Deep sea water channel seepage barrier cause type division method

Abstract

The invention relates to a deep sea water channel seepage barrier cause type division method, and belongs to the technical field of oil-gas field development geological exploration. The invention discloses a deep sea water channel seepage barrier cause type division method. The method comprises the steps that the deposition process, the scale, the lithology, the distribution position and the gravity flow cause type of a deep sea water channel are obtained; based on the gravity flow cause type of the deep sea water channel, the seepage barrier cause type of the deep sea water channel is divided into a slump cause seepage barrier, a debris flow cause seepage barrier, a low-density turbidite cause seepage barrier and a semi-ocean deposition cause seepage barrier; and further finely dividing the cause type of the seepage barrier by combining the lithology, the scale, the distribution position and the deposition process of the seepage barrier. According to the method, the blank of a deep sea water channel internal seepage barrier cause type division scheme is filled up, so that important geological basis and guidance are provided for evaluation of internal continuity and connectivity of a deep sea water channel reservoir.

Description

Technical Field

[0001] The invention relates to a method for classifying genesis types of deep-sea water channel seepage barriers, and belongs to the technical field of oil and gas field development geological exploration. Background Art

[0002] Deepwater channels are the main channels and deposition sites for deep-sea sediment transportation. As important oil and gas reservoirs in deepwater basins, they are also the focus of current deepwater oil and gas exploration and development. However, affected by factors such as tectonic movement, sea level rise and fall, material supply, and climatic conditions, the geometric morphology of deepwater channel sand bodies is complex and changeable, and the rock phase filling types are variable. Although such reservoirs usually have good porosity and permeability, their internal structures are complex and changeable. Even within a very short lateral distance, their reservoir thickness and connectivity will vary significantly. Therefore, turbidite sandstone channel reservoirs usually have internal heterogeneities of different scales. Since it is difficult to identify small-scale heterogeneities with seismic resolution, the characterization of such underground reservoirs is still very challenging. The high permeability difference between reservoir units and non-reservoir units will have a significant impact on fluid migration during production, thus seriously restricting the efficient development of oil reservoirs. Previous researchers have done a lot of work on the structural characteristics of deepwater turbidite sandstone reservoirs, but they mainly focus on the characterization of sand bodies. The identification and connectivity of seepage barriers between sand bodies inside waterways are rarely involved. Clarifying the types of seepage barriers inside deepwater channel reservoirs is the first and key to studying the connectivity inside reservoirs. Therefore, it is urgent to invent a practical method for classifying the genetic types of seepage barriers in deepwater channels. Summary of the invention

[0003] In order to overcome the defects in the prior art, the present invention aims to provide a method for classifying the causes of seepage barriers in deep-sea channels.

[0004] The technical solution provided by the present invention to solve the above technical problems is: a method for classifying the causes of seepage barriers in deep-sea waterways, comprising the following steps:

[0005] Obtain the sedimentation process, scale, lithology, distribution location and gravity flow genesis type of deep-sea channels;

[0006] Based on the gravity flow genesis of deep-sea channels, the genesis of seepage barriers in deep-sea channels can be divided into seepage barriers caused by landslide, seepage barriers caused by debris flow, seepage barriers caused by low-density turbidite, and seepage barriers caused by semi-pelagic deposition.

[0007] Combined with the lithology, scale, distribution location and sedimentary process of the seepage barrier, the genetic types of the seepage barrier are further divided into fine categories;

[0008] The landslide-induced seepage barrier is finely divided into landslide-induced gravel-containing mudstone-induced seepage barrier and landslide-induced siltstone-induced seepage barrier;

[0009] The debris flow-induced seepage barrier is finely divided into bottom-retained mud conglomerate-induced seepage barrier, pebble mudstone-induced seepage barrier, mud debris flow-induced seepage barrier, and lateral accumulation mud conglomerate-induced seepage barrier.

[0010] The low-density turbidite-induced seepage barrier is finely divided into: layered mudstone-induced seepage barrier, lateral mudstone-induced seepage barrier, and overlying mudstone-induced seepage barrier;

[0011] The hemipelagic sedimentary origin seepage barrier is finely divided into hemipelagic drape mudstone origin seepage barrier.

[0012] A further technical solution is that the seepage barrier caused by the landslide and gravel-containing mudstone is: the lithology is mudstone and gravel-containing mudstone, 3-6m thick, 100-300m wide, distributed at the edge of the waterway, and is formed by the early overlying mudstone landslide.

[0013] A further technical solution is that the landslide siltstone-induced seepage barrier is: the rock type is siltstone, 0.5-3m thick, 10-20m wide, distributed at the edge of the waterway, and is formed by the early inner natural levee landslide.

[0014] A further technical solution is that the bottom retained mud conglomerate-induced seepage barrier is: the lithology is mud conglomerate, 1-3m thick, 10-100m wide, distributed at the bottom of the waterway or sandwiched between secondary waterway units, and is mud gravel formed by erosion at the bottom of the waterway.

[0015] A further technical solution is that the pebble mudstone-induced seepage barrier is: the lithology is pebble mudstone, 2-8m thick, 50-470m wide, distributed at the bottom of the waterway, and is an event-induced terrigenous transport deposit.

[0016] A further technical solution is that the seepage barrier caused by the muddy debris flow is: the rock type is gravel mudstone and mudstone, with a thickness of 1-10m and a width of 50-700m, distributed throughout the entire single waterway, and is eroded and filled by mud-rich debris flow.

[0017] A further technical solution is that the lateral accumulation mud gravel-induced seepage barrier is: the rock type is muddy clastic conglomerate, 0.1-2m thick, 5-60m wide, distributed between lateral accumulation secondary waterways, formed by mud gravel eroded at the edge or bottom of the waterway, and then formed by lateral accumulation.

[0018] A further technical solution is that the layered mudstone-induced seepage barrier is composed of mudstone, shale, and siltstone, with a thickness of 0.2-5 m and a width of 20-100 m, distributed between secondary waterways, and formed in the late stage of gravity flow deposition.

[0019] A further technical solution is that the lateral accumulation mudstone-induced seepage barrier is: the lithology is mudstone, 0.01-0.1m thick, 0.2-1m wide, distributed on the top of the waterway, and formed by lateral accumulation of mudstone.

[0020] A further technical solution is that the mudstone-induced seepage barrier covering the road is: the lithology is mudstone and shale, with a thickness of 0.1-1.5m and a width of >20m, distributed at the bottom and edge of the waterway.

[0021] A further technical solution is that the semi-pelagic mudstone-induced seepage barrier is: the lithology is mudstone and shale, with a thickness of 1-30m and a width of >200m, distributed on the top of a single waterway.

[0022] The present invention has the following beneficial effects: based on the filling lithofacies genetic type inside the waterway, the present invention realizes the accurate classification of the seepage barrier type inside a single waterway, fills the blank of the classification scheme of the genetic type of the seepage barrier inside the deep-sea waterway, and thus provides important geological basis and guidance for the evaluation of the internal continuity and connectivity of the deep-sea waterway reservoir. Therefore, the present invention has important guiding significance for the continuity, connectivity and reservoir exploration of the waterway reservoir in deep-water sediments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the landslide gravel-containing mudstone and the landslide siltstone of the present invention;

[0024] Figure 2 This is a schematic diagram of the example area of ​​the landslide gravel-containing mudstone of the present invention;

[0025] Figure 3 This is a schematic diagram of the example area of ​​the landslide gravel-containing mudstone of the present invention;

[0026] Figure 4 Schematic diagram of bottom retained gravel and pebbly mudstone of the present invention;

[0027] Figure 5 This is a schematic diagram of an example area of ​​bottom retained gravel according to the present invention;

[0028] Figure 6 This is a schematic diagram of the pebble mudstone example area of ​​the present invention;

[0029] Figure 7 A schematic diagram of a muddy debris flow according to the present invention;

[0030] Figure 8 It is a schematic diagram of the example area of ​​mud debris flow of the present invention;

[0031] Fig. 9 This is a schematic diagram of the lateral accumulation mud conglomerate of the present invention;

[0032] Fig.10 This is a schematic diagram of the example area of ​​lateral accumulation mud conglomerate of the present invention;

[0033] Fig.11 It is a schematic diagram of the layered mudstone of the present invention;

[0034] Fig.12 It is a schematic diagram of the layered mudstone example area of ​​the present invention;

[0035] Fig.13 This is a schematic diagram of the lateral accumulation mudstone of the present invention;

[0036] Fig.14 This is a schematic diagram of the lateral accumulation mudstone example area of ​​the present invention;

[0037] Fig.15 This is a schematic diagram of the mudstone covering the road in the present invention;

[0038] Fig.16 This is a schematic diagram of an example area of ​​mudstone covering the road in the present invention;

[0039] Fig.17 A schematic diagram of the semi-pelagic drape rock of the present invention;

[0040] Fig.18 It is a schematic diagram of the semi-pelagic drape example area of ​​the present invention;

[0041] Fig.19 This is a similar schematic diagram of the lithology of the present invention. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] A method for classifying the genetic types of seepage barriers in deep-sea waterways of the present invention specifically defines and classifies the seepage barriers in different waterways based on the morphology, scale, lithology, distribution location and genesis of the seepage barriers in field outcrops. Specifically, as shown in Table 1, the sedimentation process, scale, lithology, distribution location and gravity flow genetic type of the deep-sea waterway are firstly obtained, and then the seepage barriers are divided into four categories based on the gravity flow genetic type, namely, landslide-induced seepage barriers, debris flow-induced seepage barriers, low-density turbidity current-induced seepage barriers and semi-pelagic deposition-induced seepage barriers. Then, the seepage barrier genetic type is further refinedly classified in combination with the lithology, scale, distribution location and sedimentation process of the seepage barrier.

[0044] Table 1

[0045]

[0046]

[0047] There are 4 major categories and 10 minor categories of seepage barriers in deep water channels. The specific classification results are as follows:

[0048] 1) Seepage barrier caused by landslide;

[0049] ① Seepage barrier caused by landslide and gravel-containing mudstone;

[0050] like Figure 1 , 2 As shown, they are mostly lens-shaped, and the rock types are mainly mudstone and gravel-bearing mudstone. They are 3-6m thick and 100-300m wide. They are often distributed on the edge of waterways and are mostly formed by the collapse of early overlying mudstone.

[0051] ② Seepage barrier caused by landslide siltstone;

[0052] like Figure 1 , 3 As shown, they are mostly lens-shaped, with the main rock type being siltstone, 0.5-3m thick and 10-20m wide. They are often distributed on the edge of waterways and are mostly the collapse of the inner natural levees formed in the early stage.

[0053] 2) debris flow-induced seepage barriers;

[0054] ① The seepage barrier originated from the mud-conglomerate retained at the bottom;

[0055] like Figure 4 , 5 As shown, they are mostly lens-shaped and layered, and the rock type is mainly mud conglomerate, 1-3m thick and 10-100m wide. They are often distributed at the bottom of the waterway, and a small part is sandwiched between secondary waterway units. Most of them are mud gravel formed by erosion at the bottom of the waterway.

[0056] ② Pebble mudstone-derived seepage barrier;

[0057] like Figure 4 , 6 As shown, they are mostly lens-shaped (flat top and convex bottom) and layered. The lithology is mainly pebble mudstone, 2-8m thick and 50-470m wide. They are often distributed at the bottom of waterways and are mostly event-induced terrigenous transport deposits. Pebbly mudstone is also bottom-retained deposit, but it is different from bottom-retained mud gravel in that the pebbles in the former are transported from the terrigenous source over a long distance and are distant source deposits, while the gravels in the latter are formed by original erosion and are near-source / original deposits.

[0058] ③ Seepage barrier caused by muddy debris flow;

[0059] like Figure 7 , 8 As shown, they are mostly lens-shaped, partially layered, and V-shaped. The rock types are mainly gravel mudstone and mudstone. They are 1-10m thick and 50-700m wide. They are often distributed throughout a single waterway and are mostly eroded and filled by mud-rich debris flows.

[0060] ④ Lateral mud-conglomerate-induced seepage barrier;

[0061] like Fig. 9 , 10 As shown, they are mostly wedge-shaped or S-shaped, and the rock type is mainly muddy clastic conglomerate, 0.1-2m thick and 5-60m wide. They are often distributed between lateral accumulation secondary waterways, and are mostly formed by mud and gravel eroded at the edge or bottom of the waterway, and then formed by lateral accumulation.

[0062] 3) Seepage barriers caused by low-density turbidites;

[0063] ① Seepage barrier of layered mudstone origin;

[0064] like Fig.11 , 12 As shown, they are mostly layered / banded, with the main rock types being mudstone, shale, and siltstone. They are 0.2-5m thick and 20-100m wide. They are often distributed between secondary waterways and are mostly formed in the late stage of gravity flow deposition.

[0065] ② Lateral mudstone-induced seepage barrier;

[0066] like Fig.13 , 14 As shown, they are mostly wedge-shaped, with the main rock type being mudstone, 0.01-0.1m thick and 0.2-1m wide. They are often distributed at the top of the waterway, gradually tapering from top to bottom, and are often formed by lateral accumulation of mudstone when the sand supply decreases.

[0067] ③ The seepage barrier caused by mudstone covering the road;

[0068] like Fig.15 , 16 As shown, they are mostly wedge-shaped and layered, with the main rock types being mudstone and shale. They are 0.1-1.5m thick and >20m wide. They are often distributed at the bottom and edge of waterways, and are deposited at the tail of turbidity currents.

[0069] 4) seepage barriers of hemipelagic sedimentary origin;

[0070] ① Seepage barrier of hemipelagic drapery mudstone origin;

[0071] like Fig.17 , 18 As shown, they are mostly layered, with the main rock types being mudstone and shale, 1-30m thick and >200m wide, mainly distributed at the top of a single waterway and formed by the sedimentation of semi-pelagic suspended matter during the period of high sea level.

[0072] The above description is not intended to limit the present invention in any form. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A method for classifying the causes of seepage barriers in deep-sea channels, characterized in that: The following steps are involved: Obtain the sedimentation process, scale, lithology, distribution location and gravity flow genesis type of deep-sea channels; Based on the gravity flow genesis of deep-sea channels, the genesis of seepage barriers in deep-sea channels can be divided into seepage barriers caused by landslide, seepage barriers caused by debris flow, seepage barriers caused by low-density turbidite, and seepage barriers caused by semi-pelagic deposition. Combined with the lithology, scale, distribution location and sedimentary process of the seepage barrier, the genetic types of the seepage barrier are further divided into fine categories; The landslide-induced seepage barrier is finely divided into landslide-induced gravel-containing mudstone-induced seepage barrier and landslide-induced siltstone-induced seepage barrier; The debris flow-induced seepage barrier is finely divided into bottom-retained mud conglomerate-induced seepage barrier, pebble mudstone-induced seepage barrier, mud debris flow-induced seepage barrier, and lateral accumulation mud conglomerate-induced seepage barrier. The low-density turbidite-induced seepage barrier is finely divided into: layered mudstone-induced seepage barrier, lateral mudstone-induced seepage barrier, and overlying mudstone-induced seepage barrier; The hemipelagic sedimentary origin seepage barrier is finely divided into hemipelagic drape mudstone origin seepage barrier.

2. A method for classifying the causes of seepage barriers in deep sea waterways according to claim 1, characterized in that: The seepage barrier caused by the landslide and gravel-containing mudstone is as follows: the lithology is mudstone and gravel-containing mudstone, with a thickness of 3-6m and a width of 100-300m. It is distributed at the edge of the waterway and is formed by the early overlying mudstone landslide.

3. A method for classifying the causes of seepage barriers in deep sea waterways according to claim 1, characterized in that: The siltstone-induced seepage barrier is: siltstone, 0.5-3m thick, 10-20m wide, distributed at the edge of the waterway, and was formed by the early inner natural levee collapse.

4. A method for classifying the causes of seepage barriers in deep sea waterways according to claim 1, characterized in that: The bottom retained mud-conglomerate-induced seepage barrier is: the lithology is mud-conglomerate, 1-3m thick, 10-100m wide, distributed at the bottom of the waterway or sandwiched between secondary waterway units, and is mud-conglomerate formed by erosion at the bottom of the waterway.

5. A method for classifying the causes of seepage barriers in deep sea waterways according to claim 1, characterized in that: The pebble mudstone-induced seepage barrier is: the lithology is pebble mudstone, 2-8m thick, 50-470m wide, distributed at the bottom of the waterway, and is an event-induced terrigenous transport deposit.

6. A method for classifying the causes of seepage barriers in deep sea waterways according to claim 1, characterized in that: The seepage barrier caused by muddy debris flow is: the rock type is gravel mudstone and mudstone, with a thickness of 1-10m and a width of 50-700m, distributed throughout the single waterway, and is eroded and filled by mud-rich debris flow.

7. A method for classifying the causes of seepage barriers in deep sea waterways according to claim 1, characterized in that: The lateral accumulation muddy conglomerate-induced seepage barrier is: the lithology is muddy clastic conglomerate, 0.1-2m thick, 5-60m wide, distributed between lateral accumulation secondary waterways, formed by muddy gravel eroded at the edge or bottom of the waterway, and then laterally accumulated.

8. A method for classifying the causes of seepage barriers in deep sea waterways according to claim 1, characterized in that: The layered mudstone-induced seepage barrier is composed of mudstone, shale and siltstone, with a thickness of 0.2-5 m and a width of 20-100 m, distributed between secondary waterways and formed in the late stage of gravity flow deposition.

9. A method for classifying the causes of seepage barriers in deep sea waterways according to claim 1, characterized in that: The seepage barrier of lateral accumulation mudstone is as follows: the lithology is mudstone, with a thickness of 0.01-0.1m and a width of 0.2-1m, distributed on the top of the waterway and formed by lateral accumulation of mudstone.

10. A method for classifying the causes of seepage barriers in deep sea waterways according to claim 1, characterized in that: The mudstone-derived seepage barrier is composed of mudstone and shale, with a thickness of 0.1-1.5m and a width of >20m, distributed at the bottom and edge of the waterway; The semi-pelagic mudstone-derived seepage barrier is composed of mudstone and shale, with a thickness of 1-30 m and a width of >200 m, distributed on the top of a single waterway.

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