层序地层学研究及隐蔽油气藏预测——以南阳凹陷古近系为例
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摘要
高精度层序地层学已被证明是寻找隐蔽圈闭行之有效的理论方法.运用该理论对南阳凹陷进行了研究,对地震剖面中反射界面的追踪,在古近系中识别出了各级别的层序界面,结合周缘露头、钻井、测井等资料,分析了主要目的层序内体系域的构成及高频单元变化规律,建立了层序地层模式,在此基础上预测南部陡崖式断坡带和北部缓坡式弯折带是低位域砂体和隐蔽岩性油气藏形成的有利区带.
Nanyang Depression抯 Brief Introduction and Research Way Nanyang Depression is a Cenozoic half-graben. Its important explored horizon is Paleogene抯 Hetaoyuan Formation. Now we have discovered four oil fields (Dongzhuang, Weigang, Zhangdian and Beimazhuang) . Its cumulative proven reserve is 1656×104t. Its cumulative oil-bearing area is 31.9 km2.According to the achievement of resource assessment, its total oil resource is 6200×104t. Its remaining reserve resource capacity is 4500×104t, the potential is relatively huge. But it has been exploited for 3o years. The exploration degree is very high and there are many difficulties. Many big structural traps have been explored. We must completely research seismic and geological materials in a systematic way in order to find oil how to accumulate and how to form pools, to guide new exploration areas. Therefore there is profound significance to do High Precision Sequence Stratigraphic research and prediction about subtle pools for the first time in the depression. 2 High Precision Sequence Stratigraphic Research (1) Research way and sequence division .By synthesizing outcrops, drilling, logging materials etc,and completely tracing reflection characteristic of seismic sections, we distinguishes every sequence of different grade, and divide high frequency sequences of the important horizon to study their construction and evolution laws. Main dividing evidence:① seismic reflection character analysis: uncomformity interface due to cutting or erosion, dipositional onlap ,baselap and top lap; ② core,cutting logging and well logging materials; ③ system tract evolution; ④organism species; ⑤microelement change.Because of its ancient landform, the construction characteristic of high frequency sequences in III grade sequences are controlled by the northern bend-sloping region. The region becomes a favorable site for the later exploration to look for big fan bodies in LST. (2) Depositional system analysis of the important explored horizon.There are three big depositional systems. The first is the northern axial HST deltaic deposit, it includes Jiaodian-Shayan and Zhangdian-Jinhua multiple deltas. It is a main system in the Depression. The second is the fan-delta system of the southern actic region. It is a main depositional system in the southern actic region. Along the southern boundary fault, there are some small fan bodies. The third is LST fans in the northern bend-sloping region. The northern bend-sloping region is a main target site to look for subtle pools. (3) Sequence stratigraphic model.Nanyang Depression is a typical tectonic basin. Tectonic movement is important to the types and location of depositional systems. So Nanyang Depression has a unique compound sequence stratigraphic format with a gentle bend-sloping region and a fracture-sloping region. The change of Paleogene抯 accommodation space and the growth of sequences are mainly controlled by the southern listric growing fault. Along the fault, there are some small apron fan-deltas. In the northern bend-sloping region which is formed owing to the extending fold, there are some fan depositional bodies in LST and TST, and there is big axial multiple deltaic deposit in HST. From its north to its south, the sedimentary thickness suddenly changes. From it to the actic region, there are more sedimentary cycles, and the sequences of HST and TST are complete. LST sequences are mainly in the southern sloping region of the bend-sloping region, and there are some LST slope-fan bodies. In the bend-sloping region there are downcutting channels. So it becomes a key site to seek subtle lithologic pools and stratigraphic pools in the depression, and it is specially emphasized during we erect the sequence stratigraphic format. 3 Favorable Exploration Region Analysis and Prediction about Subtle Pools On basis of high precision sequence stratigraphic research, analysis of depositional systems and reservoir evaluation etc, linking with the pattern of petroleum migration and accumulation and hydrocarbon trapping mechanism ,we predic
Nanyang Depression抯 Brief Introduction and Research Way Nanyang Depression is a Cenozoic half-graben. Its important explored horizon is Paleogene抯 Hetaoyuan Formation. Now we have discovered four oil fields (Dongzhuang, Weigang, Zhangdian and Beimazhuang) . Its cumulative proven reserve is 1656×104t. Its cumulative oil-bearing area is 31.9 km2.According to the achievement of resource assessment, its total oil resource is 6200×104t. Its remaining reserve resource capacity is 4500×104t, the potential is relatively huge. But it has been exploited for 3o years. The exploration degree is very high and there are many difficulties. Many big structural traps have been explored. We must completely research seismic and geological materials in a systematic way in order to find oil how to accumulate and how to form pools, to guide new exploration areas. Therefore there is profound significance to do High Precision Sequence Stratigraphic research and prediction about subtle pools for the first time in the depression. 2 High Precision Sequence Stratigraphic Research (1) Research way and sequence division .By synthesizing outcrops, drilling, logging materials etc,and completely tracing reflection characteristic of seismic sections, we distinguishes every sequence of different grade, and divide high frequency sequences of the important horizon to study their construction and evolution laws. Main dividing evidence:① seismic reflection character analysis: uncomformity interface due to cutting or erosion, dipositional onlap ,baselap and top lap; ② core,cutting logging and well logging materials; ③ system tract evolution; ④organism species; ⑤microelement change.Because of its ancient landform, the construction characteristic of high frequency sequences in III grade sequences are controlled by the northern bend-sloping region. The region becomes a favorable site for the later exploration to look for big fan bodies in LST. (2) Depositional system analysis of the important explored horizon.There are three big depositional systems. The first is the northern axial HST deltaic deposit, it includes Jiaodian-Shayan and Zhangdian-Jinhua multiple deltas. It is a main system in the Depression. The second is the fan-delta system of the southern actic region. It is a main depositional system in the southern actic region. Along the southern boundary fault, there are some small fan bodies. The third is LST fans in the northern bend-sloping region. The northern bend-sloping region is a main target site to look for subtle pools. (3) Sequence stratigraphic model.Nanyang Depression is a typical tectonic basin. Tectonic movement is important to the types and location of depositional systems. So Nanyang Depression has a unique compound sequence stratigraphic format with a gentle bend-sloping region and a fracture-sloping region. The change of Paleogene抯 accommodation space and the growth of sequences are mainly controlled by the southern listric growing fault. Along the fault, there are some small apron fan-deltas. In the northern bend-sloping region which is formed owing to the extending fold, there are some fan depositional bodies in LST and TST, and there is big axial multiple deltaic deposit in HST. From its north to its south, the sedimentary thickness suddenly changes. From it to the actic region, there are more sedimentary cycles, and the sequences of HST and TST are complete. LST sequences are mainly in the southern sloping region of the bend-sloping region, and there are some LST slope-fan bodies. In the bend-sloping region there are downcutting channels. So it becomes a key site to seek subtle lithologic pools and stratigraphic pools in the depression, and it is specially emphasized during we erect the sequence stratigraphic format. 3 Favorable Exploration Region Analysis and Prediction about Subtle Pools On basis of high precision sequence stratigraphic research, analysis of depositional systems and reservoir evaluation etc, linking with the pattern of petroleum migration and accumulation and hydrocarbon trapping mechanism ,we predic
引文
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