塔河油田碳酸盐岩缝洞型油气藏注水替油开发研究

塔河油田奥陶系碳酸盐岩缝洞型油藏非均质性强、油水分布规律差。部分高产井易水淹或产量大幅度递减。在生产实践中,发现部分单井在压井后,压力明显上升、可以恢复部分产量。分析奥陶系碳酸盐岩缝洞型油藏储层特征,研究注水开发的地质影响因素,并通过对注水替油的机理研究,结合现场单井注水替油和多井缝洞单元注水替油的实践,来分析选井、选层及注采参数的影响,评价注水替油开发效果,优化注水方案设计,是为了使注水开发在塔河碳酸盐岩油藏的推广应用,以便提高油田采收率。     

Integrated Reservoir-Based Canal Irrigation Model. I: Description

The success of irrigation system operation and planning depends on the quantification of supply and demand and equitable distribution of supply to meet the demand if possible, or to minimize the gap between the supply and demand. Most of the irrigation literature mainly focuses on the demand and distribution aspects only. In addition, irrigation projects that receive water from a reservoir can be challenging to manage as annual fluctuations in runoff from the reservoir’s catchment can have considerable impact on the irrigation management strategy. This study focuses on the development of an integrated reservoir-based canal irrigation model (IRCIM) that includes catchment hydrologic modeling, reservoir water balance, command hydrologic modeling, and a rotational canal irrigation management system. The front end of the IRCIM is developed in Visual Basic 6.0, whereas the back-end coding is done in C language. The graphical user interface is the most important feature of the model, as it provides a better interaction between the model and its user. The IRCIM has a modular structure that consists of three modules, viz., catchment module, reservoir module, and crop water demand module. The catchment module predicts daily runoff from the catchment that inflows to the reservoir. Depending on the data availability, this module is provided with the flexibility of choosing between the Soil Conservation Service’s curve number method combined with the Muskingum routing technique, and an artificial neural network technique using the Levenberg–Marquardt algorithm. The reservoir module is based on conservation of mass approach, and results in daily reservoir storage. The crop water demand module is comprised of water-balance models for both paddy and field crops. The irrigation management system serves as the program flow controller for the model and runs the required module when needed. For postseason evaluation of the irrigation system, performance indicators such as adequacy, efficiency, equity, and dependability are used. In a companion paper, the model is applied for Kangsabati Irrigation Project, West Bengal, India.     

Three-Dimensional Modeling for Estimation of Hydraulic Retention Time in a Reservoir

A three-dimensional computational fluid dynamics model is used to estimate the hydraulic residence time for a portion of the Wachusett Reservoir in central Massachusetts. The basin under consideration has several major inflows and exhibits complex flow patterns. The basin is modeled using the FLUENT software package with particles used to track travel time in a steady-state flow field. A tetrahedral mesh with over 1.6 million cells is used with accurate depiction of basin bathymetry and inlet and outlet geometries. Modeling is performed to simulate behavior during a period when conditions are isothermal. It is determined that mean hydraulic residence time is 3–4?days; approximately half of what would be expected assuming strictly plug flow. The presence of a primary flow path, large scale eddies and stagnation zones contribute to the faster travel times. Reductions in inflow rates produce increased residence times and significant changes in flow patterns.     

川中—川西地区灯影组沉积层序特征及其对天然气成藏的控制作用

近期在四川盆地川中安岳地区震旦系灯影组发现了大气藏,持续深化优质储层展布规律、源储配置关系等地质认识,对拓展该区的油气勘探工作具有重要意义。为此,对川中—川西地区灯影组层序格架特征、沉积充填演化特征进行了研究,探讨了沉积过程对储层发育和分布、源储配置关系等的控制作用。结果表明:(1)德阳—安岳古裂陷总体上呈北西向展布,具有北宽陡、南窄缓的形态特征,且存在灯二期、灯四期2个裂陷边界,其中灯二期裂陷在德阳—内江一带呈"U"形展布;(2)灯影组可划分为4个Ⅲ级层序(SQ1~SQ4),SQ3时期,川中高石梯—磨溪地区可识别出完整的海进超覆和海退进积沉积反射结构,发育灯四段早—中期台缘带;(3)古裂陷在震旦系沉积之前就已有雏形,前震旦裂谷的继承性活动影响了震旦系的沉积充填及岩相展布;(4)SQ2、SQ4时期分别形成的灯二、灯四段裂陷边缘以及SQ3时期形成的灯四段早期台缘带是优质储层的有利分布区带;(5)环古裂陷下寒武统烃源区的灯二、灯四段边缘均具有侧接式源储配置关系,古裂陷东侧向川西北延伸的边缘带具有较好的天然气成藏潜力。     

胜北洼陷胜北构造带白垩系连木沁组沉积体系分布与岩性油气藏勘探

吐哈盆地胜北洼陷胜北构造带白垩系连木沁组属于典型的北物源扇三角洲前缘沉积体系,其砂体埋藏深度较浅,储层物性较好,向北上倾尖灭型岩性圈闭发育。根据胜北洼中隆良好的古构造背景,结合胜北3、4号南北向平移断层沟通中、下侏罗统水西沟群煤系地层和中侏罗统七克台组湖相泥岩烃源岩系等情况,认为胜北洼陷白垩系是浅层次生岩性油气藏勘探的有利地区。     

Reducing Numerical Diffusion Effects with Pycnocline Filter

Numerical or artificial diffusion is the unintentional smoothing of gradients associated with the discretization of the transport equations. In lakes and reservoirs where through-flow is small, the effects of numerical diffusion of mass are cumulative, leading to a progressive weakening of vertical density stratification. This density field misrepresentation precludes accurate, long-term, three-dimensional (3D), hydrodynamic simulations on fixed grids in closed basins with an active thermocline. An ad hoc technique to limit the destratifying effects of numerical diffusion of mass is presented and tested for a 3D, hydrostatic, Z-coordinate numerical model. The technique quantifies the domain-integrated numerical diffusion by assessing the change in the background potential energy Eb. At each time step, the change in Eb associated with numerical diffusion is calculated, then removed using a sharpening filter applied to each water column. In idealized test cases, the filtering technique is effective in maintaining density stratification over one year while undergoing periodic, large-amplitude forcing by internal waves. Forty-day simulations of Lake Kinneret compared to field measurements demonstrate improved representation of density stratification using the filtering technique.     

Extended-Period Analysis with a Transient Model

To design and operate a distribution system, one must understand how it will perform when subjected to external hydraulic loads and demands. This paper presents a hybrid model that efficiently tracks the full range of hydraulic conditions, from steady state to waterhammer, in a system over an extended period by coupling a transient simulator with a reservoir routing scheme. The model’s procedure consists of running waterhammer simulations at the start and end of an extended time step to track the rate of filling of a system’s reservoirs and then using this information to update reservoir levels at the end of the time step. Beyond conventional level-of-service and capacity-assessment applications, the hybrid model can help the engineer link system unsteadiness to its associated costs in terms of design and operation. Extended period and worst-case simulations presented in a case study suggest that the hybrid model has a high routing accuracy and can be used effectively to identify the critical state which will produce the most severe transients in a system.     

川南碳酸盐岩缝洞中隐蔽性天然气储量早期预测——“排水找气”井储量早期估算探讨

关于封闭性碳酸盐岩缝洞气藏天然气储量计算，已有公认的经典计算公式，而探讨缝洞性碳酸盐岩产水圈闭中隐蔽性天然气储量的预测和计算，尚属近年提出的新课题。根据物质平衡原理，推导了这类隐蔽性天然气储量计算公式，并提出“折算气量”新概念，建立气水同产井Ｐ／Ｚ—∑Ｇｐ关系压降图。运用该压降图，也可早期预测产水井中隐蔽性天然气储量。通过Ｈ１６井储量计算实例，得到了证实。     

表面活性剂降压增注技术现场应用效果分析

为了改善江汉油田低渗透油藏的注水开发效果,2006-2007年进行了表面活性剂的单井降压增注试验。通过室内研究筛选,确定了现场试验用药荆为综合性能较好的JT202。现场应用后,配合酸增作业挤入表面活性剂段塞8口井,有效6口,措施有效率75％,日增注水量50m3,平均有效期235天,有两个井组对应油井明显见效。点滴注入3口井,其中1口井见效明显。     

安塞油田坪北区低渗透油藏复合解堵技术研究

由于坪北油田储层物性差,孔隙度低,渗透率低,主要属于小孔细喉道,开采过程中很容易受到伤害,并造成油井近井地层的堵塞,从而使油井在措施后的较短时间内产量下滑。从地层堵塞的原因入手,综合考虑影响地层堵塞的各种因素采用合理的酸化解堵工艺,取得较好的现场应用效果。