Linear flow simulated by traditional productivity simulation method when determining gas reservoir property cutoffs is inconsistent with radial flow in actual field single well production, and the assumption that gas velocity at outlet of core is equal to gas velocity in field wellbore is inconsistent with similarity criterion required by physical model. By improving experiment method for linear flow, i.e. radial flow simulation method, new experimental equipment is designed to simulate areal radial flow which is more in line with actual streamline of gas reservoir. Gas flow rate obtained from lab radial flow experiment is transformed to field conditions according to similarity criterion so as to more realistically evaluate flow capacity of target reservoir and finally obtain property cutoffs that conform to productivity characteristics of target gas reservoir. The results show that gas well productivity obtained by improved radial flow productivity simulation method is increased by 100 times higher than that of linear flow productivity simulation method before improvement. Property cutoffs obtained by improved radial flow productivity simulation method is lower, which is more in line with actual production situation with low porosity and low permeability but high single well productivity of ultra-deep carbonate gas reservoir in Member 4 of Dengying Formation in Gaoshiti-Moxi Block. The research results can more accurately evaluate property cutoffs of ultra-deep carbonate gas reservoirs.
In order to overcome the evaluation distortion of conventional evaluation method for retrograde condensate damage, which ignores near-wellbore retrograde condensate superposition effect and far-wellbore single phase condensate gas flow characteristics, based on long-core displacement experiment, a new evaluation method is established considering superposition effect and far-well single-phase flow, simulating retrograde condensate damage of shale reservoir in actual depletion development and evaluating retrograde condensate removing effect of the injections of methanol, dry gas and CO 2 . Influence of CO 2 injection volume and injection pressure on evaluation indexes of retrograde condensate damage is studied. Experiment results show that, when the pressure drops to the maximum retrograde condensate pressure, gas permeability damage rate is 80.2%～83.1%, with displacement pressure difference rapidly increasing from 5 MPa to 15 MPa and gas flow resistance increasing by 200%. After CO 2 injection, gas permeability increases by 3.2 times with gas-oil ratio changing rate of 23.1% and core differential pressure decreasing rate of 36.1%, verifying that CO 2 injection has the best effect, followed by methanol, and dry gas injection has the worst effect. The optimal injection pressure of CO 2 is 9 MPa with injection volume of 0.15 PV and oil-gas equilibrium time of 9.9 h. The research provides ideas and methods for efficient development of shale condensate gas reservoirs and retrograde condensate damage removal.
目前已有关于裂缝的研究主要是地震单属性预测,裂缝预测的精度较低.为了进一步提高压裂改造水平与页岩气井产能,需对页岩储层不同尺度的裂缝进行预测,尤其是对小尺度裂缝进行精细预测.利用相干、曲率、蚂蚁体3种地震属性对永川地区龙马溪组一段的天然裂缝进行定量预测,并针对不同尺度裂缝进行多属性裂缝综合建模.结果表明:永川地区裂缝分为3个等级,断距大于100 m的大尺度裂缝、断距50～100 m的中尺度裂缝和断距小于50 m的小尺度裂缝,相干、曲率、蚂蚁体属性预测结果大体一致,整体上断层走向以NE—SW为主,大尺度裂缝主要发育在新店子背斜附近,蚂蚁体可以更清晰地刻画出小尺度裂缝.裂缝综合建模显示,永川地区深层页岩气储层总体裂缝发育程度由好到差依次为新店子背斜主体、南部向斜、北区向斜,南部向斜微裂缝最发育,有利于压裂改造,因此将永川南部作为首要滚动产建目标区,气井试采效果好,测试产量整体高于永川中、北区.研究成果对于实现永川地区页岩气增储上产具有一定的指导意义.
为了解决页岩油组合粒径+滑溜水的支撑剂加砂工艺中裂缝有效支撑差、导流能力弱的问题,建立支撑剂粒径分布的稠密离散相模型(DDPM),研究压裂主缝中组合粒径支撑剂加砂运移及铺置规律,并基于运移规律模拟结果,开展劈裂页岩岩板组合粒径不同铺置模式下的室内导流能力评价.结果表明:滑溜水携砂液体系下,裂缝内支撑剂叠置铺置时,后注入的支撑剂叠置于先注入支撑剂的顶端,且先注入的支撑剂会被后续注入的支撑剂向远端推移一定距离;组合粒径中粒径配比差异对于支撑剂运移形成的砂堤形态影响较小;大粒径组合逐级注入的方式更利于支撑剂在近缝口和裂缝内垂向铺置;在低闭合压力(p≤40 MPa)、铺砂浓度5kg/m2条件下,沉降铺置方式最利于提高裂缝导流能力,其次为混合铺置,分段铺置方式最差;高闭合压力下(p＞40MPa),铺置方式对裂缝导流能力影响较弱.综合支撑剂运移模拟和导流能力评价结果,建议吉木萨尔页岩油组合粒径加砂工艺采用逐级注入的方式,并保证组合粒径中大粒径拥有较大配比.
砂地比是表征储层侧向输导能力的重要参数,基于线性回归方法结合地震属性预测砂地比易受数据间非线性关系影响,且样本量较少,预测误差较大.以束鹿凹陷束21井区为例,研究了馆陶组砂地比平面分布趋势,通过细分层方法扩充数据样本规模及平滑因子滤波手段对地震属性进行"毛刺"平滑处理,采用皮尔逊相关性优选地震属性,结合多种地震属性和井点砂地比统计数据,使用随机森林算法预测砂地比.结果表明,随机森林法可以有效处理非线性结构数据,与线性回归、神经网络(MLP)对比,模型误差明显降低,预测精度可达80％.该方法的预测结果已成功应用于实际钻井中,且取得了显著的效果.
生产指数是水平井压裂后生产能力评价的重要指标,目前非常规油气水平井压裂后产能预测方法较复杂,参数较多,需进一步优化设计.基于统一压裂设计理论的支撑剂指数法,借用支撑裂缝流动效率优化无因次裂缝导流能力及无因次生产指数,采用多元线性回归方法建立了水平井长度、裂缝半长、裂缝条数、井控边界、储层厚度5种因素影响下的最优无因次裂缝导流能力及无因次生产指数计算模型.结果表明:利用新建模型回归的最优无因次裂缝导流能力多元线性方程决定系数R2为0.933,回归的无因次生产指数多元线性方程决定系数R2为0.980,平均相对误差均小于5％,与传统预测方法相比,精度有了明显的提高.敏感性分析结果表明,生产指数与水平井长度、裂缝条数、裂缝半长和储层厚度呈正相关,与矩形渗流区域长度呈负相关,其中与裂缝条数的关联性最强.研究成果对快速实现非常规油气水平井压裂后产能准确预测、经济评价和施工参数优化都具有重要意义.
High-dip reservoirs in Hailar Oilfield have large amount of proved OOIP, and reserves with stratigraphic dip of ＞10° account for 68.6% of the total proved OOIP. Affected by structural relief, conventional water flooding development cannot realize balanced displacement of wells in top and bottom of structure. Water cut in producers at the edge and bottom increases rapidly, while producers in structural high get less response, with ineffective overall development. Aiming at the problem of poor water flooding development effect of high-dip fault block reservoir in Hailar Oilfield, based on laboratory oil displacement experiment of CO 2 gravity drainage and using reservoir numerical simulation method, the mechanism, influencing factors and applicability of CO 2 gravity drainage are studied.The results show that CO 2 displacement efficiency reaches 55.9% with 1.2 PV CO 2 injected at initial formation pressure of 10.57 MPa, greatly improving the recovery of high-dip fault block reservoir. Stratigraphic dip, reservoir permeability and gas injection rate are the main factors affecting the effect of CO 2 gravity drainage. Hailar Oilfield has 4 411.35×10~4 t of proved OOIP suitable for gravity drainage development. CO 2 gravity drainage technology has broad application prospects in Hailar Oilfield.
为了研究含油气盆地上覆无源储盖组合油源断裂处油气分布规律,在对上覆无源储盖组合油源断裂运聚油气机制及其部位研究的基础上,利用油源断裂输导部位和下伏已聚集油气部位耦合,确定油源断裂运聚油气部位,再结合下伏区域性泥岩盖层渗漏部位,确定下伏供油气部位,最后与上覆区域性泥岩盖层封闭部位相组合,建立一种上覆无源储盖组合油源断裂运聚油气部位预测方法,并利用此方法预测渤海湾盆地歧口凹陷上覆馆陶组—明化镇组储盖组合港东断裂运聚油气部位.结果表明:上覆馆陶组—明化镇组储盖组合港东断裂油气运聚部位主要分布在其中部和东部,有利于下伏沙三段已聚集油气在上覆馆陶组中运聚成藏,与目前港东断裂处馆陶组已发现油气分布相吻合,表明该方法用于预测上覆无源储盖组合油源断裂运聚油气部位是可行的.该成果为推测上覆无源储盖组合油源断裂运聚油气部位奠定了理论基础.
针对天然气压缩因子计算模型的适应范围小、计算误差大、模型拟合系数多和不连续等问题.利用非线性曲面拟合工具,选用微分形式简单的函数形式,对Standing-Katz图版的低压区和高压区的8 340组数据进行非线性曲面拟合.结果表明:新模型在0.2≤ppr≤30.0(ppr为对比压力)、1.05≤Tpr≤3.00(Tpr为对比温度)时,拟合的卡方容差值为2.574×10-4,平均相对误差(RARE)、平均绝对误差(RAARE)、均方根误差(RRMSE)、标准误差(RSD)和相关系数(R2)分别为0.170％、1.260％、0.015％、0.340％和0.996;该模型为显式计算模型,不需要迭代计算,计算速度快、计算精度高,且具有函数形式简单、拟合系数单一、适用温度压力范围大和连续可微的优点;经过对干气、凝析气和酸性天然气等3类天然气实例验证,平均绝对误差分别为0.527％、0.809％和0.110 9％.该模型为在宽温宽压范围内快速准确地预测天然气压缩因子提供了一种新手段,为温度压力连续模拟和天然气热力学参数计算奠定了基础.
在利用常规测井曲线对厚层砂砾岩储层进行层序细分的过程中,存在界面不清楚、划分标准难以确定的问题,而米兰科维奇旋回作为沉积地层中的一种重要地质事件,在漫长的地质历史时期中具有相对的稳定性,这种特性使得在米氏旋回约束下的层序划分具有更高统一性.利用变分模态分解(VMD)方法对松辽盆地徐家围子断陷营城组四段(营四段)厚层砂砾岩地层中米兰科维奇旋回进行时频分析,提取与米兰科维奇天文周期对应的高频分量,从而实现层序的划分.结果表明:使用变分模态分解(VMD)方法对测井曲线进行处理,对研究区自然伽马曲线进行VMD分解可得到若干个特征分量,通过对比,100ka周期对应IMF1分量;根据IMF1曲线形态并结合岩性将营四段细分为21个五级层序,并将其组合为6个四级层序,在四级层序界面处,曲线形态发生明显的突变,表现出明显的周期振荡并且有较大的响应幅度.VMD方法在营四段的应用表明,此方法能够对不同尺度的米兰科维奇旋回进行精准识别和划分,并具有较高的精度和可重复性,研究成果可用于砂砾岩地层的高频层序划分.
In order to understand storage effect of CO 2 huff-and-puff in fractured shale reservoirs and explore feasibility of effective CO 2 storage by CO 2 huff-and-puff,a numerical model of CO 2 huff-and-puff and storage of shale oil wells with complex fracture networks is established for comparison of characteristics of huff-and-puff and storage with different production parameters and fracture parameters.Grey correlation analysis method is introduced to determine main controlling factors of CO 2 huff-and-puff and storage.The results show that CO 2 huff-and-puff can not only improve shale oil recovery,but also achieve effective storage of partial CO 2 with storage coefficient of 0.40.When CO 2 huff-and-puff is used in shale oil reservoirs development,the effect of huff-and-puff and storage is improved with increment of production parameters including huff-and-puff rounds,injection rate,soaking time and cyclic injection volume,among which huff-and-puff round has the most influence on huff-and-puff effect with cumulative oil production increased by 22.12%,and injection rate has the most influence on storage effect with storage coefficient reaching 0.40.The later the CO 2 huff-and-puff is,the less can the cumulative oil production is,and the higher the storage coefficient is,with cumulative oil production decreased annually by 3.47%per year and storage coefficient increased annually by 39.48%.Increase of number and length of fractures in shale reservoir is beneficial to improve oil recovery and achieve more CO 2 storage,with cumulative oil production increased maximally by85.18%and storage coefficient increased maximally by 20.90%.The research has reference significance for field practice of enhanced oil recovery by CO 2 injection in shale oil reservoirs.shale oil CO huffandpuff CO storage complex fracture network grey correlation
Due to the limitation of surface conditions,it is difficult to conduct regular sampling for seismic data collected in the field,and irregular sampling of seismic data affects seismic data processing and interpretation. To solve this problem,matching pursuit Fourier interpolation algorithm is used to reconstruct irregular seismic data, and iterative part of interpolation algorithm is improved,so that it only calculates Fourier coefficient spectrum in frequency wavenumber domain,reducing a large amount of forward and inverse Fourier transforms in iteration,so as to reduce calculation time of matching pursuit Fourier interpolation algorithm. The improved method is applied to forward seismic records of random undersampling graben,Marmousi forward seismic records and actual CMP seismic data for regular reconstruction. The results show that improved matching pursuit Fourier interpolation algorithm can regularize random undersampling seismic data. After reconstruction,its events becomes continuous,frequency spectrum energy converges,and effective signal are recovered. Moreover,the reconstruction time of improved algorithm is significantly reduced,and its acceleration ratio is more than 30 times,indicating the correctness and feasibility of the method. Improved matching pursuit algorithm provides new theoretical basis for reconstruction of irregular seismic data.
针对传统线性特征的驱替曲线都不再适用于特高含水期油藏的情况,提出了一种综合含水率和采出程度之间的非线性关系方程式,可直接描述特高含水期油藏宏观开发指标变化规律或驱替特征.结果表明:不管油藏曾经历的开采历史是否存在水驱井网加密、聚合物驱等重大调整措施,只要油藏在特高含水期处于相对平稳的开发状态,采出程度与综合含水率呈非线性关系.所提非线性关系得到了水驱油藏概念模型模拟结果的验证,已用于含聚驱历史真实油藏开发后期的指标分析.对于陆相大型油田的部分开采单元及其整体,该关系在特高含水期大部分呈现出90％以上的符合率,由此得到了值得油田中长期规划参考的含水上升率、递减率、采收率等开发指标预测结果.
为明确纳米颗粒对原油中沥青质沉淀的抑制效果及吸附沥青质机理,采用X射线衍射、傅里叶变换红外光谱、场发射扫描电子显微镜和低温氮气吸附实验方法,开展了沥青质起始沉淀点测定实验和沥青质溶解线及沉淀线测定实验,研究了改性F-SiO2纳米颗粒作用下的沥青质起始沉淀点、吸附量及亚稳定区宽度的变化.结果表明:纳米颗粒对轻质油中沥青质的吸附以单层为主,最大吸附量为0.8 g/g,而对重质油中沥青质的吸附以多层和大颗粒沥青质聚集体(10～50μm)为主,最大吸附量可达8.6 g/g;F-SiO2纳米颗粒增大了沥青质的亚稳定区,推迟了沥青质自发成核的形成时间,延迟了沥青质起始沉淀点,抑制了沥青质沉淀;F-SiO2纳米颗粒作用下的重质油沥青质的燃烧残余物质量分数为11.6％,优于轻质油沥青质(52.8％),证明F-SiO2纳米颗粒对重质油中沥青质的吸附及抑制效果好于轻质油.研究成果为预防沥青质沉淀、缓解沉积伤害提供了理论依据.
朝阳沟油田杨大城子油层杨二段致密砂岩储层具有单层厚度薄、横向变化快的特点.为明确砂体展布特征,采用基于波形相控的波形指示模拟地震储层预测方法,在储层敏感参数模拟反演的基础上,实现致密薄砂层高精度识别与预测.结果表明:自然伽马波形指示模拟结果具有较高的纵、横向分辨率,薄砂层的厚度识别精度可达到3m,反演结果与井下钻遇砂体符合率为87.1％,能有效反映了薄砂层空间展布特征,实现薄砂层空间分布预测;杨大城子油层杨二段砂体发育受沉积微古地貌的起伏形态控制,杨二下段砂体分布特征与沉积微地貌具有良好的匹配关系,砂体分布广泛且厚度较大,杨二上段砂体分布特征不受沉积微地貌控制,砂体发育较差且厚度明显减薄.研究成果对杨大城子油层致密薄砂岩的预测提供了有力支撑,同时对类似地质条件的地区及目标层段具有借鉴和指导意义.
黑龙江省兰西地区Xr7井三叠系老龙头组揭示了一套紫红色、绿灰色和灰色砂泥岩沉积地层,为了获取这套杂色砂泥岩沉积环境信息,对钻井岩石样品的痕量元素、稀土元素进行了检测和综合应用研究.结果表明:老龙头组沉积岩中轻、重稀土元素分异程度较高,δEu表现为显著负异常、δCe无异常,球粒陨石标准化配分模式图总体表现为轻稀土富集、右倾,重稀土亏损、近平坦型;痕量元素Sr、Cu质量分数及其比值w(Sr)/w(Cu)等在剖面上波动变化表明老龙头组沉积时期的古气候经历由早期干旱炎热到晚期温暖湿润的一个气候变迁过程;w(Li)、w(Sr)、w(Ga)以及w(Sr)/w(Ba)等指标综合研究表明,老龙头组沉积时期水体主要为淡水环境;氧化还原环境判定指标w(Ni)/w(Co)、w(V)/w(Cr)、w(U)/w(Th)、δU、δEu和δCe等综合研究表明,研究区三叠系沉积时期主体为氧化环境.研究成果为后续勘探开发提供地质理论指导.
With the increase of huff-and-puff rounds of heavy oil reservoir, components with low viscosity are preferentially extracted. High viscous flow-restricted ring is formed around near-wellbore zone, reducing reservoir permeability and causing continuous low level of cyclic oil production, cyclic fluid production and cyclic oil-vapor ratio. In order to understand the formation mechanism of flow-restricted ring and its influence on fluid flow, physical simulation and numerical simulation methods are used to study heavy oil property and flow characteristics, and variation characteristics of viscosity field, temperature field, pressure field and saturation field influenced by flow-restricted ring of different cycles. The results show that light components are recovered and heavy components are retented after multi-rounds huff-and-puff. In near-well zone with radius of 40～60 m, circular high-viscosity flow-restricted ring is formed, mainly composed of heavy components such as asphaltene and colloidal matter, and its width increases with the increase of huff-and-puff rounds. Flow-restricted ring reduces reservoir flow capacity and affects distribution characteristics of flow field in reservoir, shielding heavy oil flow in far-well area, consequently, causing difficult mobilization of interwell oil. In order to eliminate unfavorable effect of flow-restricted ring, 2 kinds of productivity-released production technologies for efficiency promotion and improvement,“preposition-fluid viscosity reduction+high pressure agitation” and “ high efficient viscosity reduction+gas energy increasing ”, are developed based on “flow-restricted ring” distribution. The research provides experimental support and theoretical basis for continuous high-efficiency development of multi-rounds huff-and-puff heavy oil reservoirs.
为给老油田提供增产新技术,以适用于大庆油田的新型聚表剂为例,探索聚合物-表面活性剂驱油技术,利用红外光谱和扫描式电子显微镜对比Ⅰ型、Ⅱ型2种聚表剂的分子结构和微观形貌差异,结合增黏性、抗剪切性、耐盐性以及乳液稳定性、渗流特征、驱油动态性能等,研究聚表剂的构效关系.结果表明:Ⅰ型、Ⅱ型聚表剂的基础结构均是聚丙烯胺;Ⅰ型聚表剂分子链具有立体网状结构,具有更粗壮的链条,其增黏性能、耐盐性能和抗剪切性能均优于Ⅱ型聚表剂;Ⅱ型聚表剂分子链以平行的形式排列,其空间网络结构复杂,乳化性能更佳,Ⅱ型聚表剂具有较低的阻力系数以及驱油注入压力,其与储层的匹配性较好,所以在相同条件下Ⅱ型聚表剂的采收率比Ⅰ型聚表剂高4.52百分点,具有更好的提高采收率效果.研究成果可为改善聚驱效果提供新的技术手段.
火驱是一种高效、环保、低成本的稠油开采技术,具有良好的应用前景.原油黏度对火驱采油效果的影响仍缺乏规律性认识,需要进一步研究.利用新疆、河南和辽河油田的3种稠油研究了原油黏度对火线推进、燃烧前缘的稳定性和火驱开采效果的影响.结果表明:黏度大的原油在火驱过程中产出的COx浓度高,燃料消耗量大,驱替压差高,火线推进速度小,采油井的见效时间晚,油墙的有效厚度小,最终采收率低;依据不同黏度原油火驱过程中的累计产油量、产出气体浓度和驱替压差的变化规律,可将火驱开采过程划分为点火、可动油流动、油墙形成、快速产油和火驱结束5个阶段.研究成果可为火驱技术在不同原油黏度油藏中的现场应用提供重要的参考依据.
牙哈地区吉迪克组滩坝砂体埋藏深、高砂地比且单层厚度薄,分布规律复杂,地震测井分辨率难以识别和追踪,在进行砂体精细刻画以及预测评价方面有着较大难度.基于牙哈地区新近系吉迪克组底砂岩段岩心、测井等资料,对滨浅湖滩坝微相及岩性组合进行精细刻画,分析了滩坝迁移规律及控制因素.结果表明:研究区吉迪克组底部砂岩段滨浅湖滩、坝亚相可进一步划分为坝中、坝缘、滩席和滩间微相类型;滩坝的展布、迁移叠置受湖岸线、古地貌、古风浪及沿岸流等因素控制,先随湖水不断加深坝体向岸迁移,直至湖平面稳定时期大量泥质沉积,而后湖平面下降坝体呈向湖中心进积模式;其岩性组合可划分为4类:厚层砂岩叠置组合(A类);中-厚层砂岩夹薄层泥岩组合(B类);薄层泥、砂岩互层组合(C类);厚层泥岩夹薄层砂岩组合(D类).研究成果为滨浅湖滩坝砂体研究提供了新的参考.
