The Effect Of Fualting On Sedimentary System

Bai Yun Sag is one of the most potential areas for enough oil resource、superior accumulation、good migration-accumulation and conservation condition, so Bai Yun Sag and surrounding areas have good conditions for hydrocarbon acumulation. However, faults are abundantly developed between Panyu uplift and Baiyun Sag that have important affection on palaeogeomorphology. palao-water depth and aource channel, and make types of sediment and distribution morphology different which can affect difference between reservoir property and porosity;Faults not only can grooming or sealing oil nigration, but also play an important role in hydrocarbon acumulation, though previous searchers make a lot of research on faults of this area, the lack of researching the action of synsedimentary antithetic fault and affection to deposition systemBasing on previous researches, this article guided by structural geology、 sequence stratigraphy and sedimentology with seismic. core. logging and mud logging data which help the search of character of synsedimentary antithetic fault and affection on deposition system in Panyu uplift to Baiyun Sag, and analysis the control of synsedimentary antithetic faults to sedimentary systems.This article firstly use structure interpretation of2D seismic data, and then make quantitative study of geometric and action charecters of synsedimentary antithetic faults in Panyu uplift to Baiyun Sag by growth index, fault throw and fault activity rate, and analysis action of every main faults in the same time. There are many antithetic normal faults developed in Panyu uplift to Baiyun Sag and some are synsedimentary, the trend of these synsedimentary antithetic normal faults are often NWW and EW with steep section,and platy and spade apperence in profile, much secondary faults and major fault compose many combination forms,such as graben and horst、ladder-like and floweriness structure. The fault form on plane are most S-shaped,and secondary faults developed in the end of fault with inclined、parallel、 cauda and goose series plane combination form.The activity of fault showed intermitent with strong and weak interaction phenomenon. The main action time are early stage of Zhu Jiang upper segment,and the end stage of Han Jiang upper segment affected by Dongsha Movement, activities of synsedimentary faults are more strong. In the deposition time of lower segments of Zhu Jiang and Han Jiang. Yue Hai formation, the activities are weak. On the plane, fault activity in east of Pan Yu uplift is stronger than west, north is stronger than south. Through the comprehensive analysis of core observation, logging characteristics, seismic reflection configuration and the percentage of sandstone, we researched the sedimentary facies at the Miocene in Panyu low-uplift to Baiyun Sag. The region of interest mainly developed delta, shallow continental shelf and bathyal r. The delta front and prodelta deposition mainly develop in the Zhujiang and Hanjiang Formation, and shallow continental shelf deposition in the Yuehai Formation of Panyu low uplift zone. In the North Slope of Baiyun Sag hemipelagic deposition is dominated and deep-water fan deposit is multiply growth, with significant slump in the Yuehai Formation.Based on the analysis of the thickness of the layer time, the effect of synsedimentary fault on the deposition system is studied, combining with the control on accommodation space. When the fault is the activities of the weak fault activity, low accommodation of the thrown side is filled, and the sediment will continue be able to stack on the uplifted side, thus the shelf-margin delta develop at the shelf break in the northern Baiyun Sag. In the lower Zhujiang and the lower Hanjiang Formation,it is obvious that small difference of the formation thickness in the two sides of the fault, close sandstone content, the consecutive sedimentary facies and weak sediment barrier of reverse synsedimentary fault. The strong fault activity, controlling the ancient geomorphology, makes the big difference of thickness and the gap of sandstone content between the upper and lower side. Sediments pack along the fault on the thrown side with large accommodation, while a small number of fine-grained sediment on the uplifted side. In the northern slope of the Baiyun Sag, it is dominated by shaly deposition. Due to the the strong sediment barrier formed by the reverse synsedimentary fault, the sedimentary facies change significantly, which is significantly in the upper Zhujiang, the upper Hanjiang and the Yuehai Formation.Moreover, We further analysis the affection of fault activity on the deposition of sand body from the wertical and horizontal orientation. through the strata correlation section, we find when the weak activity of fault, create small accommodation space by downthrow block, the thickness and percentage of sandstone in the hanging wall and footwall is near. but when the strong activity of fault, create large accommodation space by downthrow block, sand body deposition along the fault trend, fine grain sediment deposited on the hanging wall with streams, which cause the thickness the number of layer and percentage of sandstone larger than footwalls’. and analysis the equilibrium and different activity through the formation thickness. downthrow block entirely by equilibrium activity, which cause large accommodation space, sand body deposit the accommodation space along the fault trend, and apparently resist the sandbody deposit to Baiyun Sag. The different activity develop low-lyings, which cause part of sandbody deposit in the low-lyings, and part deposit on the uplifted wall through the weak activity of fault...