KR101602808B1 - Method for investigating of submarine sementary layers - Google Patents

Abstract

A submarine sediment layer investigation method is disclosed. (A1) selecting an area to be surveyed of a marine adjacent to the land and obtaining seismic data for the sub-sea sediments of the survey area using the seismic wave method; (b1) obtaining the actual survey data for the onshore outcrops by actually surveying the inclination and inclination of the onshore outcrops of the sediment layer to be surveyed in at least one area of the land; (c1) enlarging the actual survey data by extrapolation until at least the area to be surveyed is reached to obtain enlarged data on the land off-road; And (d1) comparing the expansion data with respect to the onshore outcrop to the seismic data to determine a layer on the seismic data having a slope characteristic that is closest to the expansion data on the onshore outcrop as a layer corresponding to the layer to be surveyed Step.

Description

METHOD FOR INVESTIGATION OF SUBMARINE SEMENTARY LAYERS [0002]

The present invention relates to a method of irradiating a submarine sedimentary layer, and more particularly, to a method of irradiating a submarine sedimentary layer to find a submarine sedimentary layer usable as a carbon dioxide disposal site.

As is well known, a sedimentary layer is a layer formed by depositing inorganic substances originating in soil or rocks or organic matter originating from living organisms by water, wind, glaciers and the like.

Deposits occur not only on land but also on the seabed. The sedimentary materials underlying the subsoil deposits originate from land, and generally submarine sediments are developed predominantly near the coast.

These subsea sediments are also used as a place to dispose of industrial waste originating from industrial activities. For example, submarine sediments can be used as a place to store waste gas, such as carbon dioxide, which is considered to be the main cause of greenhouse gas emissions.

1, which illustrates an example in which the submarine sediment layer is used as a carbon dioxide disposal site, will be described in more detail.

As shown in FIG. 1, carbon dioxide can be disposed of in the storage layer by injecting carbon dioxide, which is supplied from a submarine sediment layer to a storage sediment layer, and injecting liquefied carbon dioxide through the injection pipe. In this case, sediments with high porosity and high permeability can be used as storage layers for storage of large amounts of carbon dioxide in the various sedimentary layers. Especially, the regions (dome) developed in the form of dome so that the supplied carbon dioxide does not escape to the outside Dome area) are suitable as carbon dioxide disposal sites. As an additional requirement, it is required that there is an impervious layer directly above the storage layer for storage so that injected carbon dioxide does not escape upward.

Therefore, in order to inject carbon dioxide into a subsea sediment layer and dispose of it, a storage sediment layer with a dome-shaped area must be found in advance, with the impervious layer located on the upper side. This storage sediment exploration can be performed by seawing several candidate areas that are predicted to have a dome - like topography by the seismic exploration method.

However, according to the exploration method which depends only on the seismic data, since it is not recognized whether there is a sedimentary layer or an impervious layer for storage and drilling is carried out, There is a disadvantage in that the drilling operation must be frequently performed as long as it is not found, and there is a disadvantage in that it is difficult to predict in advance to what extent the drilling operation should proceed.

Therefore, it is difficult to increase the efficiency and accuracy of the survey by using the surveying method which depends only on the seismic data. Therefore, it is difficult to avoid a lot of expense and effort in the exploration.

Accordingly, it is an object of the present invention to provide a method for exploring a sedimentary layer existing in the sea bed, which can increase the efficiency and accuracy of exploration compared to existing exploration methods.

In order to accomplish the above object, the present invention provides a method of detecting seawater, comprising the steps of: (a1) selecting an area to be surveyed of an ocean adjacent to a land and obtaining seismic data for seafloor sediments of the area to be surveyed by using a seismic wave method; (b1) obtaining the actual survey data for the onshore outcrops by actually surveying the inclination and inclination of the onshore outcrops of the sediment layer to be surveyed in at least one area of the land; (c1) enlarging the actual survey data by extrapolation until at least the area to be surveyed is reached to obtain enlarged data on the land off-road; And (d1) comparing the expansion data of the onshore outcrop with the seismic data to determine the layer on the seismic data indicating the geological characteristic most closely matching the expansion data on the onshore outcrop to the layer corresponding to the layer to be surveyed The method comprising the steps of:

The deposition target layer may be a deposition layer for storing carbon dioxide. In this case, the submarine sedimentary layer irradiating method may include the steps of: (e1) acquiring coordinates of a dome-type area in the seismic wave data for the stratum determined to correspond to the sediment layer to be irradiated and performing drilling at the acquired coordinates, And verifying the presence or absence of the target deposit layer. In this case, the method further comprises the step of (d2) calculating an expected depth of the stratum determined to correspond to the investigation target sediment layer using the average velocity of the seismic waves calculated from the enlargement data on the land overhang In step (e1), the drilling is preferably performed using the estimated depth calculated in step (d2).

The extrapolation performed in the step (c1) may be performed along the slanting direction of the onshore outcrops of the sediment layer to be surveyed obtained in the step (a1).

The step (a1) may be performed before the step (b1), or may be performed between the step (c1) and the step (d1).

According to the method of irradiating the submarine sedimentary layer according to the present invention, prior to drilling to find a submarine sedimentary layer suitable for use as a sedimentary layer for storage, The efficiency and accuracy of the drilling operation can be increased compared with the case where the drilling operation is performed with only the elastic wave data, and accordingly, the cost and effort for exploration for the sediment layer for storage can be increased Can be greatly reduced.

According to the method for surveying the submarine sedimentary layer according to the present invention, before proceeding with drilling to find a submarine sedimentary layer suitable for use as a storage sedimentary layer, It is possible to calculate and utilize the estimated depth of the corresponding stratum. In this case, since the depth to the dome-shaped region existing in the storage sediment layer is predicted, the drilling operation can be more planned, .

1 is a schematic cross-sectional view showing an example in which a submarine sediment layer is used as a carbon dioxide disposal site.
2 is a flowchart showing an embodiment of a method of irradiating a submarine sedimentary layer according to the present invention.
3 is a view schematically showing an example of a region to be surveyed to which the embodiment of FIG. 2 can be applied.
FIG. 4 is a schematic view showing an example of an acoustic wave data obtained by applying the seismic wave method in the survey area shown in FIG.
5 is a schematic view showing a cross section along the X direction in the terrain shown in Fig.
FIG. 6 is a schematic view showing an example of an isocenter topographic map of a specific stratum (stratum corresponding to a sediment layer to be irradiated) extracted from the seismic wave data illustrated in FIG.

The method of irradiating the submarine sedimentary layer according to the present invention can be applied not only for irradiating a storage sedimentary layer which can be discarded by injecting carbon dioxide but also for investigating other kinds of sedimentary layers. Therefore, in the case of the embodiment illustrated below, it is specified that the deposit layer for storing carbon dioxide is a sediment layer to be irradiated. However, the submerged sediment layer irradiating method according to the present invention can be similarly applied to irradiate other kinds of sediment layers.

FIG. 2 is a flow chart showing an embodiment of a method of irradiating a submarine sedimentary layer according to the present invention, FIG. 3 is a view schematically showing an example of a region to be surveyed to which the embodiment of FIG. 2 can be applied, FIG. 5 is a schematic view showing a cross section of the terrain of FIG. 3 along the X direction. FIG. 5 is a schematic view showing an example of the seismic wave data obtained by applying the seismic wave method in the region to be surveyed.

An embodiment of the submarine sediment layer irradiating method described in Fig. 2 will be described with reference to Figs. 3 to 5. Fig.

First, in step S10, an area to be surveyed is selected from adjacent areas of the land, and seismic data of the sub-sea sediments of the area to be surveyed are obtained using the seismic wave method. The step S10 will be described in more detail as follows.

It is desirable to select an area in which the sediments are developed on the coast adjacent to the land and the outcrop of the sediments is developed on the land. Here, the outcrop means that rocks and strata are not covered by soil, but are exposed directly to the surface of the earth. In the case of Korea, Yeongil Bay, which is suitable for such an exploration target area, is located in the nearby land. FIG. 3 schematically shows the outcrop region O on the land where the outcrops of the exploration target area S and the sediment layers of the exploration target area S are selected from terrain similar to Youngil Bay.

The seismic wave method refers to a method of determining the geological structure by analyzing the time and waveform of reflected waves or refraction waves that are generated by seismic waves artificially on the surface or sea. By applying this seismic wave detection method to the area S to be surveyed in FIG. 3, it is possible to obtain the elastic wave data for the area S to be surveyed.

Fig. 4 shows the seismic data obtained in the area S to be surveyed. More precisely, Fig. 4 shows cross-sectional data along the X direction in Fig. 3 extracted from the seismic data. A plurality of stratigraphic horizons B1, B2, B3, B4, B5, B6 and B7 shown in FIG. 4 correspond to a plurality of actual deposit layers A1, A2, A3, A4, A5, A6, A7). The types and depths of the actual deposit layers A1, A2, A3, A4, A5, A6, and A7 of FIG. 5 can be determined from the layer bases B1, B2, B3, B4, B5, B6, There is no number. It should be noted that the outline of the actual deposited layers A1, A2, A3, A4, A5, A6, A7 corresponding thereto from the layer bases B1, B2, B3, B4, B5, B6, And thickness can be grasped.

Next, in step S20, actual incidence data of the onshore outcrops are obtained by examining the inclination and inclination of the onshore outcrops of the sediment layer (storage sediment layer) to be surveyed in at least one region of the land. Step S20 will be described in more detail as follows.

As mentioned above, in this embodiment, the deposit to be investigated is a deposit layer for storing carbon dioxide. Referring to FIG. 5, it is assumed that the fifth deposited layer A5 from the top is a sediment layer usable for storing such carbon dioxide. Therefore, the A5 layer as a storage layer is a layer having a high porosity and a permeability suitable for the storage of carbon dioxide. Immediately above the A5 layer, it is assumed that there is an A4 layer which is an impervious layer.

As shown in FIG. 5, there may be an outcrop region in the land including an outcrop exposed on the ground surface of the A5 layer as a sediment layer to be surveyed. In Figs. 3 and 5, an outcrop region O in which such a five-layer onshore outcrop is present is exemplarily shown. In step S20, actual survey data showing the geological characteristics of the onshore outcrops are obtained by examining the strike and dip of the onshore outcrop of the A5 layer existing in the outcrop region (O). The X direction shown in Figs. 3 to 5 indicates the inclination direction of the A5 layer irradiated from the outermost region (O). In this specification, the oblique direction is defined as meaning the direction of the horizontal component of a dip of a certain deposited layer.

Referring to FIG. 5, there is an outcrop for the storage layer (A5 layer) in the outcrop region, and an outcrop for the impervious layer (A4 layer) immediately thereon. Therefore, by examining the outcrops of the sediments in the outcropping area (O), it can be seen that the impermeable layer (A4 layer) and the storage sediment layer (A5 layer) arranged up and down are developed along the X direction to the area Can be predicted.

Next, in step S30, the actual survey data on the onshore outcrops of the deposit layer (A5 layer) to be surveyed obtained in step S20 is extrapolated to the survey area S at least along the oblique direction (X direction) (estimated data) for the onshore outcrop of the sediment layer (A5 layer) to be surveyed is obtained by extrapolation by extrapolation. Step S30 will be described in more detail as follows.

In step S30, the inclination data of the land layer of the storage sediment layer (A5 layer) obtained in the previous step S20 is extrapolated to the area where the exploration target area S starts or at least partially overlapped with the exploration target area S . In the case of this embodiment, it is exemplified that only the region where the region S to be surveyed starts is performed. In this case, as shown in Figs. 3 and 5, the region between the outcrop region O and the region to be surveyed S is extrapolated Area (E).

The extrapolation method applied in step S30 is a known numerical method for calculating the estimated data in the section where the actual data can not be grasped based on the actually grasped data. Therefore, the expanded data for the storage sediment layer (A5 layer) obtained in step S30 means the estimated data in the extrapolated area (E) estimated from the actual data of the onshore outcrops. In this embodiment, the estimation data for the inclination of the storage layer (A5 layer) is calculated in the extrapolation area (E) by extrapolation based on the slope data for the terrestrial outcrops obtained in the outcrop region (O). Therefore, although it is not possible to obtain the actual slope data for the A5 layer as the sediment layer to be surveyed in the extrapolation area (E), it is possible to estimate the slope change of the A5 layer located in the extrapolation area (E) can do.

Next, in step S40, the enlarged data (estimated tilt data) for the terrestrial outcrop obtained in the previous step S30 is compared with the seismic data of FIG. 4 obtained in the previous step S10. As a result of the comparison, the stratigraphic layer on the seismic data, which indicates the geologic characteristics most closely matching the extensional data for the offshore outcrops, is determined as the stratum corresponding to the sediment layer (A5 layer). Step S40 will be described in more detail as follows.

B2, B3, B4, B5, B6, and B7 can not be determined from the seismic wave data shown in FIG. 4 for which layer layers B1, B2, B3, B4, ) Indicate which geological features (inclinations and slopes) are present in the area (S) to be surveyed. Therefore, it is possible to compare the gradient data showing each layer (B1, B2, B3, B4, B5, B6, B7) with the estimation data in the extrapolation area (E) obtained in the previous step S30, The layer line representing the geological characteristic (for example, slope) most closely matching with the layer to be irradiated is determined as the layer layer corresponding to the layer to be irradiated (layer A5). In the case of this embodiment, it is assumed that the layer B5 disposed at the fifth position from the top of the elastic wave data of FIG. 4 is a layer boundary corresponding to the deposition target layer (layer A5).

As described above, according to the method of irradiating the submarine sedimentary layer according to the present embodiment, it is possible to determine, at the time when the step S40 is completed, the layer to be surveyed (A5 layer) exposed on the land by the onshore outcrops corresponds to which layer on the seismic wave data.

Next, in step S50, the average velocity of the seismic waves is calculated from the expanded data (estimated tilt data) for the onshore outcrop obtained in the previous step S30. Then, in step S40, the predicted depth of the layered line B5 determined as the layered line corresponding to the layer to be irradiated (layer A5) is calculated using the calculated average speed. Step S50 will be described in more detail as follows.

5, the actual depth d of the deposition target layer (layer A5) can not be known at the boundary (X = X1) between the extrapolation area E and the exploration target area S, The estimated depth d 'of the layer to be surveyed (layer A5) can be calculated at the boundary (X = X1) between the extrapolated area E and the exploration target area S from the estimated inclination data. Referring to FIG. 4, in step S40, it is determined that a seismic wave reaches the layer B5 at the boundary (X = X1) with respect to the layer B5 determined to correspond to the layer A5 to be irradiated (Or the time it takes for the seismic wave to return from the stratum) Δt can be obtained. Therefore, the estimated average velocity Vmin (= d '/ t) of the seismic waves can be calculated when the seismic wave propagates to the target sedimentary layer (layer A5) with the estimated depth d' and the required time t.

Next, in step S60, the coordinates of the dome-shaped area are obtained from the elastic wave data for the layer B5 determined to correspond to the layer to be irradiated (layer A5) in the previous step S40, The drilling is performed using the estimated depth calculated in step S50 to verify the existence of the sediment layer (A5 layer) to be surveyed. Step S60 will be described in more detail as follows.

From the seismic wave data obtained in the step S10, it is possible to extract the topographic map of the bedrock (B5) identified as corresponding to the bedding layer (layer A5) to be surveyed in the step S40. Fig. 6 is a schematic view showing an example of such a beak topography map. As shown in Fig. 6, the topographic map for the layer B5 in the area S to be surveyed may include a dome-shaped area having a convex shape. Of course, there may not be such a dome-shaped region, and even if there is a storage layer (A5 layer) in the exploration target area S, the deposit layer can not be used for waste gas storage.

On the other hand, if it is determined that there is more than one dome-shaped area as a result of the analysis of the topography of the canopy (B5), it can be seen that at the coordinate point of the dome- ), The drilling is carried out to the depth of approximately the depth, and it is verified whether or not the sediment layer (A5 layer) to be investigated is actually located at the coordinate point. As a result of the verification, if the sediment layer (A5 layer) to be surveyed is actually located at the coordinate point, an injection pipe as shown in Fig. 1 is buried in the borehole used at the time of verification to inject carbon dioxide into the deposit layer (A5 layer) can be utilized as the carbon dioxide waste layer.

In the case of this embodiment, the estimated depth calculated in step S50 is utilized in step S60. If the estimated depth is used, although the estimated depth is based on the above-described estimated depth d ', there may be an error. However, even if the error is taken into account, The drilling operation can be carried out with a plan (prediction) on whether or not the drilling is to be carried out. However, in alternative alternative embodiments, step S60 may be performed without utilizing the expected depth. In this alternative embodiment, although the efficiency of the drilling operation is relatively reduced, it is not impossible to verify the sediment layer (A5 layer) to be surveyed through drilling. In this alternative embodiment, since the expected depth is not utilized, step S50 of calculating the expected depth is omitted.

In the case of the submarine sediment layer surveying method according to the embodiment of FIG. 2 described above, the step S10 for obtaining the seismic wave data through the seismic wave surveying method is performed before the step S20 for examining the incline and inclination of the land off- do. Alternatively, step S10 may be performed between step S30 for obtaining the estimated data magnified by extrapolation and step S40 for comparing the extrapolated data and the acoustic wave data to determine the layered level matching the extrapolated data.

In the embodiment of FIG. 2 described above, the gas to be decomposed is limited to carbon dioxide. However, the method for irradiating the submarine sediment layer according to the present invention is not limited thereto. For example, for the purpose of storing other waste gas that can be stored in the submarine sediment layer The same can be applied.

According to the method for irradiating the submarine sedimentary layer according to the present invention, as described above, before proceeding with drilling to find a submarine sedimentary layer suitable for use as a storage sedimentary layer, It is possible to determine which layer of the seismic data corresponds to the sedimentary layer for storage, so that the efficiency and accuracy of the drilling operation can be increased compared to the case where the seismic work is performed only with the elastic wave material, This can significantly reduce the cost and effort of exploration for the seabed.

According to the method for surveying the submarine sedimentary layer according to the present invention, before proceeding with drilling to find a submarine sedimentary layer suitable for use as a storage sedimentary layer, It is possible to calculate and utilize the estimated depth of the corresponding stratum. In this case, since the depth to the dome-shaped region existing in the storage sediment layer is predicted, the drilling operation can be more planned, .

S: Area to be explored
O: Outer area
E: extrapolated region
X: Direction of inclination of the sediment layer to be surveyed
A1 ~ A7: Actual seabed deposits in the exploration area
B1 to B7: Levels on seismic data

Claims (6)

(a1) selecting an area to be surveyed adjacent to the land and obtaining seismic data for the sub-sea sediments of the area to be surveyed using the seismic wave method;
(b1) obtaining the actual survey data for the onshore outcrops by investigating the inclination and inclination of the onshore outcrops of the target sediment layer in at least one region of the land;
(c1) enlarging the actual survey data by extrapolation until at least the area to be surveyed is reached to obtain enlarged data on the land off-road;
(d1) comparing a magnified data on the onshore outcrop with the seismic data, and comparing the stratum on the seismic data showing the geologic characteristics most closely matching the magnified data on the on- And obtains the time information required to reach the layer B5 at which the seismic waves are determined from the seismic waves at the boundary between the region expanded by the extrapolation method and the region to be surveyed, ), Calculating an average velocity of the elastic waves according to the estimated depth and the required time, And
(d2) calculating an expected depth of the stratum determined to correspond to the investigation target sediment layer using the calculated average velocity of the seismic waves.
The method according to claim 1,
Wherein the sediment layer to be irradiated is a sediment layer for storing carbon dioxide.
3. The method of claim 2,
(e1) acquiring coordinates of a dome-shaped area in the seismic wave data for the layered line determined to correspond to the layer to be investigated, and performing drilling at the obtained coordinates to verify presence of the layer to be investigated Further comprising the steps of:
The method of claim 3,
Wherein the drilling is performed using the estimated depth calculated in the step (d2).
The method according to claim 1,
Wherein the extrapolation performed in the step (c1) is performed along a slanting direction of the land overhang of the sediment layer to be irradiated obtained in the step (a1).
The method according to claim 1,
Wherein the step (a1) is performed before the step (b1) or between the step (c1) and the step (d1).

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