基于油水相指数时变的相对渗透率计算方法

非稳态实验法获取的相对渗透率数据点主要集中在高含水饱和度处,水驱前缘数据点较少,直接应用到中轻质油田生产动态分析及数模拟合中易导致早期开发规律难以准确认识,不能完整反应整个开发历程。利用广适水驱曲线进行中低含水期含水饱和度计算,并将传统相对渗透率计算模型进行改进,创新性提出基于油水相指数时变的相对渗透率计算方法,实现低含水期相对渗透率数据加密。结果证明,该方法与稳态实验法测得数据吻合度较高,能够反应低含水期渗流规律,对于中轻质油田相对渗透率的获取具有借鉴意义。

油水相渗比值特征研究及新方法建立

油水相渗比值关系式是反映水驱油田渗流特征和建立水驱开发规律的基础。目前,油水相渗比值关系式种类较多,各种关系式之间相互关系复杂,给现场应用带来一些困惑。为此,编制了油水相渗比值关系式演化结构图。结构图上明显显示油水相渗比值关系式可划分为两大系列,即指数系列和方次系列。尤其是在方次系列中,随着油相指数与水相指数由相等变不等,再到油相指数、水相指数与含水饱和度相关,油水相渗比值关系式的拟合精度越来越高,其适应性越来越好;另外,从结构图中不仅可以发现已有油水相渗比值关系式研究过程中由于约束条件排列次序的不同而导致某些模型的遗漏,而且也可展示出现阶段该类技术的研究热点及方向。最后,利用大庆油田3类油水相渗数据对新增的油水相渗比值关系式进行了应用,结果显示,油相指数、水相指数与含水饱和度呈多项式关系时,多项式次数越高,拟合精度越高,误差越小。

一种用水驱曲线确定油田单井最佳提液时机的方法

本文在对油田单井提液理论和应用现状进行分析的基础上,研究并提出一种用于判断单井最佳提液时机的新方法。该方法首先对单井动态生产数据进行甲型处理,并通过甲型水驱曲线拟合相对渗透率曲线的油相、水相指数和水油流度比;再由此作出无因次采油、采液指数曲线图并进行最佳提液时机分析。所提出的理论和方法对油田开发把握单井提液措施的有利时机,提高作业成功率具有一定的实际应用价值。

水驱油田含水上升规律和递减规律研究μ

含水上升规律和递减规律是水驱油田的主要规律,但目前对于两者的内在联系及含水上升规律的主要影响因素还未认识清楚。根据相对渗透率曲线和分流量方程,从理论上揭示了水驱油田含水上升率的变化规律及其影响因素,同时研究了在定产液量的条件下含水上升率和递减率的关系。结果表明:含水上升率通常随可采储量采出程度先凹形上升后转凸形上升,上升到峰值后开始下降,先凸形下降后转凹形下降,转折点的含水上升率及对应的可采储量采出程度和含水率由水油流度比、水相指数和油相指数3个参数确定;在定产液量的条件下,含水上升率和递减率的变化规律一致。认清含水上升规律和递减规律,可以更准确地预测水驱油田的开发指标。

相渗曲线和水驱曲线与水驱储量的关系

根据相渗曲线和油水两相渗透率比值的表达式,导出了相渗曲线、水驱曲线和水驱储量的定量关系。结果表明,水驱地质储量大小与水相指数、油相指数之和呈正比,与甲型水驱曲线的斜率和驱油效率之积呈反比。这也解释了童宪章院士提出的"7.5法"不适用低渗油田的原因。

新型油水两相相渗关系式的建立及应用

在Willhite油水两相相渗关系式上,采用二项式表征油相指数与含水饱和度之间关系,出现了油相相渗曲线随含水饱和度的增大而不单调递减的现象,表明利用二项式表征油相指数与含水饱和度之间关系还存在不足,理论上也论证在油水两相流动区间可能存在突变。为了防止出现此类现象和方便油水相渗比值关系式待定参数得确定,文中提出了一种新的油水两相相渗关系式,即采用线性表征油相指数与含水饱和度之间关系,二项式表征水相指数与含水饱和度之间关系。这样处理,一方面可以确保油相相渗随含水饱和度单调递减,另一方面,水相相渗关系式可以描述弓背式水相渗流变化特征。最后,通过红台油田西山窑组油藏23区块的应用,新的油水两相相渗关系式及其油水相渗比值关系式拟合精度高、效果好,为进一步深化水驱油特征研究奠定了可靠的数理分析基础,值得其他油田借鉴。

Phenotypic correlations of somatic and gonad traits of sea urchins Glyptocidaris crenularis in two sampled periods:first insight into its breeding and aquaculture

Prior knowledge of the correlations among commercially important traits in Glyptocidaris crenularis can be used to guide development of breeding and aquaculture programs for this species.We evaluated the phenotypic correlations between somatic and gonadal traits in G.crenularis during two sample periods(October 2010 and April 2011).The coeffi cients of variation(CV%)for body weight(BW),redness(a*),yellowness(b*),gonad wet weight(GW),and gonad index(GI)were>20% in both periods,while those of other traits were very low.GW was signifi cantly correlated with somatic traits(diameter,height,and body weight)in both periods,although the correlation coeffi cients ranged from 0.473 to 0.636(P<0.01).Gonad moisture content(GC),a*,and lightness(L*)were not signifi cantly correlated with somatic traits(P>0.05).The color trait b* was negatively correlated with somatic traits(test diameter,test height,and body weight)during the period when the gonads were well developed(April 2011,P<0.05).We observed little difference in the nature of the phenotypic correlations between the two sample periods.The high variation in the somatic and gonad weight traits in G.crenularis suggests there is considerable potential for selective breeding.However,our results suggest that gonad quality traits cannot be selected indirectly by selecting for body weight.Our study provides an insight into the method for improving the breeding and aquaculture of G.crenulari.

Variation of Thornthwaite Moisture Index in Hengduan Mountains, China

The Thornthwaite moisture index, an index of the supply of water （precipitation） in an area relative to the climatic demand for water （potential evapotranspiration）, was used to examine the spatial and temporal variation of drought and to verify the influence of environmental factors on the drought in the Hengduan Mountains, China. Results indicate that the Thornthwaite moisture index in the Hengduan Mountains had been increasing since 1960 with a rate of 0.1938/yr. Annual Thomthwaite moisture index in Hengduan Mountains was between -97.47 and 67.43 and the spatial heterogeneity was obvious in different seasons. Thomthwaite moisture index was high in the north and low in the south, and the monsoon rainfall had a significant impact on its spatial distribution. The tendency rate of Thomthwaite moisture index variation varied in different seasons, and the increasing trends in spring were greater than that in summer and autumn. However, the Thomthwaite moisture index decreased in winter. Thomthwaite moisture index increased greatly in the north and there was a small growth in the south of Hengduan Mountains. The increase of precipitation and decrease of evaporation lead to the increase of Thomthwaite moisture index. Thornthwaite moisture index has strong correlation with vegetation coverage. It can be seen that the correlation between Normalized Difference Vegetation Index （NDVI） and Thomthwaite moisture index was positive in spring and summer, but negative in autumn and winter. Correlation between Thornthwaite moisture index and relative soil relative moisture content was positive in spring, summer and autumn, but negative in winter. The typical mountainous terrain affect the distribu- tion of temperature, precipitation, wind speed and other meteorological factors in this region, and then affect the spatial distribution of Thomthwaite moisture index. The unique ridge-gorge terrain caused the continuity of water-heat distribution from the north to south, and the water-heat was stronger than that from the east to west part, and thus determined the spatial distribution of Thornthwaite mois- ture index. The drought in the Hengduan Mountains area is mainly due to the unstable South Asian monsoon rainfall time.

Projections of the 21st Century Changjiang-Huaihe River Basin Extreme Precipitation Events

Based on the 1961-1990 observed daily precipitation in the Changjiang-Huaihe River Basin, the NCEP/NCAR reanalysis data, and the HadCM3 model data for IPCC SRES A1B climate projections, the simulation capabilities of the BP-CCA downscaling approach for extreme precipitation indices of the current climate are assessed by applying canonical correlation analysis (CCA). In addition, future extreme precipitation indices in the middle and late 21st century are projected. The results show that simulation capability of the HadCM3 for regional climate characteristics can be effectively improved by the downscaling approach, with 30%-100% reduction of the relative errors of the climatological mean state of extreme precipitation indices. However, the downscaling results still show wetter winter and dryer summer than the observation. Under the SRES A1B emission scenario, frequency and intensity of extreme precipitation events are projected to increase, and the estimated increasing rate is higher for extreme precipitation indices than for mean precipitation index; and in summer than in winter. Extreme precipitations in the middle and late 21st century are expected to increase by 14% and 25% respectively in winter, and by 24% and 32% respectively in summer.

常规砂岩油藏无水采油期采出程度计算新方法

基于不稳定渗流理论,建立水驱砂岩油藏渗流数学模型,用有限差分方法对其求解.分析了水油流度比、水相指数、油相指数、束缚水饱和度、残余油饱和度五个因素对无水采油期采出程度的影响,结果表明:无水采油期采出程度与水油流度比呈幂函数关系,与水相指数、油相指数、束缚水饱和度、残余油饱和度均呈线性关系.采用SPSS多元回归方法,得出五因素影响的理论无水采油期采出程度计算公式.公式将理论无水采油期采出程度与水油流度比、油相指数、水相指数、束缚水饱和度、残余油饱和度关联起来,为开发指标预测过程中确定见水节点提供了可靠的依据.