Sequence Stratigraphy Study And Reservoir Prediction For Palogue Oil Field, Sudan

Palogue is a giant oil field found in Sudan during the period of "Tenth Five-Year Plan"under the guide of CNPC's "Going-Out Strategy", which is still under the stage of construction atpresent. Results of regional research show that the reservoirs of Palogue belong to continental facesedimentary strata predominated by braided rivers. Due to the strong heterogeneity of reservoirdistributions in macro-scope and the complexity of rule of sand body distribution in plane, it isnecessary to apply the theory and technology of hi-resolution sequence stratigraphy, esp. the methodfor river face sequence division, to conduct a hi-frequency sequence stratigraphy study, so as tofurther definitude the sand body distribution rule, to a solid foundation for the development of thefield.By referring to the multi-stage inferior datum plane, applying the theory and method ofhi-resolution sequence stratigraphy, taking drilling, logging and 3D seismic data as the basis, thisthesis confirms that Groups Yabus and Samaa are two three-stage sequences in the same two-stagesequence, which can be further divided into three four-stage cycles and eight five-stage cyclesFive-stage cycles are corresponding to related reservoirs. Within equal-time framework and based onthe analysis of rock structure, core description, logging faces and seismic faces, the formation causetype of reservoir and sedimentary faces is made certain. What put forward in this dissertation is thetype of sedimentary faces of Samma—YabusIV belong to a braided river sediment on a delta plane,and Yabus I—III belong to a strip shape river face sediment on a fluvial plane under a draughtclimate. A source analysis is conducted based on a sand cut statistics for wells within the four-stagecycle and the plane distribution of sand cut, which shows that the source rack comes both fromnorthwest and northeast directions. The main controlling factors for sediment and sequenceformation are discussed, founding that the transition from the braided river delta plane sediment tothe fluvial river face sediment is influenced mainly by structure, faults and climate. The distributionrule of reservoir in the fifth-stage cycle is predicted through the combination of geological analysisand geophysical method, showing that the distribution rule of reservoir is consistent to the rule ofsedimentary face evolution and formation sequence. The physical properties of reservoirs arecontrolled by sedimentary faces. The properties of braided river sand bodies are the best, with strongcontinuity, corresponding more favorable reservoirs. However, the properties of out-flowing sandbodies are inferior, with not continuous distribution, and corresponding less favorable reservoirs.A method of comprehensive research with multi-discipline is adopted in this thesis. By taking aseries of theories as the guideline, covering sequence stratigraphy and reservoir geology, bycomprehensively utilizing such information as geology, seismic data, well logging data and welltesting data to the greatest extent, and by combining the overall study together with specificresearches on the Palogue Oilfield reservoir, a sequence stratigraphic framework has been set up forthe target formation of the area investigated, which discloses the distribution rule of sediment system,reservoir and physical property of the area. In this paper, a set of concepts, methods and technologiesare discussed on the application of high resolution sequence stratigraphy to continental faces braidedriver sediment stratum, which is of great practical significance, and enriches the theory of highresolution sequence stratigraphy.