稠油油藏提高采收率技术数值模拟研究

渤海地区具有十分丰富的稠油资源,其油藏储层胶结疏松、渗透率高、非均质性严重并且边底水活跃,水驱采收率较低.因此,必须采取调剖、堵水和降黏组合技术措施来进行稠油开发,与其它稠油开发措施相比较,稠油乳化降黏技术具有操作简便和经济性好等优点,其中强化分散体系由于其良好的乳化降黏性以及简易的注入工艺受到石油科技工作者的高度重视.为使稠油乳化降黏技术尽快投入矿场试验,针对渤海普通稠油油藏开发实际需求,以油藏工程理论为指导,以数值模拟方法为技术手段,以正交试验原理安排实验,以A油田B1井组为试验平台,对比了不同开发方式对目标井组开发效果的影响.结果表明,单独注入强化分散体系4个月以上增油效果要好于单独调剖,而调剖与注强化分散体系联合作用效果要明显高于单独调剖与单独注强化分散体系之和,达到了"1+1"大于2的功效;高低浓度注入优于单一浓度段塞;水井调剖和油井堵水会明显增加强化分散体系增油有效期和增油量,推荐水井采取"调剖+强化分散体系高低浓度交替注入"组合措施,油井采取"堵水+强化分散体系吞吐"组合措施。     

JYC油田8106-5井组调剖设计及效果预测

针对JYC油田的8106-5井组进行了调剖设计以及效果预测.首先,应用一种数学方法对调剖半径、调剖剂用量进行理论研究,得到8106-5井组的调剖半径为14.09 m,调剖剂用量为266 m3.接着,对调剖效果进行预测.应用油藏工程方法,确定调剖措施后各层的等效渗透率、吸水量,并通过对平面分配系数以及油井的分层含水率的计算,得到8106-5井组的日产油量为1.24 t.通过对产油量递减规律的研究,得到8106-5井组的调剖有效期和累积增油量分别为358 d和413.35 t.结果表明,研究成果对同类型油田的调剖设计及效果预测的研究有推广应用价值.     

识别非均质油田无效注采井和层的数学模型

多层砂岩油藏注水开发后期,在油水井之间形成了储层高渗透通道,导致注入水沿高渗透通道做无效循环,油井产量下降.为改善注入水驱油效果,必须对无效注采井层实施调剖、堵水等措施,而有效识别无效注采井层是解决问题的关键.优选出了识别无效注采油水井和无效注采层位的判定指标,并建立了用于识别无效注采油水井和无效注采层位的模糊综合评判数学模型.     

特高含水期井震结合注采系统挖潜调整研究

进入特高含水期后,开展注采系统调整挖潜剩余油是油田持续稳产的关键.为了提高特高含水阶段油田采收率,提出井震结合方法精细标定构造层位、认识储层特征,构建地质模型并数值模拟剩余油分布,针对剩余油应用井震结合解释成果设计注采系统调整方案并优化相应注水强度.实验区块研究结果表明:特高含水期,采用井震结合注采系统调整方法最终产油量和采收率分别提高31.21×10~4t和1.54%,能够达到有效挖潜剩余油的目的;而改变注水强度对最终开发效果影响显著,随着注水强度增加,采收率先增大后减小,存在最佳的注水强度为9m~3/d·m.     

同时扰动随机逼近算法在聚合物驱生产优化中的应用

以经济净现值为目标函数,考虑矿场聚合物驱实际特点以及油田注采设备工作能力的限制,建立了考虑约束条件的聚合物驱生产优化模型,并采用同时扰动随机逼近算法进行了高效求解.结果表明,建立的聚合物驱生产优化模型以及基于同时扰动随机逼近算法的求解方法能够辅助聚合物驱油藏开发方案的优化制定,对于高效合理开发有限石油资源、提高聚合驱项目的经济效益具有重要意义.     

缝洞型碳酸盐岩油藏注水驱油提高采收率研究

Y油田为缝洞型碳酸盐岩油藏,油藏复杂的地质特征决定了其开发模式有别于常规砂岩油藏.为了有效提高Y油田采收率,利用Eclipse数值模拟软件建立了地质模型,对水平井长度、射孔间距及酸压缝长等油藏产能影响因素与转注时机、注采比以及关井时间等注采参数进行了优化.结果认为:对于Y缝洞型碳酸盐岩油藏,水平井水平段长度为500m、射孔间距为20m或酸压规模为100m时,累计产油量可达到最大值;压力降至废弃压力时进行转注,可获得最大采收率;周期注采比等于1时,周期时效与累计增油量达到最大值;关井时间为8天时,采收率提高幅度最大.     

努拉里边底水油气藏提高采收率注采制度优化方法

开发边底水油气藏关键因素是抑制边底水锥进,延长油井无水采油期以提高油藏采收率,因此需要设置合理的开采速度和油水井注采制度.为深入了解不同井网系统和注采参数对边底水油气藏开发效果的影响程度,针对努拉里边底水油气藏开展研究.对边底水影响程度进行研究,得到各井在改变水体倍数后,以含水率差值4%为界限定义受边底水影响程度强弱,差值超过4%则定义为强水侵井,反之则为弱水侵井.在此基础上,采用油藏工程和数值模拟方法优选了注采参数,得出最优井距为1000m,最佳日注水量为30m³/d,最佳采液速度为4.75%-5%,并对优化参数进行了模拟预测,优化后累计产油量增加1.98×10⁴t,采收率达到54.7%.运用油藏工程方法对优化后的开发方式调整进行了分析,结果表明:可采储量采出程度小于62.78%时应以扩大波及体积为主,大于62.78%后应以增加驱油效率为主,目标区块优化后可采储量采出程度达到71.3%,相对潜力值i=0.81<1,处于开发后期,此时开发方式应以提高驱油效率为主.研究成果为同类边底水油气藏前期开发和后期措施调整提供了理论指导和借鉴.     

吸水体膨颗粒与油藏适应性评价

针对矿场调剖实际需求,利用仪器检测和物理模拟方法,开展了体膨颗粒吸水率与溶胀率、抗剪切性、渗流特性、传输运移能力、粒径与油藏孔隙匹配关系和驱油效果实验研究.结果表明:随时间延长,体膨颗粒吸水率和溶胀率增大,并且初期增幅较大,24小时后增幅减缓.体膨颗粒抗剪切性能较好,经地层剪切后83%以上仍为大颗粒.体膨颗粒粒径愈小,溶剂水矿化度愈低,吸水率和溶胀率愈大,抗剪切能力愈差;与污水相比较,污水配置聚合物溶液中体膨颗粒吸水率和溶胀率较小,抗剪切性较好,当体膨颗粒浓度为6000mg/L时,"体膨颗粒粒径/平均喉道直径"范围在4.18~5.40之间可适用于油藏.推荐体膨颗粒浓度6000mg/L,注入量0.38PV,调剖半径51.3m,为避免封堵近井地带,可先选择小粒径颗粒注入,并逐渐增大粒径.     

同井注采井本井提高采收率潜力研究

基于国内外同井注采的理论和实践、各个国家的同井注采技术的发展水平、以及陆上油田的含水率越来越高这一现状,同井注采技术必将成为一个大趋势.首先列出了预测同井注采技术相比较于水驱的潜力计算公式.已知每个时刻的含水率,由相对渗透率曲线求得含水饱和度,再根据公式计算出平均含水饱和度,进而求出采出程度.根据经济极限含水率、经济极限采出程度这两项指标,针对18口同井注采试验井,当油价为50$/bbl时,由水驱经济极限含水率生产至同井注采经济极限含水率,平均采出程度增幅3.95%,当油价为70$/bbl时,平均采出程度增幅4.62%.     

一种预测注采关系调整效果的数学模型

在油田开发过程中,由于某些油层的注采关系并不完善,需要补充注水井调整注采关系,为了实现对注采关系调整开发效果的预测,本文利用劈分方法、注采平衡原理、油水两相非活塞式水驱油理论等理论方法,推导出了一套计算注采关系调整开发效果的数学模型,利用该模型对大庆油田注采关系调整试验区的G161-483井进行了实例计算.根据劈分方法,计算得出G161-483井的4口受效井的劈分系数,分别为0.28、0.12、0.43、0.17.由G161-483井产油量与累产油量的关系得出水驱极限累产油量为0.0750×10~4m~3,注采关系调整极限累产油量为0.6395×104m3,计算得到增油量为0.5645×10~4m~3.由受效井产油量与累产油量的关系得出,该井的水驱极限累产油量为12.5023×10~4m~3,注采关系调整极限累产油量为13.4416×10~4m~3,计算得到注采关系调整技术增油量为0.9393×10~4m~3.最终得出了注采关系调整技术总的增油量为1.5038×10~4m~3.结果表明,注采关系调整技术能够有效地延长经济极限开发有效期,提高波及体积,增加生产期的累产油量,从而提高采收率.     

Effect of the chemical structure of the polymer matrix on the properties of foam polyurethanes at low temperatures

The dependence of physical and mechanical properties of oligoether-based foam polyurethanes on the molecular mass (M_c) of polymer chains between the nodes of the polymer network and on the content of rigid segments in the polymer is investigated at 293 and 98K. The values of M_c at which the foam plastics have the best mechanical properties at low temperatures are determined. The content of rigid segments in the polymer at which foam polyurethanes have the best combination of the linear thermal expansion coefficient and mechanical properties in tension at a temperature of 98K is found.Latvian State Institute of Wood Chemistry, Riga, LV-1006, Latvia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 4, pp. 517–526, July–August, 1999.     

基于隐式离散极大值原理的聚合物驱最优注入策略

为了获得聚合物驱油的最大利润,建立了确定最佳聚合物注入浓度的最优控制模型.利用全隐式差分格式将连续模型离散化得到离散系统的状态方程.通过隐含离散系统的极大值原理获得了该最优控制问题的必要条件.给出了基于梯度的数值求解方法,在求解状态方程的过程中直接构造了伴随问题的系数矩阵.通过一个三维聚合物驱模型的计算实例表明了所提出方法的可行性和有效性.     

Transport of Mass,Momentum and Energy through Periodic Open Cell Metal Foams Applied in Catalysis

An ODE model to predict the temperature field of periodic open cell metal foams applied in catalysis as carrier structures is presented. The catalytic and highly endothermic reaction takes place in a porous layer which surround the struts of the foam and releases gas from a fluid. The one-dimensional model includes dependencies of the foam structure (strut radius, shape of strut), process conditions (surrounding velocity, surrounding fluid: liquid and/or gas), chemical conditions (reaction enthalpy, activation energy) and material parameters (thermal conductivity, density, viscosity). This makes it possible to estimate optimal parameters, that are able to provide sufficient heat to the reaction. The advantage of this model is the substantial time saving in contrary to three dimensional finite volume simulations. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

聚合物混合质量的智能控制

聚合物与填料的混合质量，直接影响聚合物成品质量，混合质量的在线控制并优化控制参数已成为保证聚合物成品质量的关键。本文首先建立基于填料颗粒面积与位置分布为判断指标的填料等级识别模型，并借助计算机与数字图形处理技术获取填料混合质量的信息，在此基础上建立了聚合物混合参数的优化控制模型，仿真检验的结果表明，模型是合理的，且与投入使用的同类仪器相比具有更满意的结果。     

Collapse criteria of foam cells under various loading

Recently porous materials are widely used in civil and mechanical engineering. In particular, such porous materials as metal and polymer foams have applications in lightweight structures. From mechanics point of view foams can demonstrate unusual behavior such as strain localization related to foam cells buckling under certain loads. The aim of this work is the elaboration of the model of foam material taking into account the cell collapse. We consider the cell collapse initiation during the elastic instability and its further evolution under loading. The geometrical structure of foam is generated with the use of the Voronoi algorithm. Based on stochastic distributions of cells we create various geometrical models of foams. The influence of the cell volume, wall thicknesses and material properties of the foam material on critical loads is obtained. The calculations are performed with the use of Abaqus CAD/CAE system. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Operation strategy optimization of desulfurization system based on data mining

Desulfurization systems in coal-fired power stations often suffer the problem of high operating costs caused by a rule-of-thumb control strategy, which implies great potential for optimization of the operation. Due to the complex desulfurization mechanism, frequently fluctuating unit load, and severe disturbance, it is challenging to determine the optimal operating parameters based on the traditional mechanistic models, and the operating parameters are closely related to the operational efficiency of the flue gas desulfurization system. In this paper, an operation strategy optimization method for the desulfurization process is proposed based on a data mining framework, which is able to determine online the optimal operating parameter settings from a large amount of historical data. First, Principal Component Analysis (PCA) is used to reduce data redundancy by mapping the data into a new vector space. Based on the new vector space, an enhanced fuzzy C-means clustering (Enhanced-FCM) is developed to cluster the historical data into groups sharing similar characteristics. Taking sulfur dioxide emission concentration as a constraint condition, the system is optimized with economic benefits and desulfurization efficiency as the objective function. When performing optimization, the group that current operating conditions belong to is determined first, then the operating parameters of the best performance are searched within the group and provided as the optimization results. The method is validated and tested based on the data from a wet flue gas desulfurization (WFGD) system of a 1000 MWe supercritical coal-fired power plant in China. The results indicate that the proposed operation strategy can appropriately obtain operating parameter settings at different conditions, and effectively reduce the desulfurization cost under the constraint of meeting emission requirements.     

Sensitivity of a shallow-water model to parameters

An adjoint based technique is applied to a shallow water model in order to estimate the influence of the model’s parameters on the solution. Among parameters, the bottom topography, initial conditions, boundary conditions on rigid boundaries, viscosity coefficients, Coriolis parameter and the amplitude of the wind stress tension are considered. Their influence is analyzed from three points of view:

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flexibility of the model with respect to a parameter that is related to the lowest value of the cost function that can be obtained in the data assimilation experiment that controls this parameter;

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possibility to improve the model by the parameter’s control, i.e., whether the solution with the optimal parameter remains close to observations after the end of control;

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sensitivity of the model solution to the parameter in a classical sense. That implies the analysis of the sensitivity estimates and their comparison with each other and with the local Lyapunov exponents that characterize the sensitivity of the model to initial conditions.

Two configurations have been analyzed: an academic case of the model in a square box and a more realistic case simulating Black sea currents. It is shown in both experiments that the boundary conditions near a rigid boundary highly influence the solution. This fact points out the necessity to identify optimal boundary approximation during a model development.