苏丹Muglad盆地6区基岩储层发育特征及其勘探意义

Development characteristics and exploration signifi cance of basement reservoirs in block-6 of the Muglad Basin,Sudan

在邻区多个盆地基岩潜山勘探陆续获得突破的背景下,苏丹Muglad盆地基岩勘探备受关注。基于盆地勘探实际,充分利用Muglad盆地6区钻井、测井、测试和三维地震等资料对基底岩性和储层发育特征进行研究,并分析其勘探意义。盆地基底岩石由长石、石英、角闪石和云母等矿物组成,其原岩属于长英质花岗岩或花岗闪长岩,并经历了不同程度区域变质或动力变质,属低级—中级变质程度的变质岩。研究区内基岩储层具有双层结构,浅层属风化淋滤带,中—深层以裂缝发育带为主。风化淋滤带主要发育在隆(凸)起表层,厚度较小,通常不足50m,以风化淋滤作用为主,多见岩石破碎和矿物溶蚀,孔洞发育;裂缝发育带厚度一般较大,但区域分布不均,在盆缘和坳—隆过渡带较发育,是盆地基底主要储层类型。富油气坳陷(或凹陷)边缘陡坡带、坳—隆过渡带等裂缝发育区应是未来基岩勘探的优先方向。

With the breakthroughs of the exploration of basement buried hill in several adjacent basins,the basement exploration in the Muglad Basin in Sudan has attracted a lot of attention.Based on the exploration practice of the basin,this paper makes full use of drilling,well logging,testing and 3D seismic data in block-6 of Muglad Basin to study the basement lithology and reservoir development characteristics,and analyzes its exploration signifi cance.The basement rock of the basin is composed of feldspar,quartz,hornblende,and mica.The protolith is felsic granite or granodiorite,which experienced regional metamorphism or dynamic metamorphism in different degrees,so that the basement rocks are metamorphic rocks of low to intermediate metamorphism.The basement reservoirs in the study area have double-layer structure.The shallow layer is weathering crust,and the middle-deep layer is mainly fracture zones.The weathering crusts are mainly developed in the surface of uplift(high),with small thickness,usually less than 50m.With weathering and leaching,there are broken rocks and dissolved minerals.The pores and cavities are developed.The fracture zone is generally thick,but the distribution is uneven.In the basin margin and the transition zone between depression and uplift,it is developed,and is the main reservoir type of the basin basement.The fracture development areas such as the steep-slope zones at the edge of petroleum-rich depression(or sag)and the depression-uplift transition zones should be the priority direction of basement exploration in the future.