Analysis and interpretation of environment sequence models of the Hassi R'Mel Field in Algeria

摘要

With a surface area of 400,000 km~2, the Triassic Province in Algeria represents a vast Saharan territory, in which significant hydrocarbon layers are exploited on the Triassic and Cambrian-Ordovician levels. The Saharan Triassic consisted of varied continental environments, namely, fluvial, flood plain, lake, Sebkha, and wind. At the top of Formation I, the lower series of strata of the Triassic, there are intercalations of volcanic rocks represented by dolerites. Sedimentation interspersed with periods of no deposition is thought to have occurred during the Triassic continental; resulting in a deposition of ground-level strata and the development of a more or less intense paedogenesis. This paedogenesis is found at the origin of important unequal discontinuities which can be used for sequential cutting and is also significantly influenced by climate. In such a context, and during the periods of no deposition, physicochemical phenomena related to the climate and type of bedrock occur, leading to the formation of a more or less advanced ground related to the elapsed time between two phases of sedimentation; this phenomenon is known as paedogenesis. Formation II is characterized by the eruptive on the level of the lower member IIa at the base and constituted primarily of dolerites but the roof is primarily by a channel in a fine sandy filling. The member IIb is characterized by fluvial facies of channels prevailing and evolving to the top in a complex of playa or evaporates. This complex is characterized by a negative polarity at the bottom with a broad separation of the curves of neutron/density. Formation III is characterized primarily by an evaporate facies of sebkha type halite which separates by electro halite benches, with weak Gamma Ray and lower than 10 API. The sonic signal is relatively constant around 70 μs/ft. This work therefore attempts to refine the above models by using a well log-based modeling approach (gamma ray, neutron, sonic, density and resistivity) to examine the evolution of successions. The stratigraphy obtained using the results of faciologic analysis established for this purpose on the level of the Hassi R'Mel field is also used.