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Gao Z.,Petroleum Geology Research and Laboratory Center | Gao Z.,Beijing Petroleum and Oil Institute | Feng J.,Petroleum Geology Research and Laboratory Center | Feng J.,Beijing Petroleum and Oil Institute | And 4 more authors.
Oil and Gas Geology | Year: 2013

A brief analysis of vertical uplifting height and horizontal shortening on the thrust belt in foreland basins of the central and western China reveals that there are two types of forces that controlled the deposition of thrusting belt, one is the horizontal progress force and the other is the vertical uplifting force. The vertical lifting force gave birth to thrust faults. The vertical displacement by the force resulted in the uplifting of mountains and lowering of basins the thrust faults and created accommodation. The horizontal progress force generated strike-slip faults. The horizontal displacement by the force pushed mountains and provenance forward. Based on this understanding, the thrusting during the Paleogene-Neogene in southern margin of Junggar and Kuqa foreland basins can be divided into 5 stages that correspond to three sets of coarse grain deposits and two sets of fine grain deposits respectively. Among them, the conglomerate at the bottom of the Palaeogene was the product of terrigenous clastic deposition in the stage dominated by horizontal progress force (together with auxiliary vertical uplifting force) and also marks the existence of a over-thrusting in the early Himalaya movement; the conglomeratic coarse-grained deposits at the bottom of the Neogene were the result of thrusting under the dominant horizontal progress force in the early thrusting loading period and also marks the renewal activity of over-thrusting during the early-middle Himalaya orogeny; and the conglomeratic coarse-grained deposits at the bottom of the Kuqa-Dushangzi Formation at the top of Neogene were formed during the middle-late Himalaya orogeny when the base rebound and provide large amount of sediments and caused sandbody progradation under horizontal progress force. While another two sets of Paleogene and Neogene lacustrine mudstone deposits were formed in a period with vertical uplifting force predominant when mountain uplifting caused piedmont flexural subsidence being enhanced and lake level rising.

Gao Z.,Petroleum Geology Research and Laboratory Center | Gao Z.,China National Petroleum Corporation | Cui J.,Petroleum Geology Research and Laboratory Center | Cui J.,China National Petroleum Corporation | And 9 more authors.
Shiyou Xuebao/Acta Petrolei Sinica | Year: 2013

The burial history for reservoirs of foreland basins in the central and western China is characterized by long-term shallow burial at the early stage and rapid deep burial at the late stage. Under a geological process constraint, we conducted a series of simulation experiments on diagenesis and analyzed the burial compaction process of deep reservoirs in the Kuqa foreland basin and its reworking effect. By quantitative evaluations of reservoir physical property parameters, such as plane porosity, apparent compaction percentage, porosity reduction rate, pore and neck diameters, a direct effect of burial compaction on the apparent compaction percentage and porosity reduction rate was verified, meanwhile, burial compaction of reservoirs was found to control variations in pore and neck diameters of sandstones with different grain size. At the early slow and shallow burial stage, compaction might result in not only less grain crackles as well as grain displacement and rearrangement in clastic rocks, such as coarse and mesograined sandstones, but also a random grain arrangement of aphanides, such as packsands and siltstones. At the late rapid burial compaction stage, along with increasing burial depth, compaction might lead to an oriented arrangement tendency for skeleton grains, and crackles and diagenetic fractures widely developed in clasitc grains representative of near-source deposition, such as coarse and mesograined sandstones, while siltstones deposited in foredeep belts showed less-developed grain crackles but some diagenetic fractures. Therefore, crackles and diagenetic fractures of clastic grains formed under rapid-deep burial are attributed to a major cause for dissolution occurrence and permeability enhancement of deep reservoirs.

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