Analysis Of Sequence Stratigraphy And Depositional Systems Of Fula Depression, Muglad Basin In Sudan

The objective zone of this paper is Fula depression that locates at the northeastern Muglad basin in Sudan. The target formation is from Abu Garbra formation to Darfur group. This paper focuses on the establishment of the synchronic stratigraphic framework, the effect of paleogeographic structure to the direction of paleocurrent and the distribution of sedimentary system in time and space, the type of sedimentary facies and it's evolution, the matching relations of generation, reservoir, seal rock, the prediction of favorable zone.We have integrated well-log data with seismic data to study the stratigraphic architecture that utilizes two sequence stratigraphic theories, Vail seismic sequence stratigraphy and Cross high resolution sequence stratigraphy. Basing on the analysis and correlation of the7 wells, 8 seismic sequence boundaries are obtained by logging-seismic correlation, based on seismogram synthesis. More over, they can be traced in the studying region. The synchronic sequence stratigraphic framework is established finally.Based on the synchronic seqence stratigraphic framework, through comprehensive investigation of the evaluation of seqence, the type of sedimentary facies and sedimentary system with it's area distribution, the domination of paleogeographic structure to paleocurrent and sedimentary system, draw a conclusion: The boundaries of the thickness of sequence was bounded by the boundary faults. The irregularity of sedimentary facies was dominated by base level rise to fall and accommodation. The types of sedimentary facies were mainly fan-shaped delta, delta, Binshore subaqueous fans, slump turbid fan, lake facies, fluvial facies. In the early term(SA,SB) and the late term(SE) of Abu Garbra, the fluvial facies and delta facies were deposited. At the developing stage of SC and SD, The sedimentary feature is dominated by faults, resulted in multi-provenance and multi-depositional systems. In the short axial direction, depression's steep side developed inherited inshore subaqueous fans. On the east terrace-fault slope of the depression,the sedimentary mode of fan-shaped delta-slump turbid fan -deep lake facies are developed. On the long axial direction of Fula depression, the southeastern groove was filled with a large scale delta which was the main sources, the other little delta limited by the 3 syndepositional fault was distributed down the slope edge of the northern sub-depression. This stage developed a favorable oil sources, reservoir and regional seal which formed the good matching relations of generation, reservoir and seal in the time-space zone. At the early phase of Darfur group, the lake faices was developed widely which formed fair seal.On the base of the study above, the SC, SD, SE of Abu Garbra formation were determined the target sequences of exploration. We predicated three favorable zones: the excellent play is at the downside of the east terrace-fault slope, the good play is distributed on the depression's steep, the common play around the edge of the slope of the depression.