A device and method for simulating formation subsidence after a shallow marine gas well blowout

Abstract

The present application relates to a kind of device and method for simulating formation subsidence after offshore shallow gas well blowout, wherein the device comprises: a subsidence simulator for simulating wellbore and external environment; a gas injection system connected to the subsidence simulator for injecting gas into the subsidence simulator to simulate gas blowout conditions; and a load pressure system connected to the subsidence simulator for applying oil pressure to the subsidence simulator to simulate pressurized conditions. The present application can visually evaluate the formation subsidence characteristics after shallow gas well blowout, providing technical support for studying and preventing safety accidents caused by shallow gas well blowout.

Description

Technical Field

[0001] This invention relates to the field of oil drilling safety technology, specifically to a device and method for simulating formation subsidence after a blowout of a shallow offshore gas well. Background Technology

[0002] Currently, the global energy supply and demand situation is tightening, and offshore oil and gas resources are of great significance to ensuring the security and stability of global energy supply. However, the drilling and extraction of offshore oil and gas faces many challenges and difficulties. For example, in the formations of offshore oil fields in the Bohai Sea and South China Sea, there are high-pressure shallow gas pockets of varying sizes. If the prediction is inaccurate or the construction is improper, shallow gas well blowouts can easily be induced, causing huge economic losses.

[0003] Shallow gas formations generally refer to organic gases accumulated in strata shallower than 1000 meters below the seabed. These formations have high pressure, limited distribution, and are not exploitable. Shallow gas formations are typically loosely cemented, so blowouts caused by improper handling often carry large amounts of mud and sand, leading to formation depletion. Under the weight of the rocks, this causes overall formation deformation, which can severely destabilize the platform. During offshore infill drilling, since other wells on the platform are producing normally, a blowout can lead not only to accidents such as fires on the offshore platform and wellhead equipment, but also serious formation subsidence that threatens the safety of adjacent production wells. Therefore, understanding the characteristics of formation subsidence after a blowout is crucial for providing technical support for safety assessments of resuming production in nearby wells.

[0004] Existing research on formation subsidence mainly focuses on subsidence caused by tunnel excavation, coal seam mining, shallow hydrate extraction, permafrost thawing, and surface engineering. Research methods primarily include experiments, theoretical analysis, and numerical simulations. However, research on formation subsidence following blowouts from high-pressure shallow gas reservoirs encountered during oil drilling is limited and largely confined to numerical simulations, lacking experimental verification. Furthermore, while experts have increasingly focused on shallow gas well blowouts in oil drilling in recent years, most studies only quantitatively evaluate the relationship between formation pressure and the amount of gas and sand injected during a blowout, failing to simulate the formation subsidence patterns and deformation characteristics of the formation around the production well.

[0005] Therefore, it is urgent to develop a device and method to simulate formation subsidence after a blowout of shallow offshore gas wells, so as to provide technical support for the study of formation subsidence problems after a blowout. Summary of the Invention

[0006] To address the aforementioned problems, the purpose of this invention is to provide a device and method for simulating formation subsidence after a shallow gas well blowout at sea, to visually evaluate the formation subsidence characteristics of a shallow gas well blowout, and to provide technical support for the study and prevention of safety accidents caused by shallow gas well blowouts.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The formation settlement device for simulating shallow offshore gas well blowout according to the present invention includes: a settlement simulator for simulating the wellbore and external environment; a gas injection system connected to the settlement simulator for injecting gas into the settlement simulator to simulate a gas blowout; and a load pressure system connected to the settlement simulator for pressurizing the settlement simulator to simulate a pressurized state.

[0009] Preferably, the settlement simulator of the aforementioned stratum settlement device includes: a left shaft, a right shaft, a sealed shell, a square ring shell, a left pressure plate, a middle pressure plate, a right pressure plate, and a square barrel;

[0010] The outer shell of the square ring is fixedly installed on the top of the square barrel, and the two form an accommodating space with an open top and a closed bottom; the accommodating space is filled from bottom to top with a first dense sand layer, a loose sand layer and a second dense sand layer, and the upper surface of the loose sand layer is flush with the top opening of the square barrel.

[0011] The left wellbore passes through the second dense sand layer from above the square ring shell and extends into the loose sand layer;

[0012] The right wellbore passes sequentially through the second dense sand layer and the loose sand layer from above the square ring shell and then extends into the first dense sand layer;

[0013] The left pressure plate is disposed at the opening of the square ring shell between the side wall of the square ring shell and the left well shaft; the middle pressure plate is disposed at the opening of the square ring shell between the left well shaft and the right well shaft; the right pressure plate is disposed at the opening of the square ring shell between the right well shaft and the side wall of the square ring shell.

[0014] The sealing housing is disposed outside the integral formed by the square ring outer shell and the square barrel;

[0015] The side wall of the square barrel is provided with an air injection hole.

[0016] Preferably, in the aforementioned ground subsidence device, the sealed housing is made of transparent acrylic material.

[0017] Preferably, the gas injection system of the aforementioned formation settlement device includes: a safety valve, a gas tank, a pressure gauge, a gas pressurization system, and a pressure regulating valve;

[0018] The gas tank, gas pressurization system and pressure regulating valve are connected in series via pipelines to the gas injection port.

[0019] The gas tank is connected to a safety valve via a pipeline;

[0020] Pressure gauges are installed on the pipeline between the gas tank and the gas pressurization system, and on the pipeline between the pressure regulating valve and the gas injection port.

[0021] A safety valve is connected to the pipeline between the pressure regulating valve and the air injection port.

[0022] Preferably, the load pressure system of the aforementioned formation settlement device includes an oil source, a hydraulic servo system, a hydraulic pump, and a hydraulic support.

[0023] The hydraulic support is respectively provided on the left pressure plate, the middle pressure plate and the right pressure plate;

[0024] The oil source, the hydraulic servo system, and the hydraulic pump are connected in series via pipelines to form a load pressure assembly.

[0025] Each of the hydraulic supports is connected to a load pressure assembly.

[0026] Preferably, in the formation settlement device, the joint between the left wellbore and the sealing shell, and the joint between the right wellbore and the sealing shell, are respectively filled with sealing colloid.

[0027] The present invention also provides a settling method for a formation settling device simulating a blowout of a shallow offshore gas well, comprising the following steps:

[0028] (1) Configure sand bodies;

[0029] (2) Connect the ground settlement device and fill the prepared sand body into the ground settlement device as required;

[0030] (3) Conduct a formation settlement simulation experiment after blowout, specifically: through the load pressure system, the hydraulic support applies a certain initial force to the left pressure plate, the middle pressure plate and the right pressure plate, and records the decay curve of the initial force over time; through the gas injection system, gas is injected into the settlement simulator to simulate a gas blowout, and the decay curve of the initial force over time is recorded; after a blowout simulation of a set time, the sand body settlement is observed, and the decay curve of the initial force over time is obtained throughout the process;

[0031] (4) Repeat the simulation experiment in step (3) several times;

[0032] (5) Shut down the experimental device and process the data, and study the formation subsidence problem after the blowout based on the data.

[0033] The present invention has the following advantages due to the adoption of the above technical solutions:

[0034] This invention addresses the issue of formation deformation characteristics after a blowout occurs when drilling into a shallow high-pressure gas layer during offshore oil drilling. It visualizes and simulates the formation subsidence characteristics during a shallow gas blowout, obtains the formation subsidence patterns after a blowout under different shallow gas layer pressures, and visualizes and monitors the formation deformation characteristics around production wells adjacent to the blowout well.

[0035] Since the formation subsidence caused by a blowout can threaten the wellbore safety of adjacent production wells, this invention can provide technical support for the safety assessment of the resumption of production by adjacent production wells after a blowout. Attached Figure Description

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0037] Figure 1 This is a schematic diagram of the formation settlement device after shallow gas well blowout in this invention;

[0038] Figure 2 yes Figure 1 Top view.

[0039] The labels for the attached figures are as follows:

[0040] 1-Safety valve; 2-Gas tank; 3-Pressure gauge; 4-Gas pressurization system; 5-Pressure regulating valve; 6-Left wellbore; 7-Right wellbore; 8-Hydraulic support; 9-Sealing shell; 10-Square ring shell; 11-Right pressure plate; 12-Intermediate pressure plate; 13-Left pressure plate; 14-1 First dense sand layer; 14-2 Second dense sand layer; 15-Loose sand layer; 16-Square barrel; 17-Gas injection port; 18-Oil source; 19-Hydraulic servo system; 20-Hydraulic pump. Detailed Implementation

[0041] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0042] This invention provides a device for simulating formation subsidence after a blowout from a shallow offshore gas well. Addressing the issue of formation deformation characteristics following a blowout from a shallow, high-pressure gas layer encountered during offshore oil drilling, it visualizes and simulates formation subsidence characteristics during a shallow gas well blowout, obtaining the formation subsidence patterns under different shallow gas layer pressures. It also visualizes and monitors the formation deformation characteristics around production wells adjacent to the blowout well. Therefore, it provides technical support for researching and preventing safety accidents caused by shallow gas well blowouts.

[0043] like Figure 1 As shown, the formation settlement device for simulating shallow offshore gas well blowout provided by the present invention includes: a settlement simulator for simulating the wellbore and external environment; a gas injection system connected to the settlement simulator for injecting gas into the settlement simulator to simulate a gas blowout; and a load pressure system connected to the settlement simulator for pressurizing the settlement simulator to simulate a pressurized state.

[0044] In the above embodiments, preferably, the settlement simulator includes: a left shaft 6, a right shaft 7, a sealed shell 9, a square ring shell 10, a left pressure plate 13, a middle pressure plate 12, a right pressure plate 11, and a square barrel 16.

[0045] The outer shell 10 of the square ring is fixedly set on the top of the square barrel 16, and the two form an accommodating space with an open top and a closed bottom. The accommodating space is filled from bottom to top with a first dense sand layer 14-1, a loose sand layer 15 and a second dense sand layer 14-2, and the upper surface of the loose sand layer 15 is flush with the top opening of the square barrel 16.

[0046] The left shaft 6 passes through the second dense sand layer 14-2 from above the square ring shell 10 and extends into the loose sand layer 15; the right shaft 7 passes through the second dense sand layer 14-2 and the loose sand layer 15 from above the square ring shell 10 and then extends into the first dense sand layer 14-1.

[0047] The left pressure plate 13 is disposed at the opening of the square ring shell 10 between the side wall of the square ring shell 10 and the left shaft 6; the middle pressure plate 12 is disposed at the opening of the square ring shell 10 between the left shaft 6 and the right shaft 7; the right pressure plate 11 is disposed at the opening of the square ring shell 10 between the right shaft 7 and the side wall of the square ring shell 10.

[0048] The sealing housing 9 is disposed outside the integral formed by the square ring housing 10 and the square barrel 16;

[0049] The side wall of the square bucket 16 is provided with an air injection hole 17.

[0050] In the above embodiments, preferably, the sealing housing 9 is made of transparent acrylic material.

[0051] In the above embodiment, preferably, the gas injection system includes: a safety valve 1, a gas tank 2, a pressure gauge 3, a gas pressurization system 4, and a pressure regulating valve 5; the gas tank 2, the gas pressurization system 4, and the pressure regulating valve 5 are connected in series via pipelines to the gas injection port 17; the gas tank 2 is connected to the safety valve 1 via a pipeline; pressure gauges 3 are respectively installed on the pipeline between the gas tank 2 and the gas pressurization system 4, and on the pipeline between the pressure regulating valve 5 and the gas injection port 17; the safety valve 1 is connected to the pipeline between the pressure regulating valve 5 and the gas injection port 17. Thus, by injecting gas through the gas injection system, a blowout phenomenon is simulated.

[0052] In the above embodiment, preferably, the load pressure system includes an oil source 18, a hydraulic servo system 19, a hydraulic pump 20, and a hydraulic support 8; hydraulic supports 8 are respectively installed on the left pressure plate 13, the middle pressure plate 12, and the right pressure plate 11; the oil source 18, the hydraulic servo system 19, and the hydraulic pump 20 are connected in series through pipelines to form a load pressure assembly; one load pressure assembly is connected to each hydraulic support 8. Thus, the pressurization environment of the formation surrounding the wellbore can be simulated.

[0053] In the above embodiments, preferably, the joint between the left wellbore 6 and the sealing shell 9, and the joint between the right wellbore 7 and the sealing shell 9, are respectively filled with sealing adhesive. This simulates a sealed environment.

[0054] The present invention also provides a settling method for a formation settling device simulating a blowout of a shallow offshore gas well, comprising the following steps:

[0055] (1) Sand body configuration: Sand bodies with different degrees of looseness are configured as needed, including dense sand bodies and loose sand bodies;

[0056] (2) Connect the ground settlement device and fill the prepared sand body into the ground settlement device as required; specifically, connect it in the following way:

[0057] The lower part of the square barrel is filled with dense sand, leaving a gap for the right shaft. The upper part of the dense sand is filled with loose sand, which is filled to be flush with the top of the square barrel, leaving gaps for the left and right shafts. The square ring outer shell is sequentially fitted with a left pressure plate, a middle pressure plate, and a right pressure plate. The inside of the square ring outer shell is filled with dense sand, leaving gaps for the left and right shafts. The square ring outer shell component, equipped with the left, middle, and right pressure plates and filled with dense sand, is installed on top of the square barrel component. The square ring outer shell, square barrel, and other components are placed inside a sealed housing, and hydraulic supports are installed on the upper part of the left, middle, and right pressure plates, respectively. The upper part of the hydraulic supports contacts the upper part inside the sealed housing. Each hydraulic support is connected to a load pressure system containing a hydraulic pump. The air injection port is connected to an air injection system containing a pressure regulating valve. The left shaft passes through the sealed housing. The shaft passes through the gaps in the left and middle pressure plates, through the pores of the upper dense sand body, and is placed inside the loose sand body; the right shaft passes through the sealing shell, through the gaps in the middle and right pressure plates, through the pores of the upper dense sand body, through the loose sand body, and is placed inside the lower dense sand body; the joint between the left shaft and the sealing shell, and the joint between the right shaft and the sealing shell, are sealed with sealing colloid; the oil source is connected to the hydraulic servo system; the hydraulic servo system is connected to the hydraulic pump; after the oil source, hydraulic servo system, and hydraulic pump are connected, they are connected to each hydraulic support; the gas tank is connected to the gas booster system; the gas booster system is connected to the pressure regulating valve; the pressure regulating valve is connected to the air inlet; safety valves are installed on the gas tank, between the pressure regulating valve and the air inlet; pressure gauges are installed between the gas tank and the gas booster system, and between the pressure regulating valve and the air injection port.

[0058] (3) Conduct a formation settlement simulation experiment after blowout, specifically: through the load pressure system, the hydraulic support applies a certain initial force to the left pressure plate, the middle pressure plate and the right pressure plate, and records the decay curve of the initial force over time; through the gas injection system, gas is injected into the settlement simulator to simulate a gas blowout, and the decay curve of the initial force over time is recorded; after a blowout simulation of a set time, the sand body settlement is observed, and the decay curve of the initial force over time is obtained throughout the process;

[0059] (4) Repeat the simulation experiment in step (3) several times;

[0060] (5) Shut down the experimental device and process the data, and study the formation subsidence problem after the blowout based on the data.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for simulating formation subsidence after a blowout from a shallow offshore gas well, characterized in that, include: Settlement simulator, used to simulate well shaft and external environment; The gas injection system, connected to the settling simulator, is used to inject gas into the settling simulator to simulate a gas blowout. The load pressure system, connected to the settlement simulator, is used to pressurize the settlement simulator and simulate pressurized conditions. The settlement simulator includes: a left shaft, a right shaft, a sealed shell, a square ring shell, a left pressure plate, a middle pressure plate, a right pressure plate, and a square barrel; The outer shell of the square ring is fixedly installed on the top of the square barrel, and the two form an accommodating space with an open top and a closed bottom; the accommodating space is filled from bottom to top with a first dense sand layer, a loose sand layer and a second dense sand layer, and the upper surface of the loose sand layer is flush with the top opening of the square barrel. The left wellbore passes through the second dense sand layer from above the square ring shell and extends into the loose sand layer; The right wellbore passes sequentially through the second dense sand layer and the loose sand layer from above the square ring shell and then extends into the first dense sand layer; The left pressure plate is disposed at the opening of the square ring shell between the side wall of the square ring shell and the left well shaft; the middle pressure plate is disposed at the opening of the square ring shell between the left well shaft and the right well shaft; the right pressure plate is disposed at the opening of the square ring shell between the right well shaft and the side wall of the square ring shell. The sealing housing is disposed outside the integral formed by the square ring outer shell and the square barrel; The side wall of the square barrel is provided with an air injection hole.

2. The ground subsidence device according to claim 1, characterized in that, The sealed housing is made of transparent acrylic material.

3. The ground subsidence device according to claim 1, characterized in that, The gas injection system includes: a safety valve, a gas tank, a pressure gauge, a gas pressurization system, and a pressure regulating valve; The gas tank, gas pressurization system and pressure regulating valve are connected in series via pipelines to the gas injection port. The gas tank is connected to a safety valve via a pipeline; Pressure gauges are installed on the pipeline between the gas tank and the gas pressurization system, and on the pipeline between the pressure regulating valve and the gas injection port. A safety valve is connected to the pipeline between the pressure regulating valve and the air injection port.

4. The ground subsidence device according to claim 1, characterized in that, The load pressure system includes an oil source, a hydraulic servo system, a hydraulic pump, and a hydraulic support. The hydraulic support is respectively provided on the left pressure plate, the middle pressure plate and the right pressure plate; The oil source, the hydraulic servo system, and the hydraulic pump are connected in series via pipelines to form a load pressure assembly. Each of the hydraulic supports is connected to a load pressure assembly.

5. The ground subsidence device according to claim 1, characterized in that, The joint between the left wellbore and the sealing shell, and the joint between the right wellbore and the sealing shell, are respectively filled with sealing colloid.

6. A settling method based on the formation subsidence device simulating a shallow offshore gas well blowout as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Configure sand bodies; (2) Connect the ground settlement device and fill the prepared sand body into the ground settlement device as required; (3) Conduct a formation settlement simulation experiment after blowout, specifically: through the load pressure system, the hydraulic support applies a certain initial force to the left pressure plate, the middle pressure plate and the right pressure plate, and records the decay curve of the initial force over time; through the gas injection system, gas is injected into the settlement simulator to simulate a gas blowout, and the decay curve of the initial force over time is recorded; after a blowout simulation of a set time, the sand body settlement is observed, and the decay curve of the initial force over time is obtained throughout the process; (4) Repeat the simulation experiment in step (3) several times; (5) Shut down the experimental device and process the data, and study the formation subsidence problem after the blowout based on the data.

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