Sinjar隆起西翼储层裂缝发育特征及形成机制

Characteristics and formation mechanism of reservoir fractures in the west tip of Sinjar uplift

裂缝发育程度是影响裂缝性油气藏产能的决定因素。为了更好地揭示裂缝性油藏的发育特征,根据三维地震资料解释成果结合FMI成像测井资料,利用构造要素相关性分析及构造解析方法,探讨了Sinjar隆起西部倾末端裂缝发育特征及形成机制。研究结果表明:Sinjar隆起西部裂缝发育特征在纵向上存在分层性,从深层向浅层裂缝走向呈现逆时针旋转的特征,认为裂缝的发育和早期张性大断裂在后期的走滑再活动有关。走滑断裂从深层到浅层逐渐偏离原断层走向,剪破裂方向从深层向浅层逐渐分叉,越往上破裂方向越远离主断层,同样影响了裂缝的走向。由于深层大断裂和浅层裂缝发育存在一定相关性,受深层断裂的影响,裂缝发育强度由Jaddala组向Chilou组逐渐变弱,而裂缝又是碳酸盐岩储集层的关键元素,因此深层走滑断裂带发育的区域是寻找优质储层的有力目标。

The development extent of fractures is a decisive factor that affects the productivity of a fractured reservoir. In order to better understand and reveal the development characteristic of a fractured reservoir, the characteristics and the formation mechanism of fractures in the west tip of Sinjar uplift are studied using the methods of structural analysis and correlation of structural elements based on 3D seismic and FMI data. The fractures are vertically stratified with anticlockwise-rotating strikes from lower to upper formations. The development of the fractures sees a close relationship with the reactivation of large faults developed in the underlying layers. The reactivated deep faults in the later stage are the strike-slip faults, and the strikes rotate anticlockwise while developing upward, which affeets the orientation of new fractures developed on the top layer of the strike-slip tauhs. Due to the importance of fractures to carbonate reservoirs, and the close relationship between the shallow fractures and the deep-burying strike-slip faults, the intensity of fi＇actures is decreasing upward from Jaddala formation to Chilou formation, and the areas with deep faults being developed shall be good prospecting places.