文中老油田剩余油分布的定量预测

文中老油田剩余油分布的定量预测侯高文1　王中良1　王玲云2　邢玉磊3　朱光华3　胡玉江3 (11中国地质大学,北京　21中原油田分公司采油一厂　31中原油田分公司采油二厂)摘　要　文中油田开发已经有20多年的历史,含水、采出程度都较高,稳产形势十分严峻,以往定性的剩余油研究已不能满足油田开发的需要,在油田井网密度较大的情况下,加上多年积累的生产资料,为建立定量的地质模型及应用数值模拟定量预测剩余油提供必要的物质基础。

以油藏精细描述和定量地质模型为基础,结合油藏生产动态、新钻调整井水淹层解释及油井产液剖面、注水井吸水剖面、压力监测等动态监测资料分析为依据,对文留油田文中地区的生产动态进行综合分析和评价。

利用动态分析法定性—半定量地研究剩余油的分布状况,采用油藏数值模拟法全面应用油藏各项静态和生产动态资料,经历史拟合后,模拟得到油藏地下剩余油较精确的定量分布并对将来生产动态给以预测,指导油田的方案部署和剩余油挖潜。

关键词　定量地质模型　油藏生产动态　定量预测　方案部署　剩余油挖潜1　剩余油分布定性研究1.1　C/O测井资料分析统计1998年以后C/O测井资料,结果表明:沙三中7-9砂组只有5.2%的油层厚度和9.7%的层数处于天然能量开采;处于一级水淹的油层厚度为46.1%、层数厚度为38.9%;处于二级水淹的油层厚度为30.4%、层数厚度为30.6%;处于三级水淹的油层厚度为18.3%、层数厚度为20.8%。

可见,沙三中7-9砂组动用状况较好,剩余油主要集中在断层的边角部位。

Ξ1.2　动态综合分析统计1997—2001年13口新调整井、更新井的水淹状况:沙二下油层未被水淹;沙三中4-6砂组只有个别油层水淹;主力含油层沙三中7-9层系未被水淹的油层厚度占35.5%,其中沙三中7层系未被水淹的油层厚度占61.2%;沙三中8层系未被水淹的油层厚度占17.2%;沙三中9层系未被水淹的油层厚度占31.7%。

统计1996—2001年65井次注水井吸水剖面资料结果表明:吸水层层数占总射孔层数的53.9%,吸水层厚度占总射孔层厚度的62.0%,吸水强度大于15m3/d·m的主力层吸水量占总吸水量的47.8%,剩余油主要分布在吸水状况相对较差的小层中[1]。

有吸水剖面的井,小层累积注水量按相对吸水百分数进行劈分;没有吸水剖面的井,小层累积注水按Kh值进行劈分。

充分利用各种监测资料、新钻调整井水淹层解释、产液剖面等资料,动静结合,按小层流动系数Kh值劈分产油量,考虑对应水井吸水状况,产水量主要依据油层的受效情况劈分。

油藏横向上,水井按注入水在平面上所受的流动阻力进行分水,油井按其受效多少为准分产,并参考测试调配资料等,分析油藏水驱过程找出油水运动、分布规律,从而计算各小层的动用状况。

2　数值模拟定量研究剩余油分布2.1　油藏数值模拟模型的建立油藏模拟区共有5个砂层组22个小层,因此纵向上以小层为模拟层,平面上网格划分采用不断块油气田第11卷第4期 FAU LT2BLOCK OI L&G AS FIE LD 2004年7月Ξ收稿日期　2004-03-25第一作者简介　侯高文,1954年生,高级工程师,现从事油田开发研究工作,地址(100083):北京市学院路29号中国地质大学2002级,电话:(010)82310864。

等距的不规则的网格,井位在网格的中心,每两口井之间尽可能的保证有2个以上的网格,边部和局部井位较稀,将断层均处理成封闭边界断层,网格总数为40×54×22=47520个。

地面条件下水的密度:1.0g/cm3;原始油藏条件下地层水的体积系数:1.04;原始油藏条件下地层水的粘度:0.4mPa·s;原始油藏条件下地层水的压缩系数:4.95×10-4MPa-1;原始油藏条件下岩石压缩系数:2.01×10-4 MPa-1;原始油藏温度:118.0℃;标准条件下的温度:20℃;标准条件下的压力:0.1MPa。

选用的黑油模型只接受两相相对渗透率,即油和水与油和气两相,油水相对渗透率曲线选用室内实验数据。

根据取心井所测的相对渗透率曲线,经过归一化处理后得到的相对渗透率曲线。

由于油藏原始状态下不存在原始气顶,因此油气相对渗透率曲线的选取对油藏数值模拟影响不大,每一个网格根据渗透率值的大小选用不同的油水和油气相对渗透率曲线,并根据油藏实际加以适当调整。

流体PVT数据是反映溶解气油比,原油地下体积系数,原油地下粘度,溶解天然气压缩因子,溶解天然气密度和天然气地下粘度随压力变化状态的参数。

选用PVT数据的根据油藏实际生产资料加以修正(见表1)。

表1　高压物性数据压力/　MPa　溶解气油比/(m3/m3)原油体积系数气体因子气体相对密度比重原油粘度/ mPa·s气粘度/0.10 1.08770.90.878 1.330.0040119 1.10820.890.868 1.150.0054 228 1.1280.8820.8600.970.0066 339 1.14670.8770.8520.8680.0077 665 1.18640.8690.8400.760.0093 1098 1.21840.860.8260.6760.0112 12114.5 1.230.8550.8200.650.0123 动态数据是油藏开发过程中与时间有关的数据,其中包括完井数据、油藏监测数据、生产数据等。

完井数据包括射孔与补孔、化学调剖、卡堵水、投产、投注等。

油藏监测数据包括压力监测(单井静压与流压、RFT测试)、生产井产出剖面、注水井吸水剖面、C/O测井等。

生产数据包括产油量、产水量、产气量、气油比、含水、注水量、注气量等。

2.2　历史拟合在建立油藏精细地质模型阶段,虽然已作了大量的工作,但是由于某些参数的不准确性和不确定性,使得模拟产生的动态数据与实际动态数据之间可能有较大的出入。

历史拟合的目的就是应用已有的实际动态数据,对油藏模型加以修改与调整,使模拟产生的动态数据与实际动态一致。

这样应用模拟模型预测的地下流体的分布和未来动态才是比较可信的。

在油藏历史拟合过程中,由于模型参数多,可调自由度大,而实际油藏动态数据有限,不是可以惟一确定油藏模型的参数,为了避免修改参数的随意性,在历史拟合时必须确定模型参数的可调范围,使模型参数的修改在可接受的合理范围内。

其可调参数包括:有效厚度、岩石和流体压缩系数、孔隙度和渗透率、流体PVT性质、相对渗透率曲线、注水井日注水量等。

在进行动态拟合之前,需要对油藏初始状态进行拟合,以确定油藏原始储层参数,根据绘制的等值线图由EXEC UTI VE-ASS OCI ATE前处理系统用一定的插值方法,建立分层节点的网格差分数据,原始地质储量按各小层数据分别拟合,拟合储量与容积法所算储量基本相等,误差较小,说明拟合结果可行,为动态拟合奠定了基础。

油藏历史拟合主要是对压力、含水和气油比等参数随时间变化关系的拟合,对于注水开发的油藏历史拟合最主要的是压力和含水变化历史的拟合,拟合程度的好坏直接影响到未来的动态预测和地下剩余油分布的可信度,拟合程度好,地下剩余油分布准确可靠,未来的动态预测结果可信。

历史拟合包括全油田压力和单井地层压力拟合、全油田压力主要与压缩系数和产出、注水量有关,而地层水的压缩系数和岩石压缩系数可调范围不大,在储量拟合的基础上,拟合全区、单井的采出、注入量,最后全区压力也得到较好拟合。

根据生产历史,对单井、油藏的压力、含水等进行了拟合,模拟区的含水、采出程度与实际基本吻合,即:关键井拟合程度较高;区块生产指标拟2004年7月 断块油气田 第11卷第4期合程度较高。

3　剩余油分类评价3.1　水淹级别的确定根据中国石油天然气公司对水淹级别的统一标准(以含水率划线),进行研究水淹级别,以更准确地研究剩余油分布,挖掘油藏潜力。

对油水相对渗透率资料进行处理,在直角坐标系中作出f w -S w 曲线(见图1)。

图1　f w -S w 曲线 从图中可看出,各种水淹级别含油饱和度界限如下:S o ≤0.46,强水淹;0.46<S o ≤0.55,中水淹;0.55<S o ≤0.65,弱水淹;S o >0.65,未水淹。

3.2　剩余可动油储量丰度分布根据含水率与含水饱和度关系曲线,把含水率98%对应的含油饱和度0.32定为残余油饱和度,利用模拟小层网格剩余油饱和度计算各模拟小层网格剩余可动用饱和度;利用模拟小层网格计算剩余可动油储量丰度。

在纵向上将小层储量丰度相加组成不同砂组、不同层系和区块网格剩余可动油储量丰度。

3.3　分类评价将含油饱和度小于0.45的区域作为水淹区,主要分布在主力油层内,物性一般较好,注采井网较完善或曾经完善过,剩余地质储量有144.8×104t ,占总剩余地质储量的61.6%,可通过水动力学方法进行挖掘,潜力依然较大。

含油饱和度大于0.45的中、弱、未水淹区主要分布在Ⅱ、Ⅲ类油层或动用程度较低的Ⅰ类储层内,剩余地质储量有90.4×104t ,占总剩余地质储量的39.4%,是今后挖潜的主要目标。

4　经济评价利用历史拟合结果的预测模型,预测挖潜方案与不挖潜方案的各项开发指标,通过挖潜方案的实施在2003年到2008年可累积增产原油13.98×104t 。

采用《油气勘探开发经济分析系统》对文中地区增量投资的经济效益分析,评价期10a (2002—2011年),考虑的增量是开发数据和挖潜方案投资。

钻井成本按1502元/m ,原油生产成本按中原油田分公司近两年采油成本资料为基础,原油销售价按1281元/t 计算,财务净现值9728万元;财务内部收益率37.73%;投资回收期2.9a ,具有较好的经济效益。

5　结束语油藏数值模拟模型的建立是决定历史拟合和动态预测的关键。

油藏数值模型设计时,要能代表实际油藏的地质、动态特点,既要能适应油藏历史拟合的需要,又要考虑到将来油藏可能发生的井网调整,以适应未来动态预测的要求。

根据所做剩余可动油储量丰度分布图、单井控制含油面积和可采储量,便可计算各类措施、新钻调整、更新井剩余可动油储量丰度经济界限,为下步调整挖潜提供更加充分的依据。

参考文献1　戴家才1用测井资料确定水驱油藏产层剩余油饱和度1江汉石油学院学报,2002,24(1)2　刘洪涛1利用试井资料研究太南油田剩余油分布规律1江汉石油学院学报,2003,25(2)3　李淑英1文25东断块油藏剩余油分布研究1江汉石油学院学报,2003,25(4)(编辑　滕春鸣)第11卷第4期 侯高文等1文中老油田剩余油分布的定量预测 2004年7月Zh ang F angli and W ang Zh anhong1F ault2B lock Oil&G as Field,2004,11(4):30～32Reserv oir Lei64is a sand2conglomerate bottom water reserv oir,with huge thick pay layer and plentiful reserves abundance.Natural energy,the pay layer characteristic,the oil reserve recovery factor im proved,IPR changing trend,water flood pattern as well as breakthrough time was analyzed and studied by analytics formula and reserv oir simulation in the paper.I t was advised that the Reserv oir L64should adopt tw o sets of develop layers and water flood recovery.Water should be injected in bottom water in lower layer.Different from the antiquity hidden m ountain reserv oir,a sand2conglomerate reserv oir still have the layer characteristic,needing the earnest analysis interlayer. Under the situation of tw o sets of development layers,exact210 meters square pattern,the produce2inject well spacing becomes the main factor in fluencing water flood development result.K ey Words:Sandstone and conglomerate reserv oir, Water flooding development,Massive,Bottom water.I ntegrated R esearch on the Distribution of R em aining Oil in Multi2F ault R eservoirsH e G u anjun(Postgradute School,Southw est PetroleumI nstitute,Chengdu610500,China)1Z eng Xianglin and Su Biaojin et al1F ault2B lock Oil&G as Field,2004,11(4):33～35Pucheng Oilfield is a multi2fault reserv oir,and its heterogeneityresulted in the problems such as the inter ference between different formations and low flooding efficiency.In order to achieve the distribution of remaining oil,we integrated the related subjects and in formation,which proved to be a better way to s olve the problems and built the geological m odel of the oilfield.Based on these w ork,reserv oir simulation was im plemented and achieved the distribution of the remaining oil. The results show that,in the view of plane,the remaining oil is mainly in the high place of reserv oir and no water2flooded place, and in the point of vertical,mainly in the place of low2 quality formation.K ey Words:Multi2fault,Reserv oir,Numerical S imulation, Remaining oil.The Practice and R ealization of Development of the Complicated,Sm all F ault B lock,Mid2low Permeability Oil R eservoir in Jiangsu OilfieldZh ang Zh aolin(The Dep artment of Development, Jiangsu Oilfield Comp any,SIN OPEC,Yangzhou225009, China)and H u ang Wei1F ault2B lock Oil&G as Field,2004, 11(4):36～38By analyzing the geological characterizes of the com plicated,small fault blocks,mid2low permeability reserv oir in Jiangsu oil field,we realize,because of the mid2low permeability,multi2layers,serious heterogeneity,com plicated2 small fault blocks,etc.,there are many developing characterizes such as outstanding con flicts am ong the vertical zones and on the horizontal zone,poor development status of non2dominant layers,poor well pattern,low pressure level and thief water flooding phenomena.In order to res olve the focusing problems, developing technology polices,rational developing style, combination limitation of multi2layer,interval am ong wells as well as water injecting occasion have been researched com pletely.Based on these research results,the development pilots such as the forepart or in2phase injecting water of the new oilfield,the subdividing injecting water of the old oilfield as well,had been put forward.Besides,the development project is designed with the combination zones spanning different oil layer groups.With the practice,great achievements and precious experiences have been acquired for the developing of mid2low permeability,seriously heterogeneity and multi2layer reserv oirs.K ey Words:C om plex and small fault block,Low permeability,Seriously heterogeneity reserv oir,Developing technology policy research,Practice and realization,Jiangsu oil field.Q u atitative Forecast of R esidu al Oil in Developed Wenzhong OilfieldH ou G aow en(China U niversity of G eosciences,B eijing 100083,China),W ang Zhongliang and W ang Lingyun et al.F ault2B lock Oil&G as Field,2004,11(4):39～41Wenzhong oilfield had a development history over20years.I t faces production decrease.The traditional method can not meet the need of development.Quatitative reseach on residual oil is necessary in this phase,and well density is high enough to use numerical simulation.Y ears of production data als o provide physical foundation it.Therefore,analyze and assess the production per formance of wenzhong oilfield on the bases of accurate reserv oir characterization and quatified geological m odel.M oreover,we correct the geology m odel according to production,data from new well,injection profile,pressure testing point out em pirically and even quatitatively in s ome degree the distribution of residual oil.reserv oir numeric simulation pays an vital role in forecast of residual oil.We can predict the production per formance of oilfield in advance,and make development plan to recovery residual oil.K ey Words:Quatitative geology m odel,Production per formance,Quatitative fortecast,Plan im plementation,Residual oil recivery.U sing U nsteady F low Method to C alculate W ater2oil V olume R atio of Edge2bottom W ater R eservoirYou Xiaomiao(Science and T echnology Manage Office, Zhongyu an Oilfield Comp any,Puyang457001,China),Zhou Yu and F ang Zhiw ei et al1F ault2B lock Oil&G as Field, 2004,11(4):42～43Water2oil v olume ratio of edge2bottom water reserv oir presents the capacity of natural energy.I t’s the key to determine reserv oir development scheme and strategy.This article studies geologic static data and production per formance data of actual reserv oir,combining mterial balance equation,using unsteady flow method to calculate water2oil v olume ratio of natural water2drive reserv oir,then determines natural energy and reas onable development scheme,which provides a way for efficient and economic reserv oir developing and plays a certain role for similar reserv oir.K ey Words:Edge2bottom water reserv oir,Unsteady flow, Water2oilv olume ratio,Water cutting.Study on the Perform ance of H ydrophobical Associating W ater2soluble Polymer and surfactant systemLiu Liping(Daqing vocational institute,Daqing P.R. China)and Yang Jianjun.F ault2B lock Oil&G as Field, 2004.11(4):44～45There exists synergistic effect between hydrophobical ass ociating polymer and sur factant,which can im prove theV ol.11　N o.4 ABSTRACT JU LY2004。