Print this pageGulf of Suez Petroleum System Charge: Volumes and Distribution of Light and Heavy Oil and the Controlling Factors
KHAVARI KHORASANI, GANJAVAR, and JOHN DOLSON
A major risk associated with oil exploration in carbonate-sourced petroleum systems is the oil quality. The discovered fluids show large variations in API and sulfur content. We will discuss the results of a multidisciplinary study in the Gulf-of-Suez, which addresses the factors controlling the distribution of heavy and light oils in this area. The main conclusions are: (a) The occurrences of heavy oils are not linked to a specific stratigraphic horizon; the API gravity of the expelled fluids, vary from 10 to >50, as a function of transformation ratio of the source rocks, (b) the distribution of heavy and light oils are controlled by both the expelled fluid composition and fluid propagation processes, (c) liquid-liquid fractionation is an important process which refines the quality of migrating oils, (d) gravitational fractionation is inevitable, and has a major impact on oil quality in long oil columns, (e) the recent discovery of the physics of petroleum expulsion has revealed the large forces involved in this process; fluids in reservoirs which move into the early expulsion fronts, are prone to be displaced by heavy fluids injected from the source rocks, (f) no relationship is observed between the thermal stability of the source rocks and the content of organic sulphur in their kerogen, and (g) the fluids expelled are predicted to be, for the most part, low shrinkage black oils with low saturation pressures. We will further present 2-D basin modeling of the area, and a realistic assessment of the resources, and show what fraction of the resources are good quality oils.