Remaining Oil Distribution Law and Potential Tapping Strategy of Horizontal Well Pattern in Narrow Oil Rim Reservoir with Gas Cap and Edge Water

For thin oil rim reservoir with gas cap and edge water, it is helpful to improve the development effect to find out the distribution law of remaining oil in this kind of reservoirs. For this reason, taking the narrow oil rim reservoir with gas cap and edge water of Oilfield A in Bohai Sea as a case, the main controlling factors, including reservoir structure, fault, gas cap energy, edge water energy and well pattern, affecting the distribution of residual oil in this kind of reservoir were analyzed by using the data of core, logging, paleogeomorphology and production. Then, the distribution law of remaining oil was summarized. Generally, the remaining oil distribution is mainly potato-shaped or strip-shaped in plane. Vertically, it depends on the energy of gas cap and edge water. For the reservoir with big gas gap and weak edge water, the remaining oil mainly lies in the bottom of oil column. And for the reservoir with small gas gap and strong edge water, the remaining oil mainly locates at the top of oil column. Aiming at different distribution modes of remaining oil, the corresponding potential tapping strategies of horizontal wells are put forward: in the late stage of development, for the reservoir with big gas gap and weak edge water, the remaining oil concentrates at the bottom of the oil column, and the position of horizontal well should be placed at the lower 1/3 to the lower 1/5 of the oil column;for the reservoir with small gas cap and strong edge water, the remaining oil locates at the top of the oil column, and the position of horizontal well should be put at the upper 1/5 to the upper 1/3 of the oil column height, vertically. Based on the study on remaining oil of Oilfield A, a potential tapping strategy of well pattern thickening and vertical position optimization of horizontal well was proposed. This strategy guided the efficient implementation of the comprehensive adjustment plan of the oilfield. Moreover, 18 infill development wells were implemented in Oilfield A, and the average production of the infill wells is 2.1 times that of the surrounding old wells. It is estimated that the ultimate recovery factor of the oilfield will reach 33.9%, which is 2.3% higher than that before infilling wells. This study can be used for reference in the development of similar reservoirs.

Progress and prospects of EOR technology in deep,massive sandstone reservoirs with a strong bottom-water drive

The Triassic massive sandstone reservoir in the Tahe oilfield has a strong bottom-water drive and is characterized by great burial depth,high temperature and salinity,a thin pay zone,and strong heterogeneity.At present,the water-cut is high in each block within the reservoir;some wells are at an ultrahigh water-cut stage.A lack of effective measures to control water-cut rise and stabilize oil production have necessitated the application of enhanced oil recovery(EOR)technology.This paper investigates the development and technological advances for oil reservoirs with strong edge/bottom-water drive globally,and compares their application to reservoirs with characteristics similar to the Tahe oilfield.Among the technological advances,gas injection from the top and along the direction of structural dip has been used to optimize the flow field in a typical bottom-water drive reservoir.Bottom-water coning is restrained by gas injection-assisted water control.In addition,increasing the lateral driving pressure differential improves the plane sweep efficiency which enhances oil recovery in turn.Gas injection technology in combination with technological measures like channeling prevention and blocking,and water plugging and profile control,can achieve better results in reservoir development.Gas flooding tests in the Tahe oilfield are of great significance to identifying which EOR technology is the most effective and has the potential of large-scale application for improving development of deep reservoirs with a strong bottomwater drive.

A New Method for the Dynamic Reserves of Gas Condensate Reservoir Using Cyclic Gas Injection Based on the Effects of Reinjection Ratio and Water Influx

As we all know, cyclic gas injection is one of the most effective development methods to improve condensate oil recovery. When dealing with the calculation of the reserves, the injection-production differences and water influx create great influence on the accuracy. Based on the existing research, we proposed a new material balance equation which considered the differences of composition between produced and injected fluids and the effect of water influx, and a solution was provided in this paper. The results of the method are closer to the actual situation because they are built on the law of conservation of mass, and the using of curve fitting method can not only avoid the use of water influx coefficient but also obtain the water influx rate and reserves at the same time. The YH-23 gas condensate reservoir is taking as a typical subject to do the research, which has been exploited by cycle gas injection for 14 years. Three different methods are used to calculate the reserves, and the results show that the method proposed in this paper has minimum error of 2.96%.

边底水凝析气藏气井出水来源综合识别方法

边、底水凝析气藏在开发过程中易受地层水侵入,部分气井会由于边、底水侵入而高含水停产,但水侵过程往往需要较长的时间,因而不能将出水原因均归结为边、底水侵入。考虑边底水凝析气藏的反凝析特征、地层中的优势渗流通道以及井底附近的油、气、水三相流动,运用凝析水分析、生产动态分析、测井解释分析、井间优势渗流通道识别、出水层位判断和数值模拟论证方法综合判断凝析气井出水来源,以塔里木盆地塔河凝析气藏A区块2口采气井为例详细说明了识别过程。对单井出水来源的准确识别,有助于掌握地层水的运动规律,对边底水凝析气藏的治水、控水、稳产开发有重要意义。

中国海上气田开发与提高采收率技术

中国海上目前在生产气田共计有30个、气井总数为288口,主要分布在莺歌海盆地、琼东南盆地、珠江口盆地、东海陆架盆地和渤海湾盆地。海上气田的勘探成本、工程建造成本、钻完井和生产操作费用均较高,加之开发调整及生产措施实施难度大,因而陆上气田开发采用的相关方法和技术在海上推广应用便受到诸多限制。为了提高中国海上气田开发的效益,有必要归纳和总结我国海上气田在开发技术与提高天然气采收率技术方面的研究成果与实施经验。按照气藏特点,将中国目前的海上气田分为凝析气藏、低渗透气藏、边底水气藏、高温高压含酸气气藏、深水气藏等5种类型;在此基础上,对其地质特征、开发特点及存在的问题分别进行了探讨;进而结合典型案例对各类气藏的配套开发技术与提高天然气采收率技术及实施经验进行了总结;最后对中国海上天然气开发技术的发展方向及潜力给予了展望。

多层系边底水气藏生产动态特征及见水时间预测方法

针对多层系气田不同层之间压力系统、水体能量、储层物性不同而导致的气藏生产动态规律差异明显的现象,以Z气田为例,分析了气井生产过程中凝析油含量变化规律,明确了影响凝析油含量变化的主控因素。研制了气井出水类型判别图版,通过计算井底与井口2种条件下天然气饱和水量的差值,能够判别气井出水类型。采用现代产量递减分析方法确定地层压力变化规律,基于气藏物质平衡方法,计算不同时刻气井的水侵量和水侵替换系数,明确了气井3种见水模式。建立了考虑储层倾角的边水气藏见水时间解析预测方法,研制了不同储层倾角、日产气量情况下的见水时间预测图版,为Z气田未投产气藏以及同类型气藏的高效开发提供了技术支撑。

考虑反凝析的边水凝析气藏见水时间预测新方法

边水凝析气藏开发过程中,地层压力下降至露点压力后,凝析油析出。以往气井见水时间预测通常忽略了凝析油析出的影响,因此造成预测结果与实际结果有较大差异。为了更好地开发边水凝析气藏,准确预测见水时间,需考虑凝析油影响。基于多孔介质流体质点渗流规律,考虑反凝析油的影响,推导了近似直线供给边界的边水凝析气藏见水时间预测新公式。实例应用表明对边水凝析气藏见水时间预测时必须考虑凝析油的影响。预测新公式为深入研究边水推进机理,控制见水时间提供了理论依据,对边水凝析气藏生产管理具有重要的指导意义。

牙哈凝析气田边水推进判断方法研究

牙哈凝析气田是目前国内已投入开发的规模最大的,具有边水的整装凝析气田。对于水侵凝析气藏,掌握了水侵特征才能有效改善气藏的开发条件。在现场应用中经常采用试井解释的方法研究边水推进的情况。但井底相态变化会影响到试井特征曲线,从而使边水推进的情况不易判断。文章使用现代试井解释方法,应用KAPPA公司的Saphir试井解释软件对牙哈凝析气田3口生产井历次压力恢复试井先进行了试井解释,然后建立三维数值模型,将试井解释成果与数值模拟研究成果相结合,综合判定牙哈凝析气田边水推进的情况。这对正确认识凝析气藏开发动态及水侵特征,加强动态监测技术研究,对凝析气藏进行有效开发起着重要的指导作用。

边水凝析气藏型储气库多周期注采水侵量计算模型

针对边水凝析气藏型储气库相态变化复杂而导致水侵量计算较为困难的问题,基于物质守恒原理,鉴于储气库注采气体差异,考虑注入烃类气体与凝析气混合、凝析气反凝析、边水侵入和岩石束缚水压缩性等因素,推导边水凝析气藏型储气库物质平衡通式,建立水侵量和相关参数计算方法,结合中国某边水凝析气藏改建的储气库运行动态数据,计算和评价储气库多周期注采水侵量变化。结果表明:水侵量的计算结果符合储气库注采地层压力的升降特征;随着储气库多周期扩容和库存量增加,总体水侵量逐渐减小;与考虑反凝析因素相比,不考虑反凝析因素计算的水侵量值偏大;由于注入的烃类气体对凝析气的抽提作用,反凝析对水侵量的影响程度逐渐减弱;新模型计算的水侵量与数值模拟方法结果吻合较好。

边水凝析气藏高产井见水时间预测新模型

凝析气藏见水时间预测模型考虑反凝析作用,但忽略了高产井近井区域非达西效应的影响,造成见水时间预测产生偏差。针对该问题,运用气水两相渗流力学理论,综合考虑气相非达西效应和反凝析作用的影响,得到边水凝析气藏高产井见水时间预测新模型。研究结果表明:预测边水凝析气藏高产井见水时间需考虑气相非达西效应和反凝析作用的影响,两者均会导致气体流速增大,见水时间变早。将新模型应用于A气田S45、AT11-6H、AT11-4井和AT11-2井,其计算结果相对误差小于8%,相比常用计算模型,精度提高了18.10%~39.34%,计算结果与现场实际数据吻合度高。研究成果对深入分析反凝析作用和气相非达西效应对凝析气藏边水推进的影响,预测边水凝析气藏的见水时间有重要的指导意义。

边底水凝析气藏气井产出水来源判断方法

气井生产过程中，影响气井产量的主要因素是井筒积液，而对于边底水凝析气藏这种矛盾表现得更为突出，因此正确预测和及时有效识别出水来源，对提高或稳定气井产量以及改善气藏开发效果有重要的意义。以A凝析气藏为研究背景，通过产出气中凝析水含量计算，生产井产气量、产水量、水气比等生产特征参数变化来确定气井具体的产水类型及井筒积液的来水特征，从而正确认识储层构造特征和气水分布关系，以利采取有效的控水措施。

考虑反凝析影响的边水凝析气藏见水时间预测模型

凝析气藏开发过程中,当井底流压低于露点压力时,近井地带凝析油析出,形成凝析油聚集区。目前,见水时间预测模型通常不考虑凝析油聚集区凝析油饱和度对气水渗流能力的影响,预测结果有一定偏差。为了更准确地预测凝析气藏的见水时间,基于多孔介质流体质点渗流规律,提出以反凝析区域与未反凝析区域气水流度比之比来反映反凝析区域水相相渗变化,从而推导了新的边水凝析气藏见水时间预测模型。实例研究发现,预测凝析气藏见水时间必须要考虑反凝析区域和未反凝析区域气水渗流能力的不同,反凝析越严重,反凝析区域气水流度比越大,见水时间越早。新模型更深入地分析了反凝析对边水凝析气藏边水推进的影响,对边水凝析气藏的见水预测具有重要指导意义。

海上带凝析气顶的边底水油藏开发策略——以我国海上X油田H油藏开发为例

带凝析气顶的边底水油藏由于油气水关系复杂，开采难度大，容易出现油、气、水互窜，导致凝析油和原油的损失。对于这种复杂的油藏，不同的开采技术政策对油气采收率影响较大。以我国东部海域X油田 H油藏开发为例，在对气顶底水油藏的开发机理研究的基础上，结合海上油气田开发特点，提出带凝析气顶的边底水油藏开发策略：利用天然能量，先期以采油为主，后期兼顾采气；采用水平井开发，生产压差控制在1～1.5M Pa ，纯油区开采4～5a后封水平段油层，开采上部顶气。

东海平湖油气田中高渗凝析气藏开发效果分析

东海平湖油气田放鹤亭始新统平湖组气藏,属中高渗砂岩中低凝析油含量凝析气藏,1999年3月投入生产,采用衰竭式开采,至今已有8个年头,目前仍处于开发稳产阶段,日生产天然气量在140×104m3左右。通过对平湖油气田凝析气藏开发生产状况跟踪研究发现,其采气速度高、主力气藏气井无水采气期普遍较长、气油比随着压力下降而上升、凝析油含量随着压力下降而下降、天然气采收率将优于开发方案设计值,同时也发现,防止气井出水、出砂是中高渗凝析气藏开发中应予以高度重视的问题。平湖油气田凝析气藏开发,在技术上和经济上都取得了较好的效果,可以借鉴于类似凝析气田的开发实践中。

边水凝析气藏型储气库多周期工作气量计算方法

含有边水的凝析气藏型储气库运行投产后,在多周期扩容过程中,由于季节调峰需求,储气库的采气阶段并不能完全按照上下限压力运行,并且由于气水关系复杂和凝析气相态变化,导致储气库工作气量参数计算较为困难。基于物质平衡原理,推导考虑边水侵入、凝析气相态变化及岩石压缩性的边水凝析气藏型储气库物质平衡方程,通过计算各注采周期内储气库可动用的含气孔隙体积,建立了边水凝析气藏型储气库多周期工作气量的计算方法,结合国内某地下储气库进行了实例验证,结果表明模型计算工作气量值与实际工作气量吻合较好。该方法提高了储气库工作气量的计算准确度,对储气库多周期盘库和高效运行管理提供了技术支撑。