Device and method for simulating stratum settlement after offshore shallow gas blowout

Abstract

The invention relates to a device and method for simulating stratum settlement after blowout of an offshore shallow gas well, and the device comprises a settlement simulator which is used for simulating a shaft and an external environment; the gas injection system is connected with the settlement simulator and used for injecting gas into the settlement simulator and simulating the gas blowout condition; and the load pressure system is connected with the settlement simulator and used for adding oil pressure to the settlement simulator and simulating the pressurization condition. According to the method, the settlement characteristics of the shallow gas blowout stratum are visually evaluated, and technical support is provided for researching and preventing safety accidents caused by shallow gas blowout.

Description

Technical Field

[0001] The present invention relates to the technical field of oil drilling safety, and particularly to a device and method for simulating formation settlement after a shallow gas blowout in the sea. Background Art

[0002] Currently, the global energy supply and demand situation is tightening, and marine oil and gas resources are of great significance for ensuring the security and stability of the global energy supply. However, there are many challenges and problems in the drilling and production process of marine oil and gas. For example, in the formations of offshore oilfields such as the Bohai Sea and the South China Sea in China, high-pressure shallow gas pockets of different scales are developed. If the prediction is inaccurate or the construction is improper during the drilling process, it is extremely easy to induce a shallow gas blowout, causing huge economic losses.

[0003] Submarine shallow gas generally refers to organic gas accumulated in the formation within 1000 m below the seabed. The formation pressure is relatively high, the distribution range is limited, and it has no mining value. The shallow gas layer generally has loose formation cementation. Therefore, a shallow gas blowout caused by improper handling often carries out a large amount of mud and sand, resulting in formation voids, and causing overall deformation of the formation under the influence of the rock self-weight. In severe cases, it can lead to platform instability. During the drilling process of offshore infill wells, due to the normal production of other wells on the platform, after a blowout, not only accidents such as fires on the offshore platform and wellhead devices of production wells will occur, but also the formation settlement problem caused by the blowout seriously threatens the wellbore safety of adjacent production wells. It is necessary to clarify the formation settlement characteristics after a blowout in order to provide technical support for the safety evaluation of the resumption of production of adjacent production wells after a blowout.

[0004] The existing research on the law of formation settlement mainly focuses on formation settlement caused by tunnel excavation, coal seam mining, shallow hydrate mining, frozen soil melting, and surface engineering. The research methods mainly include experiments, theoretical analysis, numerical simulation, etc. However, there is less research on the formation settlement problem after a blowout in a well encountering a high-pressure shallow gas layer during oil exploitation, and it is only limited to numerical simulation research, lacking experimental verification. In addition, in recent years, experts have gradually paid attention to the problem of shallow gas blowout during the oil drilling process, but most of them can only quantitatively evaluate the relationship between formation pressure and gas injection and sandblasting volume during a shallow gas blowout, and cannot simulate the law of formation settlement during a blowout and the formation deformation characteristics around the wellbore of adjacent production wells.

[0005] Therefore, it is urgent to develop a device and method for simulating formation settlement after a shallow gas blowout in the sea to provide technical support for the research on the formation settlement problem after a blowout. Summary of the Invention

[0006] Aiming at the above problems, the purpose of the present invention is to provide a device and method for simulating formation settlement after a shallow gas blowout in the sea, visually evaluate the formation settlement characteristics of a shallow gas blowout, and provide technical support for researching and preventing safety accidents caused by a shallow gas blowout.

[0007] To achieve the above object, the present invention adopts the following technical solutions: The formation settlement device for simulating the formation settlement after the blowout of a shallow offshore gas well according to the present invention includes: a settlement simulator for simulating the wellbore and the external environment; an air injection system connected to the settlement simulator for injecting air into the settlement simulator to simulate the gas blowout situation; and a load pressure system connected to the settlement simulator for applying oil pressure to the settlement simulator to simulate the pressurized condition.

[0008] For the formation settlement device, preferably, the settlement simulator includes: a left wellbore, a right wellbore, a sealing housing, a square ring outer shell, a left pressing plate, an intermediate pressing plate, a right pressing plate, and a square barrel; The square ring outer shell is fixedly arranged on the top of the square barrel, and the two form an accommodation space with an upper opening and a lower closure; the accommodation space is filled with a first dense sand layer, a loose sand layer, and a second dense sand layer in sequence from bottom to top, 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 outer shell and extends into the loose sand layer; The right wellbore passes through the second dense sand layer and the loose sand layer in sequence from above the square ring outer shell and extends into the first dense sand layer; The left pressing plate is arranged at the opening of the square ring outer shell between the side wall of the square ring outer shell and the left wellbore; the intermediate pressing plate is arranged at the opening of the square ring outer shell between the left wellbore and the right wellbore; the right pressing plate is arranged at the opening of the square ring outer shell between the right wellbore and the side wall of the square ring outer shell; The sealing housing is arranged outside the whole 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.

[0009] For the formation settlement device, preferably, the sealing housing is made of acrylic transparent material.

[0010] For the formation settlement device, preferably, the air injection system includes: a safety valve, an air tank, a pressure gauge, a gas boosting system, and a pressure regulating valve; The air tank, the gas boosting system, and the pressure regulating valve are connected in series through pipelines and then connected to the air injection hole; The air tank is connected with a safety valve through a pipeline; Pressure gauges are respectively arranged on the pipeline between the air tank and the gas boosting system and on the pipeline between the pressure regulating valve and the air injection hole; A safety valve is connected to the pipeline between the pressure regulating valve and the air injection hole.

[0011] The described formation settlement device, preferably, the load pressure system includes an oil source, a hydraulic servo system, a hydraulic pump, and a hydraulic support; The hydraulic supports are respectively arranged on the left pressing plate, the middle pressing plate, and the right pressing plate; The oil source, the hydraulic servo system, and the hydraulic pump are connected in series through pipelines to form a load pressure assembly; One load pressure assembly is connected to each hydraulic support.

[0012] The described formation settlement device, preferably, the joint parts between the left wellbore and the sealing housing and between the right wellbore and the sealing housing are respectively filled with sealing colloid.

[0013] The present invention also provides a settlement method for a formation settlement device simulating the formation settlement after a shallow gas blowout in the sea, including the following steps: (1) Configure the sand body; (2) Connect the formation settlement device and fill the configured sand body into the formation settlement device as required; (3) Conduct a formation settlement simulation experiment after the blowout, specifically: through the load pressure system, make the hydraulic support apply a certain initial force to the left pressing plate, the middle pressing plate, and the right pressing plate, and record the decay curve of the initial force over time; inject gas into the settlement simulator through the gas injection system to simulate the gas blowout, and record the decay curve of the initial force over time; after the blowout simulation for a set time, observe the sand body settlement situation and obtain the decay curve of the initial force over time during the whole process; (4) Repeat the simulation experiment in step (3) several times; (5) Shut down the experimental device and conduct data processing, and study the formation settlement problem after the blowout based on the data.

[0014] Due to the adoption of the above technical solutions, the present invention has the following advantages: The present invention aims at the problem of the formation deformation characteristics after a blowout occurs when drilling through a shallow high-pressure gas layer during offshore oil drilling, visually simulates the formation settlement characteristics during a shallow gas blowout, obtains the formation settlement law after the blowout under different shallow gas layer pressures, and visually monitors the formation deformation characteristics around the production well adjacent to the blowout well.

[0015] Since the formation settlement problem caused by the blowout threatens the wellbore safety of adjacent production wells, therefore, the present invention can provide technical support for the safety assessment of the resumption of production of adjacent production wells after the blowout. Description of the Drawings

[0016] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Throughout the accompanying drawings, the same reference numerals are used to represent the same components. In the accompanying drawings: Figure 1 It is a schematic diagram of the structure of the formation settlement device after the shallow gas blowout in the present invention; Figure 2 yes Figure 1 Top view of the .

[0017] The reference numerals in the figures are as follows: 1-safety valve; 2-gas tank; 3-pressure gauge; 4-gas boosting 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-middle 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 hole; 18-oil source; 19-hydraulic servo system; 20-hydraulic pump. DETAILED DESCRIPTION

[0018] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0019] The present invention provides a device for simulating formation settlement after offshore shallow gas blowout. By targeting the formation deformation characteristics after a blowout occurs when drilling into a shallow high-pressure gas layer during offshore oil drilling, the device visualizes the formation settlement characteristics during a shallow gas blowout, obtains the formation settlement law after a blowout under different shallow gas layer pressures, and visualizes the formation deformation characteristics around the production wells adjacent to the blowout well. Thus, technical support is provided for studying and preventing safety accidents caused by shallow gas blowouts.

[0020] like Figure 1 As shown, the device for simulating formation settlement after offshore shallow gas blowout provided by the present invention includes: a settlement simulator, used to simulate the wellbore and external environment; a gas injection system, connected to the settlement simulator, used to inject gas into the settlement simulator to simulate the gas blowout situation; a load pressure system, connected to the settlement simulator, used to pressurize the settlement simulator to simulate the pressurized condition.

[0021] In the above embodiments, preferably, the settlement simulator includes: a left wellbore 6, a right wellbore 7, a sealing housing 9, a square ring outer shell 10, a left pressing plate 13, an intermediate pressing plate 12, a right pressing plate 11, and a square barrel 16; The square ring outer shell 10 is fixedly arranged at the top of the square barrel 16, and the two form a receiving space with an upper opening and a lower closure; the receiving space is filled with a first dense sand layer 14-1, a loose sand layer 15, and a second dense sand layer 14-2 in sequence from bottom to top, and the upper surface of the loose sand layer 15 is flush with the top opening of the square barrel 16; The left wellbore 6 passes through the second dense sand layer 14-2 above the square ring outer shell 10 and extends into the loose sand layer 15; the right wellbore 7 passes through the second dense sand layer 14-2 and the loose sand layer 15 in sequence above the square ring outer shell 10 and then extends into the first dense sand layer 14-1; The left pressing plate 13 is arranged at the opening of the square ring outer shell 10 between the side wall of the square ring outer shell 10 and the left wellbore 6; the intermediate pressing plate 12 is arranged at the opening of the square ring outer shell 10 between the left wellbore 6 and the right wellbore 7; the right pressing plate 11 is arranged at the opening of the square ring outer shell 10 between the right wellbore 7 and the side wall of the square ring outer shell 10; The sealing housing 9 is arranged outside the whole formed by the square ring outer shell 10 and the square barrel 16; An air injection hole 17 is arranged on the side wall of the square barrel 16.

[0022] In the above embodiments, preferably, the sealing housing 9 is made of acrylic transparent material.

[0023] In the above embodiments, preferably, the gas injection system includes: a safety valve 1, a gas tank 2, a pressure gauge 3, a gas boosting system 4, and a pressure regulating valve 5; the gas tank 2, the gas boosting system 4, and the pressure regulating valve 5 are connected in series through pipelines and then connected to the air injection hole 17; the gas tank 2 is connected with a safety valve 1 through a pipeline; pressure gauges 3 are respectively arranged on the pipeline between the gas tank 2 and the gas boosting system 4 and on the pipeline between the pressure regulating valve 5 and the air injection hole 17; a safety valve 1 is connected to the pipeline between the pressure regulating valve 5 and the air injection hole 17. Thus, by injecting gas through the gas injection system, the blowout phenomenon can be simulated.

[0024] In the above embodiments, 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 arranged on the left pressing plate 13, the intermediate pressing plate 12, and the right pressing 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; each hydraulic support 8 is connected to one of the load pressure assemblies. Thus, the formation pressurization environment around the wellbore can be simulated.

[0025] In the above embodiments, preferably, the joint portions between the left wellbore 6 and the sealing housing 9 and between the right wellbore 7 and the sealing housing 9 are respectively filled with sealing colloid. Thus, a sealed environment can be simulated.

[0026] The present invention also provides a settlement method for a formation settlement device simulating a formation settlement after a blowout of an offshore shallow gas well, comprising the following steps: (1) Configure sand bodies: Configure sand bodies with different degrees of looseness according to needs, including dense sand bodies and loose sand bodies; (2) Connect the formation settlement device and fill the configured sand bodies into the formation settlement device as required; specifically, connect in the following manner: Fill the lower part of the square barrel with dense sand bodies, and leave a gap for the right wellbore. Fill the upper part of the dense sand bodies with loose sand bodies, and fill the loose sand bodies flush with the upper part of the square barrel, and leave gaps for the left wellbore and the right wellbore; Install the left pressing plate, the middle pressing plate, and the right pressing plate on the square ring housing in sequence. Fill the square ring housing with dense sand bodies, and leave gaps for the left wellbore and the right wellbore; Install the square ring housing component with the left pressing plate, the middle pressing plate, and the right pressing plate and filled with dense sand bodies on the upper part of the square barrel component; Place components such as the square ring housing and the square barrel in the sealing housing, and install hydraulic supports on the upper parts of the left pressing plate, the middle pressing plate, and the right pressing plate respectively. The upper parts of the hydraulic supports are in contact with the upper part inside the sealing housing; Each hydraulic support is connected to a load pressure system containing a hydraulic pump; The air injection hole is connected to an air injection system containing a pressure regulating valve; The left wellbore passes through the sealing housing, through the pores of the left pressing plate and the middle pressing plate, through the pores of the upper dense sand bodies, and is placed inside the loose sand bodies; The right wellbore passes through the sealing housing, through the pores of the middle pressing plate and the right pressing plate, through the pores of the upper dense sand bodies, through the loose sand bodies, and is placed inside the lower dense sand bodies; Fill the joint portions between the left wellbore and the sealing housing and between the right wellbore and the sealing housing with sealing colloid for sealing; Connect the oil source to the hydraulic servo system; Connect the hydraulic servo system to the hydraulic pump; After connecting the oil source, the hydraulic servo system, and the hydraulic pump, connect them to each hydraulic support; Connect the gas tank to the gas boosting system; Connect the gas boosting system to the pressure regulating valve; Connect the pressure regulating valve to the air inlet hole; Install safety valves between the gas tank, between the pressure regulating valve and the air inlet hole; Install pressure gauges between the gas tank and the gas boosting system, and between the pressure regulating valve and the air injection hole.

[0027] (3) Conduct a formation settlement simulation experiment after a blowout, specifically: Through the load pressure system, make the hydraulic supports apply a certain initial force to the left pressing plate, the middle pressing plate, and the right pressing plate, and record the decay curve of the initial force over time; Inject gas into the settlement simulator through the air injection system to simulate a gas blowout, and record the decay curve of the initial force over time; After the blowout simulation for a set time, observe the settlement situation of the sand bodies and obtain the decay curve of the initial force over time during the whole process; (4) Repeat the simulation experiment in step (3) several times; (5) Close the experimental device and process the data, and study the formation settlement problem after the blowout according to the data.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for simulating stratum subsidence after offshore shallow gas blowout, characterized in that: include: Subsidence simulator, used to simulate the wellbore and external environment; A gas injection system, connected to the settlement simulator, is used to inject gas into the settlement simulator to simulate a gas blowout situation; The load pressure system is connected to the settlement simulator and is used to pressurize the settlement simulator to simulate the pressurized condition.

2. The stratum subsidence device according to claim 1, characterized in that: The settlement simulator comprises: a left wellbore, a right wellbore, a sealing shell, a square ring shell, a left pressure plate, a middle pressure plate, a right pressure plate and a square barrel; The square ring shell is fixedly arranged on the top of the square barrel, and the two form a receiving space with an upper opening and a lower closed portion; the receiving space is filled with a first dense sand body layer, a loose sand body layer and a second dense sand body layer in sequence from bottom to top, and the upper surface of the loose sand body 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 through the second dense sand layer and the loose sand layer in sequence from above the square ring shell and then extends into the first dense sand layer; The left pressure plate is arranged at the opening of the square ring shell between the side wall of the square ring shell and the left shaft; the middle pressure plate is arranged at the opening of the square ring shell between the left shaft and the right shaft; the right pressure plate is arranged at the opening of the square ring shell between the right shaft and the side wall of the square ring shell; The sealing shell is arranged outside the integral body formed by the square ring shell and the square barrel; The side wall of the square barrel is provided with air injection holes.

3. The stratum subsidence device according to claim 2, characterized in that: The sealed shell is made of transparent acrylic material.

4. The stratum subsidence device according to claim 2, 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 boosting system and pressure regulating valve are connected in series through pipelines in sequence and then connected to the gas injection hole; The gas tank is connected to a safety valve via a pipeline; Pressure gauges are respectively provided 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 hole; A safety valve is connected to the pipeline between the pressure regulating valve and the gas injection hole.

5. The stratum subsidence device according to claim 2, characterized in that: The load pressure system includes an oil source, a hydraulic servo system, a hydraulic pump and a hydraulic support; The left pressure plate, the middle pressure plate and the right pressure plate are respectively provided with the hydraulic support; The oil source, the hydraulic servo system and the hydraulic pump are connected in series through pipelines to form a load pressure assembly; Each of the hydraulic supports is connected to a load pressure assembly.

6. The stratum subsidence device according to claim 2, characterized in that: The joint portion between the left shaft and the sealing shell and the joint portion between the right shaft and the sealing shell are filled with sealing colloid respectively.

7. A method for simulating the formation settlement after offshore shallow gas blowout according to any one of claims 2 to 6, characterized in that: The steps include: (1) Sand body configuration; (2) Connect the formation settlement device and fill the configured sand body into the formation settlement device as required; (3) Conduct a simulation experiment of formation settlement 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; inject gas into the settlement simulator through the gas injection system to simulate gas blowout, and record the decay curve of the initial force over time; after the blowout simulation for a set time, observe the settlement of the sand body and obtain the decay curve of the initial force over time in the whole process; (4) Repeat the simulation experiment in step (3) several times; (5) Close the experimental device and process the data, and study the formation subsidence problem after the blowout based on the data.

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