The Bongor Basin in southern Chad is an inverted rift basin located on Precambrian crystalline basement which is linked regionally to the Mesozoic – Cenozoic Western and Central African Rift System. Pay zones present in nearby rift basins (e.g. Upper Cretaceous and Paleogene reservoirs overlying Lower Cretaceous source rocks) are absent from the Bongor Basin, having been removed during latest Cretaceous – Paleogene inversion‐related uplift and erosion. This study characterizes the petroleum system of the Bongor Basin through systematic analyses of source rocks, reservoirs and cap rocks.Geochemical analyses of core plug samples of dark mudstones indicate that source rock intervals are present in Lower Cretaceous lacustrine shales of the Mimosa and upper Prosopis Formations. In addition, these mudstones are confirmed as a regional seal. Reservoir units include both Lower Cretaceous sandstones and Precambrian basement rocks, and mature source rocks may also act as a potential reservoir for shale oil. Dominant structural styles are large‐scale inversion anticlines in the Lower Cretaceous succession whilst underlying “buried hill” ‐type basement plays may also be important. Accumulations of heavy to light oils and gas have been discovered in Lower Cretaceous sandstones and basement reservoirs.The Great Baobab field, the largest discovery in the Bongor Basin with about 1.5 billion barrels of oil in‐place, is located in the Northern Slope, a structural unit near the northern margin of the basin. Reservoirs are Lower Cretaceous syn‐rift sandstones and weathered and fractured zones in the crystalline basement. The field currently produces about 32,000 barrels of oil per day.

: Exploration and development experience show that there is obvious oil gravity difference between the southern part and northern part of the “M1” reservoir in the Fanny oil field in the slope of the Oriente Basin, Ecuador. The American Petroleum Institute Gravity (API) values of oils in the northern part are higher than the one in the southern part of the Fanny oil field, with the values of 20° and 10.0°–13.0°, respectively. So the primary purpose of this study was to analyze the heavy oil characteristics of biodegradation and the oil–oil correlation according to the biomarker data and the δ13C signature of oil samples from T block. The results of the hydrocarbon gas chromatography fingermark and the inversion attribute characteristics indicated that there are fluid compartments between the “M1” reservoir of Fanny south. Finally, the models of oil–gas accumulation under the control of multiple‐activities of complicated fault systems, as well as the origin of heavy oil, are contended. The early stage oils from the western part of the basin were biodegraded heavily in varying degrees in the whole basin, and the later stage oils were derived from the southern part in a large scale and were mature and lighter. Generally, oil mixing is the primary control of net oil properties, such as API gravity in Oriente Basin. We therefore predicted that the API gravity variation of oil pools radically depends on the injection amount of the later stage oil. Because of the shale barrier in the “M1” reservoir of Fanny south, the later stage hydrocarbon could not pass through and contribute to increase the oil API value.

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The nuclear magnetic resonance (NMR) response is known to deviate from the true value for the volcanic reservoirs, particularly when the pore throat size is ultralow. Consequently, the related petrophysical parameters such as porosity, permeability, and pore size distribution from NMR measurements are greatly influenced. An empirical method to correct the NMR calibrated porosity for the tight volcanic rocks is proposed after comprehensive investigations of influential factors combined with mineralogical and petrophysical analyses. The laboratory result indicates that the relative porosity deviation is negatively correlated with the geometric mean of the transversal relaxation time (T2) but positively correlated with the clay content. Moreover, both the paramagnetic materials, such as the manganese (Mn) content, and the diamagnetic materials, such as the magnesium (Mg) content, contribute to the NMR relaxation intensity reduction but with different mechanisms. The NMR calibrated porosity can be compensated through multiple regressions with these controlling factors, which can be generalized to other tight volcanic reservoirs.

Nowadays, in the investment market, the investment method with major asset allocation as the core has become the mainstream of various industries. This paper studies the data of various macroeconomic indicators, screens these indicators and observes their changing trends, so as to divide the economic cycle, and uses time series analysis and calculation of the relevant characteristics of risk and return, so as to maximize the benefits of asset allocation. According to the Merrill Lynch "investment clock" theory, select four economic indicators, observe the general change trend of these four indicators in one, and divide them into five different stages of economic status. The APIMA time series model was used to calculate the changing trend of macroeconomic environment. Through mathematical statistics, economics and other relevant principles to calculate the risk and return characteristics of the five stages, presented by the correlation coefficient heat map.This paper analyzes the impact of monetary policy on the return of major assets at different stages of the economic cycle, which is conducive to improving the investment ability of various asset management companies, promoting the effectiveness of asset allocation, improving the annual return rate of asset allocation portfolio, and thus increasing economic benefits.