海平面变化对海相临滨储层微观非均质性的控制作用——以塔里木盆地哈得4油田东河砂岩为例

The controlling effect of sea level changing on the microscopic heterogeneity of marine reservoir:Taking shoreface subfacies reservoir of Donghe sandstone in Hade 4oilfield as an example

储层微观非均质性控制了油藏内微观剩余油的分布,为探究储层微观非均质性成因,以哈得4油田东河砂岩段临滨亚相储层为例,利用岩心、测井及多种分析化验资料为基础,分析了准层序、准层序组及体系域内储层颗粒、填隙物及孔喉非均质性的变化特征,总结出不同级次的海平面相对变化对临滨亚相储层微观非均质的控制成因机理,认为由于不同级次海平面的相对升降,使临滨亚相沉积水动力发生变化、先期形成的临滨储层所处地表环境亦发生变化,从而对颗粒、填隙物及孔喉非均质特征产生影响.研究结果表明:准层序内单一临滨亚相储层颗粒非均质性向上变弱,粒度中值由0.12mm变为0.22mm、长石及岩屑体积百分比由18%变为9%,填隙物及孔喉非均质性向上减弱,其中填隙物体积百分比由11.0%变为2.7%、喉道半径由1.9μm变为3.6μm,使准层序内单一临滨亚相储层微观非均质总体表现为向上减弱的趋势;东河砂岩段下部退积式准层序组内部,单一临滨亚相储层微观非均质总体表现为向上增强的趋势,而上部进积式准层序组内单一临滨亚相储层微观非均质呈由强变弱的特征,进积式准层序组中粒度中值由0.15mm变为0.23mm、长石及岩屑体积百分比由18%变为11.5%、填隙物体积百分比由13.7%变为6.3%、喉道半径由1.6μm变为3.7μm;高位体系域内单一临滨储层微观非均质性表现为减弱的特征,不同层序单元内微观非均质性变化程度不同.针对碳氧同位素及储层薄片分析结果较好证实以上观点.

The microscopic heterogeneity of reservoir controls the distribution of microscopic remaining oil in the reservoir.To study the origin of micro heterogeneity in reservoirs,taking shoreface subfacies reservoir of Donghe sandstone in Hade 4Oilfield as an example,the analysis of reservoir particles,interstitial material and variation characteristics of pore throat heterogeneity within the parasequence,parasequence group and system were conducted based on core,logging data and laboratory analysis data.The controlling genetic mechanism of relative sea level with different orders on micro heterogeneity in single shoreface subfacies were summarized.It is considered that because of the relative sea level fluctuation in different orders,the sedimentary hydrodynamic of shoreface subfacies was changed,and the surface environment of the pre-formed shoreface reservoir was also changed,which had a great impact on the particles,interstitial material and pore throat heterogeneity characteristics.The results show that in the parasequence,the particles heterogeneity of single shoreface subfacies reservoir becomes weaker upward,the median grain size changes from 0.12to 0.22mm and the percentage of feldspar and debris changes from 18%to 9%.The interstitial material and pore throat heterogeneity becomes weaker upward,the volume fraction of the fillings changes from 11.0%to 2.7%,and the throat radius changes from 1.9to 3.6μm,which makes the microscopic heterogeneity of single shoreface subfacies reservoir weaker upward in an overall trend.Inside the retrogradational parasequence group in the lower part of the Donghe sandstone,the microscopic heterogeneity of single shoreface subfacies reservoir shows an enhanced upward trend.Inside the progressive parasequence group in the upper part of the Donghe sandstone,the microscopic heterogeneity of single shoreface subfacies reservoir changes from strong to weak.In the progressive parasequence group,the median grain size changes from 0.15to 0.23mm,the percentage of feldspar and debris changes from 18%to 11.5%,the volume fraction of the fillings changes from 13.7%to 6.3%,and the throat radius changes from 1.6to 3.7μm.In the highstand system track,the microscopic heterogeneity of single shoreface subfacies reservoir is weaker upward.The variation degree of microscopic heterogeneity in different sequence units is different.According to the analysis results of carbon and oxygen isotopes and reservoir thin sections,the above views were better confirmed.