据.     

甘陕古河中段侏罗系延10油藏初产产能预测技术研究

为了建立甘陕古河中段侏罗系延10油藏初产产能预测模型,服务于油藏开发技术政策的制定,本文基于研究区的地质资料、岩心资料、测井资料和动态生产资料等,开展了四个井区的地层划分与对比、储层特征分析、延101油层初产产能宏观与微观敏感因素分析,在此基础上选择宏观及微观敏感因素,利用多元回归的方法建立了四个井区的初产产量预测模型,实现了多井区初产产量分区预测.研究表明,延101油层为本区主力油层,虽然分布在不同古地貌上背景上的延10油藏地层厚度稳定,但是不同类型古地貌背景上的油藏渗透率差异较大;微构造、有效厚度等宏观因素与四个井区的初产产量关系最好,微观因素中的含油饱和度与四个井区的初产产量相关性好于孔隙度、渗透率;基于不同井区宏观、微观敏感因素建立的初产产量预测模型预测效果好于传统模型.     

油井产液量与井底压力关系的研究

利用流体动力学理论,研究了油井产量与井口压力、井底压力之间的产量关系,给出了井口压力和油井产液量之间的等效互换关系,进一步研究了油井动态观测资料的科学处理方法,以胜利油田东水－３井为例,对其观测资料进行了处理,并讨论了泄流管管径对流量及等效水位的影响。     

长春岭油田储层预测研究

常用的储层横向预测技术有地震属性分析技术和地震反演技术两大类,应用这两种技术对长春岭油田扶余油层进行了储层预测研究.研究结果表明,长春岭油田地震资料的振幅属性与已知井砂岩发育情况吻合较好,本文利用振幅属性描述了扶余油层Ⅰ～Ⅳ砂组储层砂岩的分布趋势.应用地震反演方法得到扶余油层储层砂岩纵横向展布规律,经钻探证明,预测的结果比较可靠.     

考虑动态克林伯格系数的煤储层渗透率预测模型

随着储层压力的降低,克林伯格效应对渗透率的影响越来越大.现有的煤储层渗透率预测模型大都忽略了克林伯格系数的变化,其预测结果与实际生产存在一定的差异,尤其是在低储层压力阶段.本文以体积不变假设为基础,基于火柴棍模型给出在储层压力降低过程中动态克林伯格系数的计算公式,并建立考虑动态克林伯格系数的渗透率预测模型;深入分析在煤储层压力降低过程中,煤储层渗透率和克林伯格系数的变化规律.研究结果表明：随着储层压力的降低,克林伯格系数呈先增大后减小的变化趋势;在相同储层压力下,克林伯格系数随渗透率增加呈指数减小趋势,随温度增加呈线性增大趋势.本文建立的渗透率模型参数简单易获取,预测结果与实际煤储层渗透率变化规律符合性较好,尤其是在低储层压力阶段,能准确预测煤储层渗透率变化.     

基于地质因素约束的水淹层测井评价方法——以中亚地区孔隙型碳酸盐岩油藏M为例

开展水淹层评价是实现M油藏增储上产的重要基础.然而,M油藏研究区套管测井和生产测井资料缺失.以含水率作为水淹特征的指标,综合开发地质特征和生产数据,统计表明:研究区水淹层分布与地层构造、沉积相、物性、重力和开发井网有关.为了实现水淹影响因素与测井评价资料的结合,提出基于地质因素约束的测井水淹层评价方法.方法以注采井组为单元,采用表征注采井间地质特征差异的参数(如地层构造差、产层渗透率差、井距和注见水时间差)和测井解释参数(如饱和度),通过数据统计分析,建立地质因素控制的水驱前缘到达时间、水淹层含水率变化速率的预测模型,实现现今水淹层及剩余油分布预测和解释.预测结果得到实际生产数据和油藏数值模拟结果的检验,显示本文提出的水淹层评价方法具有可行性,为水淹层研究提供了一定借鉴和参考.     

利用梯度提升决策树(GBDT)预测渗透率——以姬塬油田西部长4+5段致密砂岩储层为例

致密砂岩储层的研究对于当前国内油气勘探进展至关重要.准确掌握致密砂岩储层特征是开展油藏描述和有利区优选等工作的重要前提,而获取储层表征参数又是刻画储层特征的关键,所以储层参数预测技术逐渐成为当前研究热点之一.渗透率是划分油气水层以及后续井开发工程的重点分析要素.对于致密砂岩储层而言,因其非均质性强,使得渗透率很难用常规方法准确求取.为此,本文根据机器学习在数据分析上的强大性能,提出利用GBDT技术预测致密砂岩储层渗透率.本文以姬塬油田西部长4+5段致密砂岩储层测井资料为基础,通过设计2个实验来验证提出方法预测效果.为突出提出方法的预测能力,在实验中引入逐步迭代、Timur模型和BP模型进行对比.2个实验结果显示提出方法得到的拟合误差最小,证明GBDT技术能够有效用于致密砂岩储层渗透率预测,并且预测资料仅需测井数据,无需其他实验数据支撑,表明技术具有良好的推广性.     

小断层的地震识别

在勘探后期或油田开发阶段,认清小断层的分布对油田注采井设计、产能建设、油藏管理和油藏挖潜等的落实具有极为重要的意义.受地震资料分辨率的限制,用常规的地震资料解释方法进行小断层的识别很难达到油田生产需求,为此,本文根据研究区储层不同厚度、物性特点,以测井、地震、地质统计为基础,设计了薄层、厚层和不等厚互层三种储层不同断距...     

火山岩储层流动单元识别与刻画——以松辽盆地营城组为例

利用测井资料确定有效储层物性下限并识别隔挡层,结合岩性—岩相等定性分析方法和聚类—判别等定量分析方法综合识别相邻隔挡层间连通火山岩体内的储层流动单元.以岩心和测井资料为基础,用孔隙度、渗透率、声波时差、补偿中子和补偿密度共5个参数进行聚类分析和判别分析,实现由取心井段到全井段储层流动单元的刻画,将XS1井区火山岩储层流...     

利用阵列感应测井进行储层渗透率评价

钻井过程中储层受到泥浆侵入影响的程度与储层岩性有着密切关系,其中储层渗透率对侵入深度有着较大影响,因此若可以获知泥浆侵入深度,则有望对储层渗透率进行评估.本文首先建立含泥饼增长的泥浆侵入数值模型,然后建立阵列感应测井数值模型,两者的联合正演模拟显示泥浆侵入对地层的影响可以反映在阵列感应测井响应上,利用阻尼最小二乘法对阵列感应测井响应进行反演可以得到侵入深度.对侵入深度和储层渗透率的关系进行分析发现:在渗透率为1～100mD(1mD=0.987×10~(-3)μm～2)数量级的储层中,渗透率的变化可以在侵入深度上得到反映.以储层和井数据进行二维数值模拟发现:利用阵列感应测井响应反演出来的侵入深度曲线反映了渗透率在地层上的变化趋势,采用解释图版的方法可以对储层各层段的渗透率进行粗略估算.     

Inversion of dynamic production data for permeability: fast streamline-based computation of sensitivity coefficients of fractional flow rate

Generation of permeability field in a reservoir model that matchs historical dynamic production data requires an inverse calculation. A gradient method is typically used to solve the inverse minimization problem and requires sensitivity coefficients of reservoir responses, e.g. fractional flow rate or pressure, with respect to the change in the permeability. This paper presents a novel semi-analytical streamline-based method for computing such sensitivity coefficients under the framework of two-phase (oil-water) flow conditions. This method is shown to be significantly faster and generate permeability fields with lower objective function than the traditional perturbation method. The method decomposes the multiple-dimensional full flow problem into multiple 1D problems along streamlines. The sensitivity of fractional flow rate at the production well is directly related to the sensitivity of time-of-flight (TOF) along each individual streamline and the sensitivity of pressure at grid cells along the streamline. The sensitivity of TOF of a streamline can be obtained analytically. The sensitivity of pressure is obtained as part of a fast single phase flow simulation. The proposed method is implemented in a geostatistically based inverse technique, called the sequential self-calibration (SSC) method. Results for fractional flow rate sensitivities are presented and compared with the traditional perturbation method. This new method can be easily extended to compute sensitivity coefficients of saturation (concentration) data.     

A time-domain induced-polarization method for estimating permeability in a shaly sand reservoir

It is known that the time‐domain induced‐polarization decay curve for a shaly sand reservoir depends on the pore structure of the reservoir, and this curve can be used to estimate permeability, which is a determining factor in making production decisions in the petroleum industry. Compared with NMR logging tools, induced polarization has several advantages, such as a deep depth of investigation and a high signal‐to‐noise ratio. The purpose of this paper is to establish an appropriate model using induced polarization to estimate the permeability. The curve can be modelled as a weighted superposition of exponential relaxations. The plot of weight versus the relaxation time constant is defined as the relaxation time spectrum. Induced‐polarization decay‐curve measurements were performed on 123 samples from the Daqing oilfield using a four‐electrode technique. A singular‐value decomposition method was used to transform the induced‐polarization decay data into a spectrum. Different models to estimate the permeability were discussed. The results of the research indicate that the induced‐polarization measurements greatly improve the statistical significance of permeability correlations. Compared with the traditional forms, Aφ^C and AF^C, the forms, AT^Bφ^C and AT^BF^C, have lower error factors, where T, Φ and F are the geometric mean time constant of the induced‐polarization relaxation time spectrum, the porosity and the resistivity formation factor, respectively, and A, B and C are constants. The mean time constant is the decisive parameter in the permeability estimation and it is not completely independent of the resistivity formation factor. The additional use of the porosity and the resistivity formation factor leads to an appreciable improvement. It is concluded that this new model will make it possible to estimate the permeability of a shaly sand reservoir downhole.     

Characterization of fractured reservoirs using a consistent stiffness‐permeability model: focus on the effects of fracture aperture

In this paper we propose a method for the characterization of naturally fractured reservoirs by quantitative integration of seismic and production data. The method is based on a consistent theoretical frame work to model both effective hydraulic and elastic properties of fractured porous media and a (non‐linear) Bayesian method of inversion that provides information about uncertainties as well as mean (or maximum likelihood) values. We model a fractured reservoir as a porous medium containing a single set of vertical fractures characterized by an unknown fracture density, azimuthal orientation and aperture. We then look at the problem of fracture parameter estimation as a non‐linear inverse problem and try to estimate the unknown fracture parameters by joint inversion of seismic amplitude versus angle and azimuth data and dynamic production data. Once the fracture parameters have been estimated the corresponding effective stiffness and permeability tensors can be estimated using consistent models. A synthetic example is provided to clearly explain and test the workflow. It shows that seismic and production data complement each other, in the sense that the seismic data resolve a non‐uniqueness in the fracture orientation and the production data help to recover the true fracture aperture and permeability, because production data are more sensitive to the fracture aperture than the seismic data.     

A feasibility study of borehole radar as a permanent downhole sensor

Permanent downhole sensors provide the eyes and ears to the reservoir and enable monitoring the reservoir conditions on a real‐time basis. In particular, the use of sensors and remotely controlled valves in wells and on the surface, in combination with reservoir flow models provide enormous benefits to reservoir management and oil production. We suggest borehole radar measurements as a promising technique capable to monitor the arrival of undesired fluids in the proximity of production wells. We use 1D modelling to investigate the expected signal magnitude and depth of investigation of a borehole radar sensor operating in an oilfield environment. We restrict the radar applicability to environments where the radar investigation depth can fit the reservoir size necessary to be monitored. Potential applications are steam chamber monitoring in steam assisted gravity drainage processes and water front monitoring in thin oil rim environments. A more sophisticated analysis of the limits of a radar system is carried out through 2D finite‐difference time‐domain simulations. The metal components of the wellbore casing can cause destructive interference with the emitted signal. A high dielectric medium surrounding the production well increases the amplitude of the signal and so the radar performance. Other reservoir constraints are given by the complexity of the reservoir and the dynamic of the fluids. Time‐lapse changes in the heterogeneity of the background formation strongly affect the retrieval of the target reflections and gradual fluid saturation changes reduce the amplitudes of the reflections.     

Bayesian inversion of time‐lapse seismic data for the estimation of static reservoir properties and dynamic property changes

Seismic conditioning of static reservoir model properties such as porosity and lithology has traditionally been faced as a solution of an inverse problem. Dynamic reservoir model properties have been constrained by time‐lapse seismic data. Here, we propose a methodology to jointly estimate rock properties (such as porosity) and dynamic property changes (such as pressure and saturation changes) from time‐lapse seismic data. The methodology is based on a full Bayesian approach to seismic inversion and can be divided into two steps. First we estimate the conditional probability of elastic properties and their relative changes; then we estimate the posterior probability of rock properties and dynamic property changes. We apply the proposed methodology to a synthetic reservoir study where we have created a synthetic seismic survey for a real dynamic reservoir model including pre‐production and production scenarios. The final result is a set of point‐wise probability distributions that allow us to predict the most probable reservoir models at each time step and to evaluate the associated uncertainty. Finally we also show an application to real field data from the Norwegian Sea, where we estimate changes in gas saturation and pressure from time‐lapse seismic amplitude differences. The inverted results show the hydrocarbon displacement at the times of two repeated seismic surveys.     

储层裂缝识别与评价方法新进展

裂缝发育程度决定着低渗储层的渗流和产出能力,但由于裂缝发育机制的复杂性,故裂缝性油气藏一直是勘探的重点和难点.目前裂缝评价方法多以常规测井资料为主,结合其它分辨率较高的诸如FMI测井、地层倾角测井等.本文列举的计算机层析成像技术、ANN技术、灰色系统评判法是在裂缝研究领域相对有效的识别和评价方法,在油田的现场应用中取得了良好效果.     

波浪作用下成层海床孔隙水压力响应的简化分析

采用不排水条件下孔隙水压力发展模式,作为Terzagh i一维固结方程中考虑波浪循环作用所引起的孔隙水压力源项,对于成层海床建立了推广的一维动力固结方程,运用数理方程中的分离变量法与G reen函数求解了成层海床在波浪作用下残余孔隙水压力的发展规律,进而对成层海床的液化势进行了评判。对比计算与分析表明,海床表层土的渗透性及其厚度对于海床的整体抗液化性能具有显著的影响,低渗透性的表层导致海床孔隙水压力的显著积累,此时表层置换法是防治液化的有效途径。     

区域特性约束下的油藏物性模拟

为了提高油藏物性模拟的精度,本文提出了包含两个约束条件的目标函数,考虑在既满足井条件与空间结构变化,同时又满足油田范围内观测到的油藏物理性质的约束下,应用模拟退火算法,对孔隙度的空间分布进行预测模拟.由于目标函数有效地结合了静、动态信息,从而降低了模拟结果的不确定性,提高了模型的精度.合成数据的油藏物性模拟试验表明,该方法收敛快、稳定性好,模拟的结果令人满意.     

龙滩水库诱发地震三维孔隙弹性有限元数值模拟

本文以龙滩水库为例,根据库区地质构造、深部速度结构及数字地面高程,建立了库区三维有限元模型,基于孔隙弹性理论计算了水库蓄水过程中库底断层和围岩体孔隙压力、有效附加正应力、剪应力和库伦应力的动态变化,并结合水库蓄水后库区地震活动时空分布的特征,讨论了RIS时空演化与库水加卸载及渗透过程的动态响应关系及其可能的成因机制.结果表明：（1） 龙滩水库蓄水后地震活动呈现出明显的丛集性,主要分布在罗妥（丛Ⅰ）、八茂（丛Ⅱ）、拉浪（丛Ⅲ）、坝首（丛Ⅳ）和布柳河（丛Ⅴ）5个水库蓄水后淹没的深水区,这些区域也恰恰是库水加卸载及渗透过程中ΔCFS增加最明显的区域,而ΔCFS的影区几乎没有地震发生,表明水库蓄水后库区地震活动与ΔCFS的变化密切相关.（2） 在水库蓄水过程中,与水库有直接水力联系且渗透性较好的断裂成为地表水体附加水头压力向深部扩散的优势通道,沿此通道附加水头压力扩散的最大深度达13 km左右,震旦系-古生界以碳酸盐岩为主的地层成为附加水头压力扩散的主体层位,这与蓄水后库区中、小地震震源深度均小于13 km,且优势分布在5~10 km的特征相吻合,表明由于孔隙压力的存在降低了岩石的抗剪强度,同时部分抵消了围压的影响,致使该层位的岩体易于产生脆性破坏从而诱发地震活动.（3） 无论是深部还是浅部,各丛地震密集发生的时段绝大部分与相应深度ΔCFS加速升高或阶段性高值时段相重叠,可能说明在库水位快速抬升或阶段性高值时段,受外部荷载加载速率快速升高的影响,库底岩体和断层、裂隙等结构面更容易实现失稳扩展;深、浅部地震响应时间、活动频度和强度的差异可能与不同层位岩体力学性质及渗透性能的不均匀性有关.（4） 各丛地震诱发的物理力学机制有所不同.丛Ⅰ、丛Ⅱ、丛Ⅲ地震的诱发可能与库体重力荷载、孔隙压力扩散和库水浸润弱化3种作用都有关;丛Ⅳ地震的诱发主要受控于库体重力荷载作用,孔隙压力扩散和库水浸润弱化不起主导作用;丛Ⅴ地震的诱发主要受孔隙压力扩散和库水浸润弱化作用的影响,库体重力荷载作用一定程度上抑制了地震的发生.