Optimization of Injection Parameters for Profile Control and Flooding in an Oilfield during High Water Cut Period

In order to improve the effect of water control and oil stabilization during high water cut period, a mathematical model of five point method well group was established with the high water cut well group of an Oilfield as the target area, the variation law of water cut and recovery factor of different injection parameters was analyzed, and the optimization research of injection parameters of polymer enhanced foam flooding was carried out. The results show that the higher the injection rate, the lower the water content curve, and the higher the oil recovery rate. As the foam defoamed when encountering oil, when the injection time was earlier than 80% of water cut, the later the injection time was, the better the oil displacement effect would be. When the injection time was later than 80% of water cut, the later the injection time was, the worse the oil displacement effect would be. The larger the injection volume, the lower the water content curve and the higher the recovery rate. After the injection volume exceeded 0.2 PV, the amplitude of changes in water content and recovery rate slowed down. The optimal injection parameters of profile control agent for high water content well group in Oilfield A were: injection rate of 15 m3/d, injection timing of 80% water content, and injection volume of 0.2 PV.

Application of New Water Flooding Characteristic Curve in the High Water-Cut Stage of an Oilfield

The oil production predicted by means of the conventional water-drive characteristic curve is typically affected by large deviations with respect to the actual value when the so-called high water-cut stage is entered.In order to solve this problem,a new characteristic relationship between the relative permeability ratio and the average water saturation is proposed.By comparing the outcomes of different matching methods,it is verified that it can well reflect the variation characteristics of the relative permeability ratio curve.Combining the new formula with a reservoir engineering method,two new formulas are derived for the water flooding characteristic curve in the high water-cut stage.Their practicability is verified by using the production data of Mawangmiao and Xijiakou blocks.The results show that the error between the predicted cumulative oil production and production data of the two new water drive characteristic curves is less than the error between the B-type water drive characteristic curve and the other two water drive characteristic curves.It is concluded that the two new characteristic curves can be used to estimate more accurately the recoverable reserves,the final recovery and to estimate the effects of water flooding.

A Method for Calculating Oil Field Relative Permeability Curve by Using Water Drive Characteristic Curve in High Water Cut Stage

With the production of strong bottom water reservoir, it will soon enter the ultra-high water cut stage. After entering the ultra-high water cut period, the main means of stable production is liquid extraction. Large liquid volume has a certain impact on the physical property distribution and fluid seepage law of the oilfield. The relative permeability curve measured according to the industry standard is not used for the prediction of development indicators and the understanding of the dynamic law of the oilfield. In order to understand the characteristics of water drive law in high water cut stage of water drive oilfield, starting from the water drive characteristic curve in high water cut stage, the method for calculating the relative permeability curve is deduced. Through numerical simulation verification and fitting the actual production data, it is confirmed that the obtained relative permeability curve is in line with the reality of the oilfield, It can provide some guiding significance for understanding the production law and water drive law of strong bottom water reservoir in ultra-high water cut stage.

Correct understanding and application of waterflooding characteristic curves

Through reviewing the generation process and essential characteristics of waterflooding curves, the essence and characteristics of Zhang Jinqing waterflooding curve and Yu Qitai waterflooding curve recommended in Chinese Petroleum Industry Standard 'Calculation methods for Recoverable Oil Reserves(SY/T5367—1998)' were discussed, and some technical issues related to the curves were examined in-depth. We found that:(1) All the waterflooding curves are based on empirical formulas derived from oilfield production experience and statistics methods, and can characterize oil displacement features by water quite well.(2) A new waterflooding curve can be derived by combining waterflooding parameters and using different mathematical calculations as long as the parameter combinations and mathematical operation meet a linear relationship, so proposing new waterflooding curves by changing the combination mode has no practical significance anymore.(3) The upwarp of waterflooding curve in the extremely high water cut stage is because the mobility ratio curve has an inflection point with the rapid rise of water cut after reaching a certain value, and the later rapid rise of mobility ratio changes the original two-phase flow dynamics.(4) After entering into water cut stage, all the waterflooding curves with linear relationship can be used to make prediction, even curves with inflection points, as long as they have a straight section above the inflection point.(5) Actual data of waterflooding oilfields has proved that Type A, Zhang Jinqing and Yu Qitai waterflooding curves all can predict accurately oil recoverable reserves in extremely high water cut stage and can be promoted.

基于投影寻踪模型的特高含水油藏剩余油可采潜力评价方法

影响特高含水油藏剩余油可采潜力的因素极其复杂,且各因素的影响程度差异明显,常规方法多以剩余油饱和度或剩余油储量丰度等单一指标评价剩余油潜力,难以有效指导特高含水油藏剩余油挖潜。在充分考虑特高含水油藏剩余油可采潜力影响因素的基础上,综合表征储层非均质性、剩余油可采储量规模、水淹状况以及油水分流能力的差异,构建了特高含水油藏剩余油可采潜力量化评价指标体系,并考虑不同指标对剩余油可采潜力控制程度的差异,将加速遗传算法与投影寻踪模型相结合来确定各评价指标的客观权重,从而构建了剩余油可采潜力指数,形成特高含水油藏剩余油可采潜力量化评价新方法。以渤海Q油田南区主力产层NmIL砂体为例,开展特高含水油藏剩余油可采潜力量化评价,结果表明,新方法可综合表征不同区域位置的储层物性、可采储量丰度和油水分流能力对剩余油可采潜力的影响,实现了主力产层NmIL砂体剩余油可采潜力分布的差异化定量评价,优势可采潜力区域刻画明显,将其作为NmIL砂体下一步井网加密调整潜力区域,以精准指导加密水平井的部署,为特高含水油藏剩余油挖潜提供了一种全新的分析方法与思路。

极端耗水层带形成机制及流场调控增效模式——以陆相砂岩特高含水后期整装油田为例

以胜利油区陆相砂岩油藏整装油田为代表,主力单元进入特高含水后期(含水率大于95%),局部区域出现极端耗水现象,水油比急剧上升,注入水利用率大幅下降,吨油操作成本成倍增加,经济效益变差,但油藏中还有60%左右剩余地质储量。注入水沿着极端耗水层带窜流是制约陆相砂岩整装油田特高含水后期效益开发的关键问题。以提高特高含水老油田开发效益为目标,明晰了极端耗水层带形成机制及调控机理,建立了基于老井的变流线调控极端耗水层带扩波及方法,形成特高含水后期油藏精准描述及调控极端耗水层带扩波及的效益开发技术体系。通过应用流场调控技术,使传统认为含水率98%近废弃油藏开展示范应用,基于极端耗水层带流场调控经济寿命期延长10a以上,产油量大幅增加,含水率下降,吨油操作成本下降,实现了特高含水后期老油田低成本开发。

海上高含水油井分段开采的选井方法应用研究

海上边底水油藏一旦见水会迅速进入高含水阶段,而分段开采可以达到抑制高含水和延长油井寿命的目的。因此,可利用分段开采机理模型对含水上升影响因素进行敏感性分析,研究高含水油井分段开采的选井方法依据,并利用数值模拟方法进行验证。结果表明:1)底水油藏水平井含水上升影响因素敏感性大小排序为黏度>高低渗级差>高渗条带比例>最大产液>高渗段渗透率。2)根据生产动态、水平段地质资料及邻井资料将海上底水油藏高含水水平井见水模式分为线性见水全面水淹、点状见水局部水淹和多点见水全面水淹,其中点状见水局部水淹模式可进行分段开采。以典型井A1为例,利用所建选井方法流程判断含水率曲线为线状见水特征,开井含水高,水平段渗透率分段特征明显,Ⅲ-1小层水淹程度较高,A1井跟部水淹严重,且由于第1套夹层遮挡,A1井趾部水淹程度较低,为点状见水模式局部水淹,符合分段开采特征。3)针对点状见水局部水淹水平井,采用分段开采进行稳油控水,利用数值模拟方法模拟预测,分段开采方案开发较不分段方案产油量和采收率得到显著提升,验证了选井方法及分段开采的适用性。提出的选井方法流程可为现场水平井分段开采选井研究提供方法依据。

海上油田“双高”阶段低效井综合治理研究

X油田是渤海典型的化学驱结束后续水驱油田,目前处于高含水及高采出程度的“双高”阶段,为解决开发生产过程中低产低效井逐渐增多且治理难度逐渐增加的问题,对油田储层沉积微相、地层物性参数、剩余油挖潜历程、开发方式转变、注采井网调整、增产措施影响等因素开展研究,分析低效井成因主要包括储层条件导致含水突升、井网不完善导致能量下降、过筛管压裂后采油井出砂等。针对不同成因低效井开展了分类治理研究,提出了区域流场调整、分层系开发、防砂筛管补贴等治理措施。20202021年矿场实践表明,对X油田12口低效井实施针对性的治理措施,单井平均高峰日增油达18 m^(3),预测治理有效期内将累增油21×10^(4)m^(3),该油田的低效井治理技术使油藏生产能力得到有效释放,为同类海上油田低效井治理提供了参考和借鉴。

复杂断块油藏高含水期剩余油分布规律研究

对于复杂断块油藏注水开发后期,剩余油分布规律刻画难度大,如何寻找剩余油甜点区成为提高水驱采收率关键。以H区块为例,在分析不同韵律性储层水淹特征基础上,开展剩余油分布特征研究,剩余油主要分布在生产井间、断层附近剩余油富集以及正韵律和渗透率极差小的反韵律厚油层顶部,并对不同类型剩余油制定合理的挖潜对策,包括实施加密井、老井侧钻及厚层顶部部署水平井等,现场部署实施各类井23口,日注水量增加440方,日产油量最高增加170t,采油速度提高0.28%,阶段累增油5.7万t,预计可提高水驱采收率5%,实现水驱控制储量有效动用。

石油地质工程中改善高含水期油田注水开发的措施

随着油田开发程度不断加剧,许多油田进入高含水期,对注水开发的效果提出了新的挑战。基于此,本文首先介绍了高含水期的概念及注水开发作为维持和提高油田产量的重要手段,随后详细分析了高含水期油田注水开发面临的主要挑战,最后提出了改善高含水期油田注水开发的具体措施,包括优化注水策略以减少水窜、加强水质管理与设备保护、提高能量效率与经济效益等方面的方法,希望为高含水期油田注水开发提供相关参考。

基于动态反演的“双高”油田驱油效率研究及挖潜实践

“双高”开发阶段油田水淹程度强,剩余油呈现整体分散、局部富集的分布特点,开展剩余油潜力精准评价对该阶段调整挖潜意义重大。以矿场实际生产数据为基础,在极限驱油效率室内试验认识的基础上,综合考虑矿场典型井网模式、水淹厚度、采出程度和含水率等因素,建立矿场级别下极限驱油效率动态反演数学模型,定量计算典型井网模式极限驱油效率。研究结果表明:1)原油黏度不同,驱油效率有差异,原油黏度为50 mPa·s时,驱油效率可达68%,原油黏度为300 mPa·s时,驱油效率可达62%;2)井网模式不同,驱油效率变化规律差异较大,结合SZ油田开发实际,定向井网极限驱油效率可达48%,水平井-定向井联合井网驱油效率可达61%~68%。SZ油田驱油效率仍有大幅提高空间,后续可通过调整井网进一步提高驱油效率。该研究成果考虑黏度差异的影响,定量评价高含水期油田井网调整对提高驱油效率的影响,为SZ油田潜力评价提供了指导,同时也为其他相同开发阶段油田提供借鉴。

XB油田特高含水期油井单管深埋冷输边界条件研究与应用

为了简化集输工艺和降低运行成本,对特高含水期油井单管深埋冷输边界条件进行研究,通过建立单管深埋冷输工艺模型,明确了单管深埋冷输工艺边界条件的计算方法,该方法可指导单管深埋冷输的应用范围。并在XB油田31口采油井开展了现场试验,结果表明,单管深埋冷输工艺适合于现场应用,应用后可有效节约电能及天然气消耗,年节电量11.12×10^(4)kWh,年节气量24.40×10^(4)m^(3),年节约管道维护费用49.6万元,可促进油田绿色低碳高效发展。

An effective method to predict oil recovery in high water cut stage

The water flooding characteristic curve method based on the traditional regression equation between the oil and water phase permeability ratio and the water saturation is inappropriate to predict the oil recovery in the high water cut stage. Hence, a new water flooding characteristic curve equation adapted to the high water cut stage is proposed to predict the oil recovery. The water drive phase permeability experiments show that the curve of the oil and water phase permeability ratio vs. the water saturation, in the semi-logarithmic coordinates, has a significantly lower bend after entering the high water cut stage, so the water flooding characteristic curve method based on the traditional regression equation between the oil and water phase permeability ratio and the water saturation is inappropriate to predict the oil recovery in the high water cut stage; therefore, a new water flooding characteristic curve equation based on a better relationship between ln（kro/k,.~） and S~ is urgently desirable to be established to effectively and reliably predict the oil recovery of a water drive reservoir adapted to a high water cut stage. In this paper, by carrying out the water drive phase permeability experiments, a new mathematical model between the oil and water phase permeability ratio and the water saturation is established, with the regression analysis method and an integration of the established model, the water flooding characteristic curve equation adapted to a high water cut stage is obtained. Using the new water flooding characteristic curve to predict the oil recovery of the GD3-block of the SL oilfield and the J09-block of the DG oil field in China, results with high predicted accuracy are obtained.

基于动态渗流阻力的注水调整方法

特高含水后期储集层油水两相渗流能力差异大,储集层动态非均质性强,以渗透率等静态参数作为主要指标的注水井层段细分方法和以经验分析为主的层段配水方法,难以满足多层砂岩油藏精准开发的需求。通过理论分析、物理模拟及数值模拟,深化了对特高含水后期油田渗流特征认识,构建油藏小层渗流阻力计算模型,以单井渗流阻力变异系数最小为目标,建立近阻注水井层段优化组合方法;构建层段剩余储量系数、合理注采比系数、相对注水效率系数及含水率上升速度系数,形成特高含水后期层段注水定量调整方法,解决了多井、多层、复杂注采关系条件下定量注水的难题。在典型区块应用,试验237井次,初期含水率下降0.14%,增油控水效果较好。

不同注采方式下层间非均质储层微观剩余油动用状况

特高含水期强非均质性油藏注水开发一直是油藏工程中重点研究的问题之一,而研究该问题的核心是明晰剩余油的分布、类型及启动方式。为了明确不同注采方式条件下微观剩余油的赋存状态,利用微流控驱替实验,针对强非均质性储层,对不同注采方式下微观剩余油进行动用状况定量化研究。储层中微观剩余油的主要分布类型以簇状流为主,柱状流和多孔流次之,滴状流基本没有赋存;基于微观剩余油定量分析,明确了不同注采方式对特高含水期强非均质性储层剩余油采出程度的提高效果,其中轮注轮采对该体系提升最大,分注轮采次之,轮注合采最差;并进一步研究了不同类型的注采方式在微观驱替时主要作用的剩余油类型及其作用机理。研究成果为该类型储层注水开发过程中注采方式的选择提供了理论依据。

高含水期原油低温集输温度界限模型研究

随着油田进入高含水期,原油流动特性发生了较大变化,而传统的集输工艺流程能耗较高,为了降低集输能耗,急需对管道低温集输温度界限进行研究。因此,在华北油田测试区块建立了可视化试验装置,研究实际生产过程中高含水原油低温集输特性和温度界限。研究结果表明,随着集油管线温度的降低,存在3个压降变化的转折点,其中压降增加率突变点和压降峰值点所对应的特征温度可作为低温集输的温度界限,据此拟合得到了满足实际生产需求的黏壁温度回归模型。基于所得模型,针对不同工况下低温集输的温度界限进行了预测,并据此创建了低温集输可行性的图示判断工具。所得结果对高含水期油田实际生产中低温集输的可行性判断及其安全运行管理具有指导意义。

特高含水期油藏潜力区与开发对策耦合方法

针对高含水期油藏剩余油分布特征,以油藏工程理论为基础,考虑经济因素,建立了特高含水期油藏剩余可采储量丰度分区划分方法,得到了整个油藏的高潜力区域与低潜力区域。结合油藏渗流状况划分出了油藏的高速流动区域与低速流动区域。综合考虑2种分区结果,进一步确定了不同区域的开发对策。在实际区块的应用结果表明,综合考虑油藏的高潜力区域与低潜力区域和地层渗流的低速流动区域与高速流动区域,可以与开发对策进行有效耦合,对特高含水期油藏调整开发对策具有实际指导意义。

中高含水率期油藏薄互层状剩余油动用技术

受储层非均质性影响,注水开发油藏经过长期注水冲刷形成水流优势通道,导致油井过早水淹,但仍有大量剩余油呈薄互层状赋存。中高含水率期提高采收率的核心就是如何动用这部分剩余油,本文在立足单砂体剩余油精细刻画基础上,根据单砂体剩余油控制因素及分布特征,通过注采结构优化调整、微球调驱及气驱提高采收率技术,有效改善了驱替效果,增加了可采储量,预测提高采收率3.00%。

基于流线数值技术的特高含水后期油田改良模拟研究

大角度转流线是特高含水后期油田改善开发效果的重要手段之一。以TS8区块为研究对象,利用流线数值技术开展了特高含水后期油田大角度转流线的数值模拟研究,分析了目标区块大角度流线调整前后剩余油的分布特征,从流线、压力梯度、构造形态、储层相对渗流阻力(饱和度)差异、工作制度等角度总结了已实施矿场井不见效的原因,并在此基础上开展了对策研究。结果表明:TS8区块的剩余油以形成流线但未有效驱替类为主;压力梯度是影响大角度转流线效果的主控因素,且大角度转流线后压力梯度应为0.03~0.04 MPa/m。将研究成果进行了矿场应用,油田含水下降1.5%,预测15年能够实现增油10.23万t,有效改善了注转采井的开发效果。研究成果为特高含水后期油田进一步提高采收率提供了一定的技术支持。

基于多变量时间序列模型的高含水期产量预测方法

针对油田高含水期地质条件复杂、地层物性变化多样导致产量预测正确率低的问题,提出一种基于多变量时间序列模型即多变量长短期记忆神经网络(LSTM)的产量预测方法。在基于极限梯度提升算法(XGBoost)筛选产量主控因素的基础上,建立综合考虑产量与地质、开发等影响因素之间相关性特征,并兼顾产量自身的时序性变化特征的产量预测模型;实验选取中国某中高渗透砂岩区块油田生产历史数据进行高含水期产量预测模型的训练和测试,并与单变量长短时记忆模型以及其他全连接网络模型结果进行比较。结果表明:该方法具有较好的预测性能,新模型克服了传统全连接神经网络无法描述产量时序数据相关性,以及单变量LSTM无法表征高含水期产量变化受多因素影响的问题,有效地提高了油田高含水期产量预测的准确性。