Study On The Accommodation Space Transformation And Sedimentary System In Gunan Sag

According to the classic sequence stratigraphy concept, the change of the accommodation space of the basin is unified in the seesaw process of the sea level. However, based on the analysis and research on the accommodation space, it was found that because of the influences caused by differential base subsidence, sedimentary process and absolute lake level alternation, the changes of the accommodation space in faulted basin is ununified. On one side of the basin with severe fault movement, the increase of accommodation space caused by base subsidence is the largest. On the other side, due to the weaker fault movement, the increase of the accommodation space is relatively smaller and it can be even decreased in certain circumstance. Between the two parts, there could be a balance point which is called the accommodation space transformation point where the accommodation space is unchanged. The increasing, decreasing and transformation belt and its 3-dimentional distribution are called the accommodation space transformation system.According to the analysis above, combined with the former research result, the theoretical model and its components have been analyzed firstly. And the formula for calculating the position of the transformation point under the ideal condition has been put forward. At the same time, the composition and division scheme of the accommodation space transformation have also been expatiated. It is considered that in the period of Es3z member, the sedimentary system was controlled by the delta-fan delta-tempestite model. The main source of the sediment came from the uplift of Gudao, Kenli and Kendong.Taking the Es3z member as the researching object, according to the theory of accommodation space transformation system, it has been classified as a 3rd-level accommodation space transformation system. And furthermore, it can be subtly divided into 7 4th-level transformation systems. Under this framework, the sedimentary system distribution of these 7 layers has been systematically researched.Based on the research above, with the method of accommodation space transformation system and seismic data analysis, 7 cross sections have been made to decide the distribution situation of the accommodation. With the help of time-frequency analysis, the horizontal distribution of the Es3z member has been confirmed.At last, according to the theory of petroleum geology and the vertical sequence characteristics of the transformation belt, the relationship between the transformation belt and the reservoir forming has been discussed. And with the analysis of classical reservoir, it is considered that the transformation belt has controlling influence on the distribution of the oil and gas.