A framework to integrate history matching and geostatistical modeling using genetic algorithm and direct search methods

History matching is an inverse problem where the reservoir model is modified in order to reproduce field observed data. Traditional history matching processes are executed separately from the geological and geostatistical modeling stage due to the complexity of each area. Changes made directly on the reservoir properties generally yield inconsistent geological models. This work presents a framework to integrate geostatistical modeling and history matching process, where geostatistical images are treated as matching parameters. The traditional optimization methods normally applied in history matching generally use gradient information. The treatment of geostatistical images as matching parameters is difficult for these methods due to the strong non-linearities in the solution space. Therefore, another objective of this work is to investigate the application of two optimization methods: genetic algorithm and direct search method in the proposed framework. In order to accelerate the optimization process, two additional techniques are used: upscaling and distributed computing. Results are presented showing the viability of the genetic algorithm in the type of problem addressed in this work and also that direct search method can be used with some restriction. Finally, the benefits of distributed computing and the consistence of the upscaling process are shown.     

三层越流油藏井底压力的精确解

采用最大有效井径概念,在考虑表皮效应和井筒储存影响的条件下,建立了无限大边界、定压边界、封闭边界的三层越流油藏井底压力的动态模型。用拉氏变换方法得到了拉氏空间下以Bessel函数表示的井底压力和分层流量精确解。运用Crump数值反演方法得到了实空间的解,分析了压力动态特征。新模型既适合于表皮因数为正的情况,也适合于表皮因数为负的情形。用新模型绘制的典型曲线进行拟合,得到的结果更加准确。     

边水油藏剩余油分布数值模拟研究

H1油藏为一背斜层状低幅度边水油藏,经过15年的开发,油田已经进入高含水阶段,产量递减加快。利用数值模拟技术,通过设置Fetkovich解析水体、修改断层传导率等敏感性参数对H1油藏进行历史拟合;研究了油藏剩余油分布特点,为油田下一步的稳产甚至增产提供有利条件。     

An analytical model for production data analysis of under saturated oil reservoirs subjected to edge aquifer

Analysis of production data is an important method for estimating recoverable reserves and probable life of the reservoirs. Robust techniques for analysis of production data have been developed and widely used for many years. These methods range from the traditional Arps decline method to modern production data analysis. The most recent techniques are based on material balance time to account for variable operating conditions. In these methods, production rate and flowing bottom hole pressure must be known. A major limitation of many existing modern techniques is volumetric assumption of the reservoir.This paper presents a new model that accounts for non-volumetric effects of edge aquifers on production data analysis of single phase oil reservoirs by defining a new material balance time function. This new time function and material balance time help us to introduce flowing material balance (FMB) equations for such reservoirs. Validity of these equations is justified using analytical solutions. For development of analytical solutions, special simplifying assumptions are considered. To justify these assumptions, comparison is made using a commercial numerical reservoir simulator across some ranges of reservoir parameters.Furthermore, based on the validated FMB equations and obtained analytical flow equations, specific procedures are developed for parameter estimation of such reservoirs. The use of these procedures in estimation of oil in place and reservoir external radius is demonstrated using synthetic examples. On the basis of the considered assumptions, the proposed procedures cannot be applied to multi-phase flow conditions, reservoirs with other types of aquifer (such as bottom aquifer), and gas reservoirs.We also show that the given FMB equations are applicable for any irregularly shaped reservoir which is partially contacted with a non-cylindrical limited edge aquifer. For such reservoir geometries, numerical solution is used for justification. This is followed by introducing a simple equation for predicting average reservoir pressure.     

利用抽汲井液面恢复资料解释双孔介质油藏地层参数

非自喷井的抽汲求产是一个很复杂的间歇生产过程。为了不影响抽汲井的产量,利用液面检测仪对抽汲井停产时获取液面恢复数据,并利用相关数据对地层参数进行解释计算,这种技术无疑是今后求取地层参数的主要方向。文中针对双重孔隙介质圆形封闭油藏建立了地层中心一口抽汲井液面恢复的渗流模型,在考虑井筒储集效应和表皮系数的情况下,应用拉普拉斯变换和贝塞尔函数理论对定解问题求解,得到了模型在拉普拉斯空间的精确解,并对曲线图版及拟合过程进行分析。利用曲线图版拟合可以解释原始地层压力,对不关井试井有很好的指导意义,从而也扩大了其应用范围。     

A New Methodology for Assisted History Matching Using Independent Objective Functions

Abstract

History matching is a complex inverse problem for which the degree of difficulty and the computational effort (in terms of number of simulations) increase with the increasing of the number of matching parameters. This article presents a new methodology for assisted history matching based on independent objective functions that decrease the number of simulations. The proposed approach consists of the optimization of several objective functions related to each region of the reservoir to be matched, such as a well or a group of wells. Optimization processes, one for each objective function, are started simultaneously, modifying the same data file, yielding a more efficient process, allowing speedup and preserving the quality of the results. The methodology was successfully applied to an offshore field. The results show that the quality of results is practically the same when compared to the conventional procedures, i.e., matching of the wells individually or combining several wells. The advantage is a significant reduction on the number of simulations, preserving the quality of the results.     

基于多次数据吸收集合平滑算法的自动油藏历史拟合研究

针对常见历史拟合方法存在计算量大、油藏参数更新异常、油藏模型修正失真等问题.采用集合平滑算法,通过引入集合卡尔曼滤波算法(EnKF)中多次迭代思路,对相同数据重复吸收,推导出多次数据吸收集合平滑算法(ES-MDA)的核心公式,并编写了自动油藏历史拟合软件.以北海布伦特油田海相砂岩油藏为例,将基于ES-MDA算法的油藏自...     

利用数值模拟反演聚合物驱物理实验的方法

历史拟合是油藏数值模拟技术的重要组成部分,但历史拟合的过程是一个复杂而艰难的过程,尤其是聚合物驱历史拟合。本文提出了一套数值模拟反演方法,其为在进行历史拟合之前先对聚合物驱物理实验进行数值模拟反演,分析聚合物驱的主要影响因素,对后期的历史拟合过程具有很好的指导意义。用该方法对JZ9—3油田胶结岩心实验反演的结果表明,拟合效果较好,再现了物理实验的过程。     

多层长岩心水驱油实验数值模拟研究

多层长岩心水驱油实验,主要用于解决纵向非均质油藏普遍存在的层间矛盾突出、水驱效率低、低渗储层难以动用等问题而开展的.文中在完成了多层长岩心水驱油实验的基础上对实验结果分别进行了考虑启动压力梯度和不考虑启动压力梯度的拟合,结果表明,考虑启动压力梯度的拟合结果更好.选择其中拟合效果较好的模型给出的网格压力、饱和度数据进行了水驱油渗流场变化研究,研究结果表明:高中低渗层的压力、含油饱和度分布随注入速度的提高分别有所提高和降低,且同时表现出高渗层变化不明显;不同工作制度下低渗层压力变化很大,即提高驱替速度时低渗层的压力在高渗层开时会下降,反之提高驱替速度关闭高渗层会大幅增加低渗层的压力.     

Streamline-Based History Matching Constrained to Reservoir Geostatistics Using Gradual Deformation Technique

Abstract

A new and general procedure for history matching that uses streamline simulation and a gradual deformation technique has been proposed. Streamline trajectories define the major flow paths and help the algorithm to modify the reservoir model only in the regions that cause the mismatch between simulation results and field observations. The use of a gradual deformation technique enables the algorithm to remain constrained to reservoir geostatistics. It also reduces the number of independent variables in the optimization problem. In our algorithm, effective conductivities are defined along each streamline. The effective streamline conductivities are then adjusted using the values of measured and computed breakthrough times of individual streamlines. Then an intermediate objective function is defined to minimize the difference between adjusted (desired) and computed effective streamline conductivities. The algorithm continues until a satisfactory match is obtained. In order to examine the quality of our history matching procedure, it is applied to a synthetic reservoir.     

涩北一号气田开发方案设计

以涩北一号气田精细描述资料为基础，对第3开发单元进行了数值模拟研究，并将储层非均质性从对渗透率非均质表征延伸到了对岩石与流体相互作用关系的表征。在历史拟合的基础上，充分考虑气井单井产能、不积液临界产气量和出砂压差，对不同采气速度下的单井进行配气，3种采气速度下的气田开发指标优化结果表明，涩北一号气田第3开发单元的合理采气速度为3．08％，对比相同采气速度下上返与合采方案的产水动态可以看出，合采方案的生产动态较好，稳产年限为18a。第3开发单元的生产动态历史拟合结果表明，基于气田描述地质模型的模拟计算结果与生产动态相吻合，表明气田地质模型较为可靠。     

Using downhole temperature measurement to assist reservoir characterization and optimization

Without initial seismic or detailed geological information, reservoir characterization is difficult. Downhole temperature distribution in horizontal wells is an important source that helps to characterize the reservoir and understand the bottom-hole flow conditions. The temperature measurements are obtained from permanent monitoring systems such as downhole temperature gauges and fiber optic sensors. Additionally, production history and bottomhole pressures are usually readily available and are routinely used for history matching to improve the initial geological models. By combining the downhole temperature distribution and the production history, more reliable information can be extracted about the reservoir permeability distribution and bottomhole flow conditions in order to optimize the wellbore performance, particularly in horizontal wells.In this paper, a thermal model and a transient, 3D, multiphase flow reservoir model are used to calculate the wellbore temperature distribution in horizontal wells. By comparing the simulated temperature and the observed data, large-scale permeability trends in the reservoir are derived. These permeability trends are then incorporated as ‘secondary’ information in the geologic model building and history matching. The final outcome is a geologic model that has the constraints of both temperature and production history information.A synthetic case is presented to illustrate the procedure. The results show when using production history matching only without distributed temperature data along the wellbore, the water entry location in horizontal wells cannot be detected satisfactorily. By combining production history matching with downhole temperature distribution data in a wellbore, an improved geological model is developed that can match production history and locate water entries correctly. Based on the downhole flow conditions and the updated geological model, the well performance can be optimized by controlling the inflow rate distribution in a horizontal well.     

一种新的自动拟合试井解释法

本文主要讨论改善自动拟合试井解释法——现代试井解释的一种重要方法的收敛性以及多解的问题。这些问题大大地妨碍了这种方法在实际油田中的应用。本文以均质油藏模型为基础,利用系统工程的观点,将压力曲线按其所表征的参数的敏感度不同分为两段。采用分段拟合的方法,用一种新的迭代过程,代替原有的拟合方法。理论分析和实际应用结果表明,这种方法提高了计算结果的收敛性,改善了解的唯一性,原则上这种思路可以推广到双重介质等复杂油藏模型的自动拟合试井解释中。     

热采水平井变质量流与油藏渗流的耦合数值模拟

为真实反映水平井及近井地带的流体流动情况，需要将水平井井筒内的流动与在油藏中的渗流耦合进行油藏数值模拟。假设“微元段”，引用“交错网格”和“等效渗透率”概念，建立了热采水平井井筒变质量流的等效渗流模型；在此基础上提出耦合井筒变质量流与油藏渗流的水平井产量公式，建立了井筒变质量流与油藏渗流耦合的数学模型。利用该模型进行热采水平井开采机理研究，认为：水平井井筒内的压降影响水平井生产动态，忽略压降将使计算的产油量和油汽比偏高；水平井所产油主要来自水平井筒的始端，在一定的油藏条件、水平井参数等情况下，每口水平井都有最优水平段长度。图2表1参5     

低渗透砂岩储集层油藏评价一体化研究方法及应用

随着陆上油田开发难度的不断增大，传统单一的油藏勘探开发方法已经不能满足日益复杂的油藏情况。鄂尔多斯盆地某油田长6^3。油层组属于典型的陆相成因的油气储集层，具有非均质性强、储集层物性差、储量丰度低的特点。介绍了现代油藏描述和油藏数值模拟技术一体化研究思想，针对研究目的层组的地质特征，首先应用随机建模技术建立精细油藏地质模型，并应用网格粗化技术将精细地质模型粗化到油藏数值模拟器能接受的数值模型，最后通过数值模拟中的历史拟合、参数调整步骤，完善地质模型，优化油藏地质认识。生产实际表明，通过一体化技术进行复杂油藏研究能较好解决石油地质研究和油藏工程的衔接问题，能从动态和静态角度研究油藏，为油藏开发的动态预测和方案优化奠定了基础。图5表1参17     

LPG吞吐开采稠油数值模拟研究

通过建立典型区块三维地质数学模型,对冷43断块进行历史拟合,从而确定关键的油藏参数;通过数值模拟技术,对LPG吞吐采油机理以及主要工艺参数的优化进行了研究,并对LPG吞吐生产效果进行了预测.     

基于数据空间反演的油藏实时生产优化方法

油藏开发实时优化调控技术是智能油藏研究的核心内容。提出了基于数据空间反演的油藏实时生产优化新方法,仅需若干油藏模型先验生产动态,基于贝叶斯理论构建代理模型,根据随机极大似然原理拟合历史观测数据进行模型训练,反演得到符合实际观测数据的生产动态后验估计。采用同步扰动随机逼近算法建立生产优化数学模型,实现注采参数实时优化,提高经济开发效益。该方法基于代理模型在拟合阶段避免了重复数值模拟计算,得到正确生产动态后验估计同时兼顾了油藏模型实际地质特征,优化所得方案考虑了目标油藏的不确定性,降低了实际生产开发风险。油藏实例应用表明:该方法能得到与常规多模型数据同化方法相一致的生产动态预测结果,拟合过程计算效率提高了5倍,且注采优化方案能取得良好的驱油效果。提出的油藏开发生产优化设计方法为油田实时生产优化提供了新的思路。     

基于数据空间反演的油藏实时生产优化方法

油藏开发实时优化调控技术是智能油藏研究的核心内容。提出了基于数据空间反演的油藏实时生产优化新方法,仅需若干油藏模型先验生产动态,基于贝叶斯理论构建代理模型,根据随机极大似然原理拟合历史观测数据进行模型训练,反演得到符合实际观测数据的生产动态后验估计。采用同步扰动随机逼近算法建立生产优化数学模型,实现注采参数实时优化,提高经济开发效益。该方法基于代理模型在拟合阶段避免了重复数值模拟计算,得到正确生产动态后验估计同时兼顾了油藏模型实际地质特征,优化所得方案考虑了目标油藏的不确定性,降低了实际生产开发风险。油藏实例应用表明:该方法能得到与常规多模型数据同化方法相一致的生产动态预测结果,拟合过程计算效率提高了5倍,且注采优化方案能取得良好的驱油效果。提出的油藏开发生产优化设计方法为油田实时生产优化提供了新的思路。     

对油气藏工程研究方法发展趋势的几点认识

常用的油气藏工程方法可概括为物质平衡方程、产量递减方程、水驱特征曲线、水驱前缘驱替方程、试井、现代产量递减分析、油气藏数值模拟和产量规划设计优化方法8类,其发展的核心推动力是日趋复杂化的开发对象和持续高效开发的现实需求,以及数学、物理、化学、信息技术和实验手段等学科技术的不断进步。数值模拟方法未来仍为油气藏工程的主流方法,并逐渐向多场、多尺度及地面地下一体化耦合模拟方向发展。分子动力学、LBM等微观、介观流动模拟在油气藏工程中的应用日趋重要,并与传统方法互补,既可揭示开发机理问题,又可为油气藏数值模拟提供参数。解析与半解析方法简单易算、物理意义明确,仍将占据油气藏工程方法的一席之地。另外,伴随大数据与人工智能等新技术的发展,基于数据分析的油气藏工程方法也逐渐成为一个重要方向。