Maoming Yang Jiao fortune-telling

Resource evaluation of Maoming oil shale mining area

Maoming Basin is one of the most famous oil shale producing areas in China, which is located in the west of Guangdong Province, spanning three counties and one city, starting from Gaozhou in the north, reaching Maoming House in the south, bordering Huazhou in the west and Dianbaiyaojiao in the east. It is bounded by Paleogene outcrop line in the southwest and Gaopengling fault in the northeast. The strike is 44km long, 4 ~14 km wide and covers an area of about 400km2. Geographical coordinates are: east longitude11038 ′ ~1100 ′, north latitude 2140 ′ ~ 2154 ′. The mountains around the basin are mainly denuded, and the landform is hilly and mountainous. Convenient transportation, developed railways and highways, good economic and geographical conditions and complete water and electricity supply. There are three oil shale areas in the basin, namely Maoming oil shale area, Dianbai oil shale area and Gaozhou oil shale area.

Figure 8- 19 Oil-bearing contour map of rich ore beds in Fushun mining area

(1) Overview of exploration and development

The exploration of oil shale and coal in Maoming Basin began in the early 20th century. During the period of 1905 ~ 1924, China people and foreigners conducted geological exploration for Maoming Jintang oil shale, and 7 exploratory wells were drilled. In the 1920s, the Japanese took two sacks of oil shale samples back to Japan for analysis. 1926, Zhou Siming, the former Guangdong Provincial Department of Industry, conducted exploration, drilled 12 exploratory well, and conducted low-temperature dry distillation analysis on samples, but the measured data and information were stolen by the Japanese. Before 193 1 year and 1948, Wang Shenping of Guangdong-Guangxi Geological Survey and Chen, a former professor of National Sun Yat-sen University, conducted detailed surveys in this area respectively. The formal large-scale exploration of oil shale in Maoming Basin mainly started at 1954. Oil shale and coal in Maoming Basin were successively explored by Central South Coalfield Geological Exploration Bureau 130 Team, Zhanjiang Geological Team 5, Dianbai County Geological Team and Maoming Petrochemical Oil Shale Company. At first it was mainly for coal exploration. With the discovery of oil shale, it gradually turned to oil shale exploration until 1979. Completed a lot of physical workload such as mechanical coring drilling, manual drilling, trench exploration, shallow well and hydrological drilling. The exploration degree of oil shale in Youganwo Formation in Jintang Mining Area, Yang Jiao Mining Area, Low Mountain Mining Area and Shigu Mining Area has reached the level of detailed investigation, and the exploration degree of oil shale in Shangcun Formation has reached the level of detailed investigation.

The development and utilization of oil shale in Maoming Basin has a long history. Before the founding of New China, local people had excavated shallow oil shale for domestic fuel. 1955 the central government decided to build a large shale oil plant in Maoming, 1970 designed the fourth boiler (the famous Maoming Garden Boiler), with an annual refining capacity of 19× 104t, and by the end of 1992. The main reasons for the shutdown of oil shale refining are low oil content, high water content, low oil yield, high energy consumption and high wages. The actual refining cost is 850 yuan per ton, while the price of crude oil is about 640 yuan per ton. 1990 started the construction of the fluidized bed boiler power plant, and 199 1 year started to generate electricity and gas, with an annual maximum power generation of 90 million kwh and a steam production of 6 MW. In 2004, Guangdong Yuedian Group formally proposed a 20× 104kW Maoming oil shale circulating fluidized bed power generation project.

(2) Geological characteristics

Maoming Paleogene fault basin was formed on the basis of Nansheng Cretaceous structural basin. On the northeast side of the basin, there is a NW-trending Gaopengling fault that controls the Paleogene and Neogene deposits of the basin, and it controls the formation of Maoming fault basin. The Paleogene and Neogene strata in Maoming basin strike northwest and tend to northeast, that is, the closer they are to Gaopengling fault, the greater the subsidence amplitude, and the profile is dustpan-shaped, that is, monoclinal structure.

The main fault structures are NW-trending faults, NE-trending faults, EW-trending faults and NS-trending faults. Among them, NW-trending faults play an important role in controlling the formation of the basin, with Gaopengling fault (F 12) as the main fault, and Heshan fault (F8), Beitou fault (F4) and Chen Dong fault (F5) in the northeast, and Jintang fault (F 18) and Jintang fault in the mining area or exploration area. Gaopengling fault (F 12) is the main fault that controls the development of the basin in this area. Jintang fault (F 18) and xinxu buried fault (F 19) are normal faults, which have certain destructive effects on oil shale deposits. The NE-trending faults, EW-trending faults and NS-trending faults have little effect on the formation and control of oil shale.

Sinian, Cretaceous, Paleogene and Neogene strata are exposed in the basin. The main strata in the basin are Paleogene and Neogene, which are well developed and divided into Shangdong Formation, Youganwo Formation, Huangniuling Formation, Shangcun Formation, Laohuling Formation and Gaopengling Formation from bottom to top. Youganwo Formation (E2-3y) is the main ore-bearing stratum of Maoming oil shale, mainly composed of brown-black oil shale, with 1 ~ 3 layers of lignite, clay, fine sandstone and siltstone locally. There is a 50 cm thick breccia at the bottom, and the inferior lignite layer above this layer contains fossils of large vertebrate bones, molars, plant fragments and so on. From the analysis of molars, it should be a large herbivore. Above this layer, oil shale is rich in fossils such as Maoming turtle, turtle, crocodile and fish. Shangcun Formation (N 1sh) is another oil shale-bearing interval with simple lithology, and the upper part is gray claystone, oil-bearing claystone and argillaceous siltstone. The middle part is low oil content shale and oil shale mixed with calcareous siltstone and lignite layer; The lower part is organic claystone mixed with siltstone and fine sandstone, and kaolin ore is also produced in some areas, and pyrite microcrystals can be seen in each layer. The thickness of this formation is 354 ~ 473 meters, which is in integral contact with the underlying Huangniuling Formation.

(3) Metallogenic geological conditions

The genetic types of oil shale and coal seam deposits in this area are semi-deep lake-deep lake sedimentary type and lake sedimentary type respectively. Tectonic activity and sedimentation are the main controlling factors of oil shale mineralization. Therefore, by analyzing the characteristics of tectonic activity in different periods and stages, as well as the relationship between paleogeographic environment, sedimentation and sedimentary construction characteristics related to tectonic activity and mineralization, the temporal and spatial distribution law of oil shale is summarized, and at the same time, the basis for metallogenic prediction is provided.

1. Structural conditions

According to the relationship between tectonic activity characteristics and mineralization, oil shale, coal and kaolin in the basin can be divided into the following three tectonic-sedimentary metallogenic periods: Eocene-Oligocene tectonic-sedimentary oil shale and coal metallogenic period. Neogene Miocene tectonic sedimentary kaolin mineralization period and Pliocene tectonic sedimentary kaolin mineralization period. Especially the Eocene-Oligocene tectonic sedimentary cycle plays a decisive role in the formation of oil shale and coal in this area.

In Paleogene and Neogene, Himalayan movement affected this area, Gaopengling fault continued to move, and the footwall of the fault slipped, which controlled the basic form of Cenozoic sedimentary basin and its northeast sedimentary boundary. Due to the uneven subsidence amplitude in different sections of the basin, the subsidence amplitude in the north near Gaopengling fault is much larger than that in the south of the basin, and the maximum subsidence amplitude is 120m, which has begun to form a dustpan profile structure. In addition, due to the undulating basement and the NW-trending secondary faults in the southwest (such as Jintang fault, Xinwei fault and Yang Jiao fault), a series of NW-trending secondary marginal depressions were formed in the southwest margin of the basin, which created a good sedimentary environment and spatial conditions for the formation of Paleogene and Neogene oil shale, coal and kaolin.

2. Sedimentary paleogeographic environment

The Eocene-Oligocene dustpan basin developed early, and the sedimentary basement was generally high in the south and low in the north. The inland lake was first formed in the north, with narrow water area and rapid shallow water flow, forming an unstable water deposition environment and accepting the deposition of terrestrial rivers, lakes and foothills. In the shallow lake swamp area of the second depression in the southwest margin of the basin, animals and plants grow vigorously, which is the main area of biological deposition. During Eocene-Oligocene, there were two sedimentary centers in Maoming Basin, which developed Shangdong Formation and Youganwo Formation, among which Youganwo Formation was the main deposit, and the sedimentary center near Gaopengling fault in the northeast was influenced by Gaopengling fault, and the other was mainly influenced by the paleotopography of Nansheng Cretaceous basin in the southwest margin of the basin. The former sedimentary center is the main sedimentary center in this period, which has the characteristics of deep burial and large thickness.

In the early Miocene, the basin developed on the original basis, and due to the further activity of Gaopengling fault, it began to accept the fluvial facies and lakeside facies terrigenous clastic deposits of Huangniuling Formation. With the intensification of subsidence, a shallow-deep lake environment was formed in the late Miocene. During this period, the climate was warm and humid, the water flow was stable, the lake basin was stable, and the lake surface was open, mainly algae, freshwater snails and mussels, and the lake basin received a lot of argillaceous debris and organic matter deposition. In Miocene, the magnitude and speed of crustal subsidence were relatively large, with the maximum subsidence reaching more than 800 meters and the thickness of Shangcun Formation reaching 672 meters ... However, due to the rapid sedimentation rate, relatively low biological growth and sedimentation density, and long-term exposure to the surface after diagenesis, it is not conducive to the transformation and preservation of organic matter into hydrocarbons, so the oil-forming conditions are relatively poor.

(4) Characteristics and distribution of oil shale.

1. Characteristics of oil shale

The oil shale of Youganwo Formation is yellowish brown and black. After long-term sun exposure, its surface is brown or brown-white, and its hardness is small, so it can be scratched with nails. Oil shale slices can be lit or smoked with a lighter, which has an oily smell. Generally speaking, the darker the color, the better the texture, the lighter the specific gravity and the better the quality.

The highest oil content in the sample is 1 1.07%, and the highest oil content in the whole layer is 7.55%, with an average of 6.22%. The maximum weight is 2. 15t/m3, with an average of 2.007t/m3；; ; The maximum calorific value is 9.90MJ/kg and the average calorific value is 6.90 mj/kg. The highest sulfur content is 2.07%, and the average sulfur content is 1. 14%.

The thickness of oil shale is generally 2.05-33.0 1m, with an average of 22.75m, with the thickest being 33.0 1m in hole H22 and the thinnest being 2.05m in hole 3904. The oil content of oil shale in Shangcun Formation is generally 4.02% ~ 5. 12%, with an average of 4.58%. The highest oil content of hole 3306 is 5. 12%, and the lowest oil content of hole W 50ZA is 4.02%.

2. Distribution law of oil shale

Oil shale and lignite in the mining area are mainly produced in Youganwo Formation. Industrial seams are strictly controlled by Youganwo Formation, but the spatial distribution of ore belts is controlled by Jintang fault, Xinwei fault and Yang Jiao fault in the southwest margin of the basin, and the ore belts are distributed in NW-SE direction, followed by Gaozhou, Maoming and Dianbai ore-bearing areas. The spatial distribution of each ore-bearing area or exploration area is consistent with the corresponding secondary sag (Figure 8-20).

Figure 8-20 Section of Line 43 in Jintang Exploration Area, Maoming Mining Area, Guangdong Province

From the contour map of oil shale thickness of Youganwo Formation in Maoming Basin, it can be seen that the thickness of Maoming oil shale is generally 4 ~ 38m, with an average of about 20m, which is characterized by a large thickness at the gentle slope of the southwest margin of the basin and a thin thickness at the middle of the basin-controlling fault in the northeast. There are three thick areas on the gentle slope of the southwest margin, corresponding to three secondary depressions, and there are also two thick areas on the basin-controlling fault in the northeast. There are two places where the thickness of oil shale is locally thinner on Line 38 and Line 4 1. There is an east-west low-thickness area near Well 3 105, which extends northward to Well Zk2307 and is buried to a depth of 600 meters (Attached Figure 8-2 1).

Figure 8-2 1 Oil shale thickness contour map of Youganwo Formation in Maoming Basin

(v) Evaluation of oil shale resources

According to the new evaluation standard of oil shale, the oil shale resources in Maoming Basin are evaluated. The oil shale resources are 1 648 876× 104t, of which the proven oil shale resources are 680 030× 104t, and the technically recoverable oil shale resources are 830 807× 104t, among which the proven oil shale is. There are shale oil resources in the mining area100053x104t, of which shale oil exploration resources are 4 1× 104t, and shale oil technical recoverable resources are 50 26 1× 104t, of which shale oil exploration resources are 365438. The recoverable resources of shale oil in the mining area are 37 128× 104t, of which the recoverable resources of shale oil are 22,934×104t.

According to the new oil shale evaluation standard, the predicted oil shale resources in Maoming Basin are 968 846× 104t, of which the potential oil shale resources are 968 846× 104t and 365 438+365 438+04 875×104t. Potential oil shale resources. The potential shale oil resources are 58 232× 104t, the potential technically recoverable resources are 18 925× 104t, and the potential recoverable resources are14194×104t.

In the actual prediction process, according to the area between two isolines on the oil shale thickness isoline map, the predicted area of oil shale in Youganwo Formation is calculated in blocks. Oil content takes the average oil content of exploration areas in Maoming, Dianbai and Gaozhou mining areas. The weight is selected in a similar way; The thickness of oil shale in this block is the average of two thickness isolines; Then use the volumetric method to calculate the reserves.