Favorable area evaluation

According to the results of zoning optimization, the layered system evaluates favorable zones from structural conditions, source-reservoir-cap allocation, reservoir-forming conditions, key factors of oil and gas accumulation, zoning resources and so on.

(1) Mesoproterozoic favorable zone

The key areas include Puhe anticline belt, Kunming Lake anticline belt and Fenghe anticline belt.

1. Puhe anticline belt

Located in the strategic area of Dangba sag in the north of Hebei Province, it belongs to ⅱ 1 superimposed structural unit type and is covered by Mesozoic above Mesoproterozoic. It is located about 10km west of Huapigu Reservoir. The exploration division of the former new area of China Petroleum and Natural Gas Group Company conducted a high-precision MT area survey in 1994 ~ 1995, and found this structure.

Structural characteristics of (1)

According to a north-south seismic survey line along the structure (Figure 6-2-3), it is found that the width of the structure is 7.5km from north to south, and the stratigraphic dip in the south wing is 13, and the stratigraphic dip in the north wing is 10. The estimated trap area is 10km2, and the closed range is 400～500m. ..

Fig. 6-2-3 Geological Profile of Line JB-95- 18 of Kuancheng Fault Depression Earthquake

(According to Huabei Oilfield, 2006)

(2) Characteristics of source rocks, reservoirs and caprocks

The source rocks are mainly shales of Hongshuizhuang Formation and Xiamaling Formation, and carbonate rocks of Wumishan Formation can also be used as effective source rocks. Mesoproterozoic and Paleozoic are well preserved in this area, and there are three complete sets of reservoir-cap assemblages, namely Wumishan Formation reservoir-Hongshuizhuang Formation cap, Tieling Formation cap-Xiamaling Formation cap, Cambrian-Ordovician reservoir-Carboniferous-Permian cap.

(3) accumulation

Before the middle Jurassic sedimentation, compressional folds occurred in the middle Neoproterozoic, and the structure began to take shape. In the Middle Jurassic, a stratum with a thickness of about 1200m was deposited, and the Ro value was about 1.0%. The source rocks entered a large number of hydrocarbon generation stages, which was the main hydrocarbon generation stage in the middle Neoproterozoic (Figure 6-2-4) and also the main migration and accumulation stage. It belongs to ⅱ 1 superimposed unit secondary hydrocarbon generation and accumulation model.

(4) Preservation conditions

The time of oil and gas accumulation in this area is early, and the traps in this area were destroyed to some extent by tectonic activities in the late Yanshanian and Himalayan period. Preservation conditions are the key factors for the existence of ancient oil reservoirs. Because this area was covered by Jurassic, it was well preserved in Paleozoic, and there was no fault that broke to the surface in the covered area of Jurassic. The mudstone caprock of Xiamaling Formation is 200 ~ 300 m thick, and the caprock of Hongshuizhuang Formation is 100 ~ 160 m thick, which is favorable for preservation.

(5) the number of resources

The resources estimated by trap method are1147.5×104t.

Based on the analysis of the above factors, Puhe anticline belt has the geological conditions for the formation and preservation of ancient oil and gas reservoirs, and is a favorable exploration zone for Mesoproterozoic.

2. Kunming Lake anticline zone

It belongs to the strategic area of Mesoproterozoic Jingxi sag, and is a anticline structure discovered by Wang Xingshi in North China Oilfield in the early 1980s on the basis of ground survey, gravity survey and shallow hydrological drilling.

Structural characteristics of (1)

Kunming Lake structure is a high point at the northeast end of Hongmiaoling-Badachu anticline (Figure 6-2-5, Figure 6-2-6). The eastern end is oblique to Babaoshan fault. North to Yuquan Mountain-Wanshou Mountain, south to at least Fu Temple, west to Wang Rui Tomb, east to Haidian along the long axis of Wang Rui Tomb-Zhongwu-Haidian, extending northeast. The core is composed of Lower Ordovician with an inclination of about 10, and the wing is composed of Middle Ordovician, Carboniferous-Permian and Lower Jurassic, with an inclination of 45 in the north wing, 20-25 in the south wing, 23-30 in the west end and about 165438 in the east end.

(2) Source-reservoir-cap assemblage

The main source rocks and caprocks are Mesoproterozoic Hongshuizhuang Formation and Xiamaling Formation. Two sets of regional reservoir-cap assemblages in Mesoproterozoic are well preserved (Table 6-2-22).

Figure 6-2-4 Buried Depth and Hydrocarbon Generation Evolution History of Each Layer in Pingquan Area of Northern Hebei Depression

Figure 6-2-5 Structural Map of the Top of Proterozoic in Kunming Lake Anticline

(According to Wang Xingshi 1988)

(3) accumulation

The evolution degree of source rocks is relatively high, with the upper part reaching the stage of moisture, the middle and lower part possibly reaching the stage of methane gas, and the main hydrocarbon generation stage is Yanshan period. The Yanshanian compressional activity formed structures, and oil and gas migrated and accumulated to form reservoirs. At the end of Yanshan period, the structure was uplifted and denuded, and the Permian-Ordovician at the core of the structure was denuded, only the Cambrian covered the Mesoproterozoic, and the oil and gas reservoirs were adjusted. It belongs to ⅱ 1 superimposed secondary generation reservoir model.

Figure 6-2-6 Structural Profile of Kunming Lake

(According to Wang Xingshi 1988)

Table 6-2-22 Combination Table of Jixian-Cambrian Source-Reservoir-Cover in Kunming Lake Structure

(4) Preservation conditions

Because the oil and gas reservoir was formed in Yanshan period, it experienced structural activities in late Yanshan period and Himalayan period after its formation. On the one hand, the anticline is required to remain intact, and if there is a roof-breaking fault, oil and gas cannot be preserved. The sealing property of the Middle-Neoproterozoic and Cambrian caprocks determines the preservation conditions and the amount of oil and gas lost by the diffusion of caprocks. So the preservation condition is the key. As a cap rock, the thickness of Xiamaling Formation is 200 ~ 300 m, and that of Hongshuizhuang Formation is 80 ~ 120 m, and the shale overlying the Middle and Lower Cambrian can also be used as a secondary cap rock.

(5) the number of resources

The resources estimated by trap method are 56 10× 104t.

3. Fengheying anticline belt

Located in the strategic area of central and northern Hebei in Mesoproterozoic, it is a structure discovered by two-dimensional seismic lines in North China Oilfield.

Structural characteristics of (1)

The top trap area of Mesoproterozoic Wumishan Formation is 20km2, the amplitude is 200 (north high point) ~400m (south high point), and the buried depth of the high point is 3000m (Figure 6-2-7). Well Jing 10 1 has been drilled in this structure, with a depth of 4,000m and Wumishan Formation at the bottom. The well location deviates from the main high point of anticline, about 400 meters lower than the high point, and there is no obvious oil and gas display during drilling.

(2) Source-reservoir-cap assemblage

Source rocks include Mesoproterozoic Wumishan Formation, Hongshuizhuang Formation and Xiamaling Formation.

The main caprock is a set of shallow sea Niping shale mixed with marl above CAMBRIAN Fujunshan Formation, Maozhuang Formation and Xuzhuang Formation, with a thickness of more than 200m, which can be combined with underlying Fujunshan Formation dolomite, Qingbaikou Jingeryu Formation limestone and Changlongshan Formation sandstone to form 1 reservoir-cap combination. The shale source rocks of Xiamaling Formation, the underlying Tieling Formation reservoir, the source rocks and caprocks of Hongshuizhuang Formation constitute a complete secondary reservoir-cap assemblage. The source reservoir of Wumishan Formation and the overlying source caprock of Hongshuizhuang Formation constitute the third set of source reservoir cap assemblage. The main Neoproterozoic source rocks drilled by Jing 10 1 Well are Xiamaling Formation, Tieling Formation, Hongshuizhuang Formation and the upper part of Wumishan Formation from top to bottom. The source rocks are 200m, 350m, 100m and 500m respectively, and the organic carbon content is 0.49% and 0.365438 respectively.

(3) accumulation

Anticline was first formed in Indosinian movement at the end of Triassic, and Yanshan movement was further strengthened. Since then, long-term uplift and erosion. The Himalayan Mesoproterozoic buried depth was more than 8000 meters, and it entered the stage of secondary hydrocarbon generation. At this time, the structure has been formed, and oil and gas can enter the trap through adjacent reservoirs and faults. It belongs to the I-type superimposed secondary generation reservoir model (Figure 6-2-8).

Figure 6-2-7 Structural Map of the Top of Wumishan Formation in North-Central Hebei Province

(According to Huabei Oilfield, 2006)

Figure 6-2-8 Mesoproterozoic Reservoir-forming Model of Wind-wind Joint Venture

(4) Secondary hydrocarbon generation

Fengheying structure is relatively complete and reservoir-cap assemblage is developed. Because of the strong uplift at the end of Yanshan period, the hydrocarbon accumulation depends on the secondary hydrocarbon generation in Himalayan period, so the main controlling factor is the secondary hydrocarbon generation in Himalayan period. According to the simulation calculation, the hydrocarbon generation intensity of Mesoproterozoic Himalayan period can reach (70 ~ 120) × 104t/km2, and the secondary hydrocarbon generation conditions are good.

(5) the number of resources

The resources estimated by trap method are 2040× 104t.

(2) Paleozoic favorable zones

1. Wang Guan Tunduan Nose Belt

The nose zone in Tun section of Wang Guan belongs to the strategic area in the south of Paleozoic Huanghua, and it is an I-type superimposed unit. Located in the south-central part of Huanghua Depression, between Cangdong Depression and Yanshan Depression (Paleogene-Neogene), it forms Kongdian structural belt together with Kongdian uplift, Kongxi nose anticline and Kong72 fault nose. Paleozoic industrial oil flowing well 1 well (Konggu 3), Paleozoic industrial oil flowing well 1 well (Konggu 4), 2 water producing wells (Konggu 1 well and Konggu 7 1 well) were found in Kongdian structural belt, and 3 wells (Konggu 72) were found. The Mesozoic reservoir associated gas δ 13C 1 in well Guan 142 located in the northeast of the structure is relatively heavy, ranging from-33 ‰ to-32 ‰, and the coal-formed gas content is relatively high.

Structure and evolution characteristics of (1)

Wang Guan Tun buried hill structure is located at the southwest end of Kongdian structural belt, which is an anticline structure attached to Kongdong fault. The structure was formed earlier, and it is a concave-middle-long paleostructure. The structural strike is northwest, with a buried depth of 4,350m, a trap area of 28km2 and an amplitude of 400m (Figure 6-2-9).

Figure 6-2-9 Structural Map of Wang Guan Tun Buried Hill

(According to Dagang Oilfield 1994)

Wang Guan Tun structure, which was formed in the late Yanshan period, is a relatively complete anticline structure. During the late Cretaceous-Paleocene, the whole uplift was denuded, and most of the Mesozoic strata at the top of the structure were denuded, and there were relatively complete Triassic and middle and lower Jurassic in the wing. In Eocene, the paleotopography was low in the west and high in the east, and the amplitude of anticline traps decreased. By Oligocene, the Kongtong fault began to develop, the rising plate was strongly tilted, the northeast wing of Wang Guan Tun structure was uplifted, and the trap amplitude was further reduced. Although the amplitude is reduced, the current structural amplitude is still very large.

(2) Source-reservoir-cap assemblage

Paleozoic source rocks are thick and rich in organic matter. Two sets of regional reservoirs are Permian Upper Shihezi Formation, Lower Shihezi Formation sandstone and Ordovician top weathering crust. Carboniferous-Permian caprock is thick. The total thickness of Permian Shiqianfeng Formation and Triassic mudstone is 652 meters (Guangu 1 well), which can be used as the direct caprock of Carboniferous-Permian. Carboniferous is about 250 meters thick and can be used as Ordovician caprock. Although there are several faults cut in the high part of the structure, these faults have short offset and short development time, and generally do not divide Carboniferous-Permian system.

(3) accumulation

The Cenozoic tectonic activities adjusted the traps formed in the early stage, but they were complete in shape and accumulated a large amount of oil and gas, and the tectonic formation period matched the oil and gas migration (Figure 6-2- 10). It belongs to type I superimposed secondary hydrocarbon generation and accumulation model.

(4) Conditions of source rocks

According to the analysis of source rock conditions, the intensity of secondary hydrocarbon generation in Himalayan period was greater than 200× 104t/km2 in Paleozoic, but the hydrocarbon supply area was relatively small, the trap fullness might be small, and the resources estimated by trap method might be large.

Fig. 6-2- 1 Wang Guan Tun Buried Hill Accumulation Model

(5) the number of resources

According to the trap area in this area, the estimated natural gas resource is 659.0× 108m3.

2. Acropolis-Liuwen Buried Hill Belt

Located in the north of the central uplift belt of Dongpu sag, it is a ⅱ-4 superimposed unit. Seven exploratory wells have been drilled in this area. Except for Gu Wei 1 well and Guwei 2 well, the other 5 wells show good oil and gas performance. The carbon isotope methane value of Carboniferous-Permian natural gas in Well Wen Gu 2 is-29.6 ‰; Ethane -24.3‰, propane -2 1.4‰, butane -25.7‰, rare gas He3/He4 ratio of 0.889× 10-7, and Ar40/Ar36 isotope value of141.

Structure and evolution characteristics of (1)

Controlled by Wenxi-Weixi fault, the stratum generally inclines eastward, and the top surface is broad and gentle, with an area of 120km2. There are three structures locally, Wenmingzhai, Weicheng and Liuwen Buried Hill, which are in the form of broken nose, semi-anticline and broken anticline respectively, among which Liuwen Buried Hill has the largest structural area (Figure 6-2- 1 1). The overlying strata of the buried hill are complete, with three-dimensional coverage and structural implementation.

Buried hill belt developed in Paleogene, which is a Cenozoic inherited depression and uplift. Dongpu sag was dominated by integral depression in Neogene, and the structure also stopped moving.

Fig. 6-2- 1 1 Acropolis-Liuwen Buried Hill Belt Structural Map

(According to Zhongyuan Oilfield, 2002)

(2) Source-reservoir-cap assemblage

Carboniferous-Permian can form three reservoir-forming combinations: self-generation and self-storage, Paleozoic middle storage and Paleozoic new storage. Cambrian-Ordovician can form Carboniferous-Permian source rocks, Cambrian-Ordovician reservoirs and Carboniferous-Permian caprock combinations.

(3) accumulation

There was no secondary hydrocarbon generation in Yanshan period in Dongpu sag, and the peak of secondary hydrocarbon generation was in Himalayan period, which matched the structural formation. It belongs to Ⅱ-4 superimposed secondary generation reservoir model (Figure 6-2- 12).

Fig. 6-2- 12 Liu Wen's Paleozoic reservoir-forming model

(4) Reservoir physical properties and lateral plugging

Because this area is a fault anticline, a fault block trap with large fault distance, and Palaeozoic and Paleogene are in lateral contact, it requires good lateral sealing conditions. According to the analysis of Well Wen 23, Well Wen 2 and Well Wei 79-9, the pre-Paleogene oil and gas can be accumulated in Paleozoic, Mesozoic and Cenozoic.

The Paleozoic secondary hydrocarbon generation time is late, the oil and gas filling is also late, and the diagenesis time is long. The physical properties of Paleozoic reservoirs determine the oil and gas enrichment.

(5) the number of resources

According to the trap area in this area, the estimated natural gas resources are 574.9× 108m3 and 0.3×108t (330×108m3) respectively.

3. Tangyi anticline structural belt

It belongs to the strategic area of the Paleozoic Linqing Depression, and the Tangyi uplift belt belongs to the Ⅱ1type superposition type, while Shenxian, guanxian sag and secondary steps belong to the Ⅰ type superposition type.

Tangyi structural belt is located in the east of Linqing Depression, bordering Shenxian Depression in the east and guanxian Depression in the west. It consists of Gaotang, Kangzhuang and Tangyi structures in the north.

Eight wells have been drilled in Gaotang and Tangyi structural belts, namely Kanggu 1, 2, 4, Tanggu 1, 4, Hua 4, Xin 3 and Tanggu 5. There are 6 wells showing oil and gas, among which Kanggu 1 well shows 7 layers of oil-stained limestone in the weathering crust at the top of Ordovician, with a thickness of 7.3m. Take out the core with a specific gravity of 0.887, indicating oil leakage. The tested water production of this layer is 42.22m3/d, and the well Gaogu 4, which is located in the east second order, was tested at 4514 ~ 4,525m on March 6th, and the natural gas was 2039m3/d and the oil was 2.04t/d from the 4mm choke. After fracturing, the maximum daily production of natural gas is 2. 1× 104m3, and the cumulative production of condensate oil is 30. 18t.

Structure and evolution characteristics of (1)

It includes six semi-anticlines or fault blocks, such as Kangzhuang, Kangzhuang North, Kangzhuang South, Tangyi, Tangyi East and Tangyi South. The trap area is large, the amplitude is high, and the total trap area is 183km2(Tg2). The main traps are Kangzhuang, Tangyi and Tangyinan, with trap areas of 30km2, 56km2 and 70km2 respectively, *** 156km2. The main traps are Kangzhuang, Tangyi and Nantangyi, with an area of 30 ~ 70km2 and amplitudes of 400m, 1300m and 900m respectively. They are all semi-anticlines or broken anticlines (Table 6-2-23).

In Yanshan period, Tangyi uplift had reached a certain scale, and Paleogene was the main formation stage of this structure. There are two steps on both sides of the structure, and the strata tend to both sides, with consequent faults.

(2) Source-reservoir-cap assemblage

There are two sets of good source rocks: CAMBRIAN-Ordovician and Carboniferous-Permian. The reservoirs are paleoweathering crust at the top of Ordovician and Carboniferous-Permian sandstone. The former has good physical properties and the latter has poor physical properties. The porosity is generally 3.6% ~ 4.3%, and the permeability is generally (0.01~ 0.02) ×10-3 μ m2. The coal-bearing stratum about 300 meters below Carboniferous-Permian is a good cover of Ordovician, and the Permian-Triassic is a regional cover of Permian reservoir with interbedded sandstone and mudstone.

Table 6-2-23 Table of Trap Elements in Tangyi Structural Belt

(3) Accumulation and key factors

Taking Gaogu 4 well as an example, the source-reservoir-cap assemblage is developed, the cap rock is good and the reservoir is poor. The main reservoir-forming period is Himalayan period, which belongs to type I superimposed secondary hydrocarbon generation and reservoir-forming model.

Well Gaogu-4 trap is located at the second step in the east of Tangyi Buried Hill Belt, and it is a fault nose structure (Figure 6-2- 13 and Figure 6-2- 14). The Paleozoic source rocks in Jiangdian sag have the conditions of secondary hydrocarbon generation in Himalayan period. Carboniferous-Permian sandstone is dense, low porosity and permeability, and primary pores are undeveloped, mainly secondary dissolved pores and micro-fractures. The caprock in Fuxiaohe area is widely distributed in this area, with a thickness of about 200 meters and a mudstone ratio as high as 70%.

Fig. 6-2- 13 Tg structural map of kangzhuang-jiangdian

Fig. 6-2- 14 Reservoir Profile of Well Gaogu 4

The lateral sealing of faults is the key to reservoir formation. Paleozoic faults developed, but most of them originated from Mesozoic or Es4-Kongdian Formation, and ended in Mesozoic or Es4-Kongdian Formation, which is not connected with faults generated since Paleogene. The peak of secondary hydrocarbon generation is from Guantao Formation to the present, when the ancient fault system has stopped moving, and the sealing of the fault depends on the formation lithology on both sides of the fault. Well Gaogu 4 is a fault block trap controlled by reverse faults. Among them, the distance between the two plates of the NE-trending fault is 400m, which makes the sandstone in Kuishan-Wanshan section of the ascending plate of the target interval butt with the lower Mesozoic of the descending plate. Mesozoic sandstone developed in Gaogu 4 well area, especially the lower sandstone with large single layer thickness, coarse lithology and relatively good physical properties, which is not conducive to lateral sealing, resulting in no thick sandstone accumulation in Kuishan-Wanshan section of Gaogu 4 well.

At the height of the uplift, Paleozoic also suffered some erosion. The distance between east and west faults in Tangyi is large, exceeding 1000m, and the fault system is developed, so the lateral sealing of caprock and fault is very important.

Paleozoic source rocks in Shenxian and guanxian Sags on the east and west sides of Tang Yilong are deeply buried. The source rock is thick, the Carboniferous-Permian dark mudstone is generally larger than 100 m, and the coal seam is larger than 100 m ... The secondary hydrocarbon generation intensity of Ordovician Himalayan in Shenxian sag is (40 ~ 80) × 104 t/km2, and that of Carboniferous-Permian Himalayan is (50). However, the intensity of secondary hydrocarbon generation in Himalayan period in guanxian sag is less than 100× 104t/km2, which is not conducive to hydrocarbon accumulation.

(4) the number of resources

The trap method estimates that the natural gas resources in Tangyi uplift are 575.4× 108m3.

4. Tangzhuang-Machang Buried Hill Belt

It belongs to the strategic area of Dongpu Depression and is a ⅱ-4 superimposed unit.

At present, many exploratory wells such as Magu 1, 2, 5, 6, 1 1, Kai 33, Ma 3, 17, 2 1 and 50 have been drilled to the Paleozoic in this area, and many wells are different in Ordovician.

Structure and evolution characteristics of (1)

Xuji-Machang-Sanchunji is a north-south trending basement paleouplift belt, which is divided into Xuji, Machang and Sanchunji structures by Machang fault and Sanchunji fault. Four local structures such as Magu 6, Magu 5, Magu 16 and Magu1are developed in Tangzhuang-Machang area from south to north (Figure 6 Machang

This structural belt is a Paleogene inherited uplift, with strata inclined eastward and deep depressions on both sides.

(2) Source-reservoir-cap assemblage

The main source rock is Carboniferous-Permian coal measures, which has a high degree of thermal evolution and is adjacent to deep depressions in the east and west, and has the conditions for secondary hydrocarbon generation.

Buried hill has been eroded for a long time, and the reservoir has been dissolved and reformed, and fractures and caves are developed, which has good reservoir conditions. The caprock is Carboniferous-Permian, and the lateral caprock is Carboniferous-Permian and Member 4 and Member 3 of Shahejie Formation.

Fig. 6-2- 15 Structure Diagram of Tg Reflector in Racecourse Area

(According to Zhongyuan Oilfield, 2002)

(3) accumulation

Ordovician carbonate rocks and weathered crust can directly contact with Carboniferous-Permian coal-bearing strata in a large area through faults, which has good conditions for capturing coal-formed gas and is beneficial to the formation of Paleozoic ancient reservoir gas reservoirs (Figure 6-2- 16).

(4) Secondary hydrocarbon generation in Himalayan period.

Hydrocarbon generation in this area is earlier, and the secondary hydrocarbon generation in Cambrian-Ordovician Himalayan period is less than 10× 104t/km2, and that in Carboniferous-Permian Himalayan period is (40 ~ 80 )× 104t/km2.

Fig. 6-2- 16 Oil and gas accumulation pattern diagram of Machang structure

(5) the number of resources

According to the trap method, the estimated natural gas resource is 883.5× 108m3.

5. Sicundian-Wharf Fault Block Structural Belt

Sicundian-Wharf fault block structural belt belongs to the strategic area of central and northeastern Hebei, and is an I-type superimposed unit. Located in the east of Damengzhuang sag in the west of Wuqing sag (Figure 6-2- 17 and Figure 6-2- 18), the favorable exploration area is 450km2. At present, 6 wells have been drilled in this depression, but only Su 50 well has encountered Ordovician, and the daily natural gas production of Ordovician is over 500m3, and the remaining 5 wells have encountered Mesozoic and Paleogene.

Structure and evolution characteristics of (1)

Buried hill is an inclined fault-block mountain with northeast distribution, which is controlled by Damengzhuang fault in the west and Sicundian fault in the east. It is composed of Carboniferous-Permian, Ordovician and older strata. Qianshan fault is the main fault that controls the mountain, with Mesozoic in the east and no Mesozoic in the west. The structure began to form in Paleogene. The Ordovician high point of buried hill has a buried depth of 6300m, a closed range of 700m and a closed area of 80km2. The high point of Permian trap is buried at a depth of 5500m, with an amplitude of 500m and a closed area of 3 1km2.

(2) Source-reservoir-cap assemblage

Fig. 6-2- 17 Structural Profile of YC-9 1.5 Survey Line of Sicundian Buried Hill

Carboniferous-Permian is the main source rock of Paleogene, with two sets of main reservoirs (Ordovician carbonate rocks and Permian Shihezi Formation sandstone) and multiple sets of caprocks, which constitute various types of source-reservoir-cap assemblage, including epigenetic-lower reservoir assemblage and authigenic-self-reservoir assemblage. Carboniferous-Permian residual thickness is 700 ~ 900 m, which is in the secondary hydrocarbon generation stage of dry gas. There are two sets of reservoirs, Ordovician carbonate rock and Permian Shihezi Formation sandstone, which are mainly secondary pores and structural fractures formed by dissolution. Ordovician carbonate rocks in Sicundian buried hill are covered by coal measures strata of benxi formation-Shanxi Formation of Carboniferous in Lower Permian, with a thickness of 300-400 m, mainly mudstone, aluminum mudstone and coal seam, which can be used as direct cover. The sandstone reservoir of Shihezi Formation in Permian has mudstone caprock of Shiqianfeng Formation, and its thickness exceeds 100m.

Figure 6-2- 18 Comprehensive Geological Map of Pre-Paleogene in Wuqing Depression

(According to Huabei Oilfield, compiled and drawn)

(3) accumulation

On the west side of the buried hill, the source rocks of the third member of Shahejie Formation and the upper member of Shahejie Formation of Paleogene are connected with the buried hill reservoir. Dark mudstone is developed and has strong sealing ability. Buried hill formation at the end of Paleogene (Figure 6-2- 19). At this time, the top buried depth of Carboniferous-Permian in Damengzhuang sag has reached more than 5000 meters (west of buried hill). It has the conditions for secondary hydrocarbon generation. At present, the buried depth of source rocks from the third member of Shahejie Formation to the fourth member of Shahejie Formation in Paleogene has reached more than 6000m, and it has entered a stage of massive gas generation, and the reservoir-forming period is the late Himalayan period. It belongs to type I superimposed secondary generation reservoir model.

Fig. 6-2- 19 Structural Development Profile of Northern Jizhong Depression

(4) lateral plugging

Buried hill was formed at the end of Mesozoic and fixed at the end of Paleogene, and its structure was formed before the peak of hydrocarbon generation. The intensity of secondary hydrocarbon generation in Himalayan period is more than 250× 104t/km2, and the hydrocarbon generation conditions are very good. The third member of Shahejie Formation is connected with the upper member of Shahejie Formation, and lateral plugging is the key.

(5) the number of resources

According to the trap method, the estimated natural gas resources are 2 103.5× 108m3.

(3) Mesozoic favorable zone

1. Sanjiebao-Qinglongtai Buried Hill Structural Belt

It belongs to the strategic area of the eastern sag of Liaohe River, and it is a Ⅱ 2 superimposed unit. Located in the north-central part of the fault buried hill structural belt in the east of Liaohe River, it is 3 ~ 5 kilometers wide from east to west and 50 kilometers long from north to south, with an exploration area of 200 square kilometers.

According to the oil and gas display of the wells drilled to Mesozoic, except for Long 1, all other wells have oil and gas display in different degrees, especially Jie 3 well in the interval of 2046.4 ~ 2009.4 m, and the daily gas production of 4mm choke is 3500m3；. From April 2046 to 2028.2 m interval, the daily gas production of 38mm choke is 6290m3, and a small amount of light oil is produced, which is a Mesozoic oil and gas reservoir.

Structure and evolution characteristics of (1)

Sanjiebao-Qinglongtai fault anticline belt * * * consists of five high points, with a trap area of 63.8 km2, a closure of 500m, a buried depth of 3 100m (Figure 6-2-20, Figure 6-2-2 1, Table 6-2-24) and shallow strata.

Sanjiebao-Qinglongtai fault anticline belt began to develop in Paleogene, and Dongying period was its main formation period.

(2) Characteristics of source rocks, reservoirs and caprocks

The dark mudstone of the Mesozoic Lishugou Formation is relatively thin at the top of Sanjiebao-Qinglongtai fault structure belt, with a thickness of 100 ~ 200m, and is about 600m near the Fangshenpao structure, and the cumulative thickness can account for more than 80% of this layer. According to the analysis of Wang Shen 1 well, the source rock of lishugou formation is I-II 1 kerogen.

The reservoirs are mainly sandstone reservoirs of Lishugou Formation, volcanic reservoirs of Xiaoling Formation and Ordovician limestone reservoirs. Among them, the sandstone reservoir of Lishugou Formation is the main oil-gas bearing reservoir, and the cumulative thickness of sandstone is generally between 20-90m, and the thickness of single layer is generally between 0.5-5m. Well Jie 3 encountered Ordovician, lacked Carboniferous-Permian and developed karst caves. According to the core physical properties analysis of Ordovician Majiagou limestone 1 9 block in Wang Shen1Well, the porosity is 2.8% ~ 7.4%, with an average of 4.43%, and the minimum permeability is 1× 10-3μm2, generally (3 ~ 9 )×/.

There are two types of caprocks: mudstone and volcanic rocks. Well Jie 3 reveals that the Jurassic Xiaodonggou Formation is red silty mudstone and argillaceous siltstone with a thickness of 323 meters, which directly covers the Ordovician. The upper part is the Lower Cretaceous Lishugou Formation, which is dominated by lacustrine dark mudstone. Well Jie 3, with a drilling thickness of 207 meters, is the main source rock and good caprock in the eastern depression.

(3) accumulation

Oil and gas reservoirs are controlled by structures, which are fault blocks and fault anticlines. In the high part of the structure, rocks are easily broken and fractures are developed, which can form the enrichment zone of oil and gas reservoirs. Because the structure was formed earlier, Cenozoic is the main hydrocarbon generation and accumulation period, and well Jie 3, located in the lower part of the belt, produces oil, indicating that the Mesozoic oil and gas reservoir conditions are good. It belongs to Ⅱ 2 superimposed primary reservoir-forming model.

(4) lateral plugging

Mesozoic hydrocarbon source conditions, reservoir conditions and sealing conditions are all good, and the lateral sealing of faults determines the effectiveness of traps.

(5) the number of resources

The oil resources estimated by trap method are 2590.3× 104t.

2. Yannan structural belt

It belongs to the strategic area of the eastern sag of Liaohe River, and it is a Ⅱ 2 superimposed unit. It is located near the 5m water depth line in the eastern sea area of Kuihuadao Oilfield in the eastern depression of Liaohai, with an exploration area of about 200km2.

Figure 6-2-20 Structural Map of Ordovician Top in Sanjiebao Area

(According to Liaohe Oilfield, 2002)

Figure 6-2-2 1 Reservoir-forming Model in Sanjiebao Area

Table 6-2-24 Comprehensive Evaluation Table of Traps in Sanjiebao-Qinglongtai Area

(According to Feng Nianzhong 1988)

At present, three wells have been drilled, namely Yannan 1, 2, 10 1. Among them, Yannan 1 and 2 all have fluorescence or oil traces in Guantao Formation, Mesozoic and Paleozoic, and heavy oil reservoirs are obtained in Guantao Formation, which has great exploration potential (Table 6-2-25

Table 6-2-25 Drilling Stratification Data Sheet in Yannan Area Unit: m

(According to Liaohe Oilfield Exploration and Development Research Institute)

Structure and evolution characteristics of (1)

Yannan structural belt is a horst belt sandwiched between Yannan fault and Yandong fault (Figure 6-2-22, Figure 6-2-23). The overall shape of the basement is high in the north and low in the south, high in the east and low in the west, with many beaded nose mounds. Among them, Beishantou has the largest scale, the shallowest burial depth and complete shape; Nanshantou, on the other hand, is small in scale, deeply buried, cut by many secondary faults and complicated in shape. Four compound traps are developed from south to north, and traps No.3 and No.4 have not been drilled (Table 6-2-26).

Fig. 6-2-22 Interpretation Profile of Seismic Line in Yannan Area 1020

(According to Liaohe Oilfield, 2002)

Yannan structural belt began to develop from Paleogene, and there were few Cenozoic deposits at the top of the structure, which was an inherited uplift.

(2) Characteristics of source rocks, reservoirs and caprocks

The source rocks are mainly dark mudstone of Mesozoic Lishugou Formation, which is widely distributed, thick and rich in organic matter, and the hydrocarbon generation intensity is more than 200× 104t/km2. Reservoirs include clastic rocks of Guantao Formation, Mesozoic volcanic rocks and Paleozoic limestone. Mesozoic volcanic rocks are dominated by andesite with undeveloped fractures, while Paleozoic carbonate reservoirs have good physical properties. According to the core observation of yannan 1 well, there are many large fractures with a width of 1 ~ 3 mm and a length of 5 ~ 10 cm, and small fractures are common. The Mesozoic large set of igneous rocks is dense, which can effectively cover the underlying oil and gas and become a good cover for Paleozoic carbonate rocks in this area.

(3) accumulation

The structure was formed earlier, and the main hydrocarbon generation period and reservoir formation period were Cenozoic, belonging to ⅱ 2 superimposed primary hydrocarbon generation and reservoir formation model.

(4) Key factors: hydrocarbon generation conditions.

Because of the integrity of traps and the late accumulation period, hydrocarbon generation conditions have become the main controlling factors of oil and gas enrichment. The hydrocarbon generation intensity in this area is (100 ~ 200) ×104 t/km2, but the area of hydrocarbon generation center is small, and the hydrocarbon supply conditions determine the enrichment degree in this area.

(5) the number of resources

The oil resources estimated by trap method are 2732.4× 104t.

Figure 6-2-23 Structural Map of Mesozoic in Yannan Area

Table 6-2-26 Table of Trap Elements and Resources

(According to Liaohe Oilfield)