阿尔及利亚Zarzaitine油田下泥盆统沉积特征及演化规律

阿尔及利亚Zarzaitine油田下泥盆统F4层油藏已开发了40多年，但对其储集层的沉积特征及分布却认识不清，严重制约了该油田剩余油挖潜和开发调整方案的整体部署。综合应用沉积岩石学、地质学等多学科理论，全面分析了F4层的岩石学性质、沉积构造特征、测井曲线特征、古生物特征等，认为F4层的沉积相为陆隆一半深海环境下重力流沉积的海底扇。工区内仅发育海底扇中扇亚相和下扇亚相，从中扇近端到远端、末端直到下扇亚相，重力流逐渐从碎屑流向颗粒流、液化流、低密度浊流演化，最终演化为牵引流。从下到上，F4层的沉积相平面分布从“中扇为主、下扇为辅”演化为“中扇发育、下扇消亡”，最终转变为“中扇缩小、下扇扩大”。分析认为海平面从下降到上升是该区沉积微相空间变化的主控因素。图4参18

Sedimentary characteristics and evolution of Lower Devonian in Zarzaitine Oilfield,Eastern Algeria

The petrologic characteristics, sedimentary structures, well log curves and paleontology of the Lower Devonian F4 reservoir in the Zarzaitine Oilfield of Algeria were analyzed from a multi-disciplinary aspect. It shows that the sedimentary facies are submarine fans deposited by gravity flow at the bathyal depth. The mid-fan and lower-fan sub-facies of submarine fans are developed. From the proximal to the mid, the distal of the mid-fan and to the lower-fan, gravity flow evolves gradually from debris flow to grain flow, liquefied flow, low density turbidity current and finally to traction current. The planar distribution features of the reservoir sedimentary facies are that the lower part consists of predominant mid-fans and subordinate lower-fans, the mid part comprises mid-fans without lower-fans, and the upper part comprises reducing midfans with lower-fans expanding. The sea level changing from fall to rise is the main controlling factor of the spatial shift of sedimentary micro-facies.