A hydraulic testing device and method for the bearing capacity of the bottom of a self-elevating drilling platform pile shoe

Abstract

This invention relates to a hydraulic testing device for the bottom bearing capacity of a self-elevating drilling platform pile shoe. Several hydraulic jacking mechanisms are spaced apart along the circumference of the pile shoe, each equipped with a pressure detection mechanism. These pressure detection mechanisms detect the depth of the pile shoe's penetration and the stress it experiences. A data acquisition computer, electrically connected to each pressure detection mechanism, receives and displays the information detected by the pressure detection mechanism and controls the hydraulic jacking mechanism based on this information. By arranging a ring of evenly distributed multi-point hydraulic testing devices around the pile shoe, the device is activated to pre-probe the soil bearing capacity before the pile shoe penetrates into a seabed soil layer with uncertain bearing capacity. This allows for the acquisition of the soil's withstand pressure and the identification of any "eggshell" shaped strata, thereby proactively identifying the risk of further pile shoe penetration under load.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration, and in particular to a hydraulic testing device and method for the bearing capacity of the bottom of a self-elevating drilling platform pile shoe. Background Technology

[0002] The jack-up platform is equipped with freely raising and lowering legs. During operation, the legs extend to the seabed, allowing the platform to stand upright. The legs support the platform, raising its bottom a certain distance above the sea surface to avoid the impact of waves and currents, thus enabling operations to be carried out on the platform. To ensure the stable and reliable operation of the jack-up platform, each leg must be pre-loaded. This ensures that the ballast penetrates into the soil layer capable of reliably withstanding the maximum design pre-load. This soil layer forms the bearing layer of the platform foundation, ensuring the stability of the platform foundation throughout the entire operation.

[0003] Due to the unique method of pile shoe insertion in jack-up platforms, which relies on a pile shoe structure with a certain area to "step" into the shallow soil layer of the seabed, it is a type of end-bearing pile structure that relies on the bottom end face to provide bearing capacity. Therefore, there are specific risks during the platform placement process. Depending on the differences in the strength of the seabed soil layers, the pile shoe may inevitably penetrate too deeply into the seabed soil during the ballast penetration process, resulting in insufficient pile leg length and difficulty in pile extraction. In addition, due to the differences in seabed soil properties, bearing capacity, and stability at different depths caused by seabed soil deposition conditions, for the end-bearing pile structure characteristics of jack-up drilling platforms, when standing briefly in a relatively hard soil layer, if the critical bearing capacity of the soil layer at that depth is exceeded, the pile leg may suddenly sink, leading to the risk of puncture.

[0004] "Perforation" refers to the phenomenon where, during preloading or normal operation of a jack-up drilling platform, the bearing stratum of the pile foundation supported by the seabed soil suddenly fails (shear slip or punching shear fracture) under the load applied by the massive pile legs, causing the pile legs to lose their unbalanced support and sink rapidly. Pile leg punctures can lead to platform tilting, damage to structural components, and even platform capsizing and sinking. Perforation is the greatest safety threat to jack-up drilling platforms and is prone to occur.

[0005] The existing approach to solving this problem involves towing the jack-up drilling platform to the designated target site for pile driving and ballast operations. Before this, a survey vessel drills holes at the pile driving location on the platform site to collect single-point samples. Soil mechanics tests are then conducted in the laboratory to obtain design parameters for the shear strength and other bearing capacity of the single soil layer. However, this method has drawbacks. The obtained parameters are non-in-situ bearing capacity. Sampling, preservation, and transportation processes involve soil disturbance or water loss, meaning the samples cannot truly represent the in-situ soil mechanical properties. Furthermore, typically only one or two borehole samples are taken from a single pile leg location, resulting in sparse sampling points and a small area. This makes it difficult to represent the overall bearing capacity of the soil at the pile shoe location, which can cover hundreds of square meters, and fails to reflect the lateral heterogeneity of the soil layer.

[0006] Alternatively, improvements can be made to the existing pile shoe structure. A common improvement is to increase the bearing area of ​​the pile shoe to give it higher bearing capacity. Under the same seawater ballast, the larger the pile shoe area, the lower the pressure exerted by the pile shoe on the seabed soil. When the pile shoe contacts a hard layer, the hard layer will support the larger pile shoe area with its own strength, thus preventing it from piercing the hard layer. If the hard layer is below a very thin layer of soft mud, the hard layer has poor stability. Increasing the bearing area of ​​the pile shoe can reduce the pressure on the soil at the bottom of the pile shoe, but it will make it difficult for the pile shoe to break through the thin hard layer under a relatively small ballast. Once the ballast increases to the ultimate ballast, the "eggshell" stratum composed of the thin hard layer and the underlying soft soil layer will be severely punctured. After puncture, the pile shoe will be at high risk under a large ballast. These types of pile shoes are not suitable for all hard soil layers where puncture is possible. When the hard soil layer does not reach the bearing capacity required by the pile shoe, puncture will still occur. In certain types of layered soil structures, increasing the pile shoe area may result in insufficient pressure on the thin, hard soil layer under low load conditions, while exceeding the bearing capacity of the thin, hard soil layer once the maximum load is reached. In this case, if puncture occurs, the consequences will be more severe, and the impact force during puncture will be greater. Therefore, increasing the pile shoe area in "eggshell" strata composed of thin, hard soil layers and thick, soft soil layers will result in greater puncture risk and subsequent damage. Summary of the Invention

[0007] To address the aforementioned problems, the first objective of this invention is to provide a hydraulic testing device and method for the bearing capacity of the bottom of a jack-up drilling platform's pile shoe. This device and method can proactively probe the bearing capacity of the soil at the bottom of the pile shoe throughout the entire process of preloading the jack-up platform to its maximum design load, thereby determining the pressure that the seabed soil at the bottom of the pile shoe can withstand during the ballast process and thus avoiding the risk of puncture. Secondly, this invention provides a hydraulic testing method for the bearing capacity of the bottom of a jack-up drilling platform's pile shoe.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a hydraulic testing device for the bearing capacity of the bottom of a self-elevating drilling platform pile shoe, comprising:

[0010] Several hydraulic jacking mechanisms are arranged at intervals along the circumferential direction of the pile shoe. Each hydraulic jacking mechanism is equipped with a pressure detection mechanism, which is used to detect the insertion depth of the pile shoe and the force applied.

[0011] A data acquisition computer, electrically connected to the pressure detection mechanism, is used to receive and display the information detected by the pressure detection mechanism, and to control the hydraulic lifting mechanism to operate based on the detected information.

[0012] Furthermore, several of the hydraulic lifting mechanisms are arranged in an array along the circumferential direction of the pile shoe.

[0013] Furthermore, the hydraulic lifting mechanism is a hydraulic jack.

[0014] Furthermore, the pressure detection mechanism is a pressure sensor.

[0015] Secondly, the present invention provides a hydraulic testing method for the bottom bearing capacity of a self-elevating drilling platform pile shoe, based on the aforementioned hydraulic testing device for the bottom bearing capacity of a self-elevating drilling platform pile shoe, comprising the following steps:

[0016] The drilling and production location is determined by GPS equipment, which confirms the heading and leg positions of the jack-up drilling platform.

[0017] Driven by the freely rising and falling pile legs, the pile shoe is lowered into the stratum. When the pile shoe reaches the depth of the hard stratum, loading is immediately stopped, the seawater in the ballast tank is drained, and the hydraulic jacking mechanism around the pile shoe is activated to conduct a pre-test of the bearing capacity of the hard stratum.

[0018] When it is determined that the bearing pressure of the hard stratum is sufficient to withstand the maximum preload of the self-elevating drilling platform, seawater is continuously poured into the ballast tank to carry out preload until the maximum design preload is reached.

[0019] When the preliminary exploration results of the hydraulic jacking mechanism on the hard strata are insufficient to support the bottom pressure of the pile shoe of the self-elevating drilling platform to continue ballasting, puncture risk response measures shall be implemented.

[0020] Furthermore, the measures to address the risks associated with puncture are as follows:

[0021] The hull is brought close to the sea surface or partially submerged in seawater to load draft.

[0022] Furthermore, the draft loading specifically involves pumping seawater into the ballast chambers inside the hull, using the weight of the seawater to press down the legs and shoes together, and adjusting the lifting system between the legs and the hull to keep the hull in a horizontal state during the ballast loading process until the ballast seawater volume reaches the maximum design ballast capacity of the corresponding jack-up drilling platform, at which point the ballast operation ends.

[0023] Furthermore, the measures to address the puncture risk are as follows: terminate the continued ballast piling operation and move the jack-up drilling platform away from the puncture risk area.

[0024] Furthermore, the specific method of lowering the pile shoe into the stratum is as follows: the hull is raised, the pile legs are subjected to the load of the hull's own weight, the load is transferred to the pile shoe, and the pile shoe is driven into the stratum under ballast.

[0025] Furthermore, the specific method of lowering the pile shoe into the strata is as follows: the weight of the ship combined with seawater ballast is used to lower the pile shoe into the seabed strata.

[0026] The present invention has the following advantages due to the adoption of the above technical solutions:

[0027] The hydraulic testing device for the bottom bearing capacity of the self-elevating drilling platform pile shoe provided in this invention uses a ring of evenly distributed multi-point or single-point hydraulic testing devices around the edge of the pile shoe. Before the pile shoe is subjected to ballast penetration into the seabed soil layer with uncertain bearing capacity, the hydraulic testing devices around the pile shoe are activated to actively probe the soil bearing capacity, i.e., the maximum pressure that the soil layer "stepped" on by the pile shoe can withstand. This obtains the magnitude of the soil's bearing capacity and identifies the presence of "eggshell" strata, thereby identifying the risk of the pile shoe continuing to penetrate under ballast in advance and avoiding the risk of the pile shoe penetrating too deeply or puncturing. This invention can prevent the pile shoe from suddenly sinking due to the nature of the strata when piercing hard strata, effectively solving the puncture risk caused by "eggshell" strata and allowing for advance countermeasures.

[0028] This invention employs a multi-point distributed hydraulic testing device, capable of breaking through "eggshell" strata. Specifically, through multi-point distributed hydraulic probing devices around the pile shoe, the ultimate bearing capacity of the thin, hard stratum "stepped" upon by the pile shoe is simultaneously probed, creating probing holes along the circumference of the pile shoe. With the structural integrity of the thin, hard stratum prematurely disrupted, its bearing capacity decreases, making it comparable to the bearing capacity of the underlying soft stratum. At this point, the self-elevating drilling platform's legs, connected to the pile shoe, can penetrate into the soft stratum beneath the thin, hard stratum in a relatively stable manner under low or even light load conditions. This avoids sudden shear failure of the initially intact thin, hard stratum under high platform loads, preventing punctures to the platform's legs.

[0029] In this invention, when the pre-exploration results of the hard stratum are insufficient to support the bottom pressure of the pile shoe of the jack-up drilling platform to continue ballasting, the jack-up drilling platform hull is kept in a floating state, i.e., draft ballasting, which helps the pile shoe in the seabed soil layer to smoothly pass through the thin hard stratum until the pile shoe is lowered to the designated position or a safe depth with sufficient bearing capacity, thereby avoiding the risk of pile puncture in the thin hard stratum ("eggshell" stratum). Attached Figure Description

[0030] Figure 1 This is a diagram showing the bow direction and leg positions of a jack-up drilling platform.

[0031] Figure 2 This is a schematic diagram of the hydraulic testing device for the bearing capacity of the bottom of the pile shoe of a self-elevating drilling platform provided in an embodiment of the present invention;

[0032] Figure 3 A diagram showing the drilling status of a self-elevating drilling platform equipped with the aforementioned hydraulic testing device;

[0033] Explanation of reference numerals in the attached figures:

[0034] 1-Pile leg, 2-Pile shoe, 3-Hydraulic jacking mechanism, 4-Self-elevating drilling platform. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0036] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., used to define components are merely for the convenience of distinguishing the aforementioned components. Unless otherwise stated, these terms have no special meaning and should not be construed as indicating or implying relative importance.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] The present invention provides a hydraulic testing device for the bottom bearing capacity of a self-elevating drilling platform pile shoe, which is used to actively pre-probe the bearing capacity of the seabed soil near the bottom of the pile shoe 2, thereby actively identifying the "eggshell" stratum. It also has the ability to actively break through the "eggshell" stratum, avoiding the risk of pile puncture when encountering the "eggshell" stratum, reducing the unstable bearing capacity of the "eggshell" stratum which is prone to brittle failure, and helping the pile shoe to safely penetrate the "eggshell" stratum under light load conditions. It avoids the platform instability or damage caused by sudden puncture when the pile shoe is blocked and a large load is applied.

[0039] Combination Figure 1 , Figure 2 as well as Figure 3 As shown, the hydraulic testing device for the bearing capacity of the bottom of the pile shoe of the self-elevating drilling platform includes several hydraulic jacking mechanisms 3, an HVC force controller, hydraulic and data transmission cables, and a data acquisition computer. The several hydraulic jacking mechanisms 3 are arranged in an array along the circumferential direction of the pile shoe 2 of the self-elevating drilling platform 4.

[0040] Each of the hydraulic jacking mechanisms 3 is equipped with a pressure detection mechanism, which is used to detect the insertion depth and stress of the pile shoe 2.

[0041] The pressure detection mechanism can be a pressure sensor. The pressure sensor sends the detected signal to the HVC force controller, which converts the detected analog signal into a digital signal and sends it to the data acquisition computer. The data acquisition computer and the HVC force controller are connected via the hydraulic and data transmission cable. The computer receives and displays the detected digital signal and sends control commands to the HVC force controller based on the detected digital signal. The HVC force controller then controls the operation of the pressure hydraulic lifting mechanism 3.

[0042] The hydraulic lifting mechanism 3 is preferably a hydraulic jack.

[0043] The hydraulic jack is preferably positioned on the outer edge of the pile shoe 2.

[0044] It should be noted that the interval between two adjacent hydraulic jacks can be adjusted as needed.

[0045] The testing method based on the hydraulic testing device for the bearing capacity of the bottom of the pile shoe of the self-elevating drilling platform includes the following steps:

[0046] like Figure 1 As shown, the drilling and production location is determined by GPS equipment, confirming the heading of the jack-up drilling platform 4 and the position of the legs 1.

[0047] S1. Pile shoe 2 is lowered. During the lowering process, the stress and depth of each pile leg 1 are monitored in real time, as well as the levelness of the platform. When the pile shoe 2 reaches the hard stratum, the lowering stops, loading is immediately suspended, the seawater in the ballast tank is drained, and the hydraulic jacking mechanism around the pile shoe 2 is activated to pre-test the bearing capacity of the hard stratum. If it is determined that the bearing pressure of the hard stratum is sufficient to withstand the maximum pre-ballast load of the self-elevating drilling platform 4, the pressure of the pile shoe on the soil is then increased. Seawater is pumped into the ballast tank through a water pump to implement pre-ballast until the maximum design pre-ballast load is reached. The pile shoe can be lowered solely by the weight of the hull, or by a combination of the hull weight and seawater ballast. However, the pre-ballast during pile shoe lowering is always a light-load pre-ballast.

[0048] When the preliminary exploration results of the aforementioned hydraulic jacking mechanism for hard strata are insufficient to support the bottom pressure of the pile shoe 2 of the self-elevating drilling platform 4 for continued ballast loading, puncture risk response measures shall be implemented or the risk of further loading shall be assessed.

[0049] The measures to address the risks associated with puncture are as follows:

[0050] To ensure the hull bottom is close to the sea surface or partially submerged, if the designated depth cannot be reached by its own weight, draft loading can be used. Draft loading increases the platform's own weight, further pressing down the pile shoes 2 until a hard stratum sufficient to withstand the maximum pre-ballast load of the jack-up drilling platform is reached, and the ballast is applied up to the maximum design pre-ballast capacity. Draft ballast also involves filling the ballast tanks with seawater. However, during draft ballast operations, there is no air gap between the hull bottom and the sea surface; the hull floats on the sea surface with very little buoyancy. Most of the force is balanced by the support of the pile legs. Under draft ballast conditions, as the amount of seawater in the ballast tanks increases, the load on the pile legs continuously increases, transferring to the pile shoes connected to the bottom of the pile legs, thus ballasting the formation. Once the ballast exceeds the bearing capacity of the stratum and a puncture occurs, the pile legs sink instantly. The hull loses the support of the pile legs and sinks instantly along with them. The volume of water displaced by the hull also increases instantly, increasing the buoyancy of the hull and preventing the hull and pile legs from sinking further. This reduces the sinking distance of the hull on one side of the single pile leg that is under ballast caused by the puncture, reduces the tilt angle of the hull, and effectively prevents the platform pile legs from bending and the connection between the pile legs and the platform from being damaged.

[0051] In this invention, by using draft loading, once the platform is punctured, the volume of seawater displaced by the hull rapidly increases as the hull sinks quickly. This rapidly increases the buoyancy of the seawater on the entire platform, using buoyancy to balance the tilt caused by the "eggshell" strata, preventing the hull from capsizing or being damaged by the hull and pile legs. The preloading of the other two pile legs is completed in the same way.

[0052] Alternatively, as another approach, the risk mitigation measures for puncture can be implemented by terminating the continued pile driving and ballast operations.

[0053] The hydraulic testing device for the bearing capacity of the bottom of the self-elevating drilling platform pile shoe provided in this invention uses a multi-point hydraulic jacking mechanism evenly distributed around the edge of the pile shoe 2. Before the pile shoe 2 is ballasted into the seabed soil layer with uncertain bearing capacity, the hydraulic jacking mechanism around the pile shoe 2 is activated to conduct a preliminary exploration of the soil bearing capacity, obtain the pressure that the soil can bear, and identify whether there is an "eggshell" type stratum. This allows for early identification of the risk of the pile shoe 2 continuing to ballast and avoids the risk of the pile shoe 2 penetrating too deeply or puncturing.

[0054] The hydraulic testing device for the bearing capacity of the bottom of the pile shoe of the self-elevating drilling platform provided by the present invention avoids the objective limitations of conventional engineering geological drilling and sampling and obtaining the design parameters of seabed soil bearing capacity through indoor soil mechanics tests, such as the single data point and the disturbance of soil sampling and testing process, which leads to the distortion or loss of test data.

[0055] This invention avoids the puncture phenomenon of the self-elevating platform's pile shoe 2, and can increase the lowering speed during the pile shoe 2 lowering process, thereby improving on-site operation efficiency. It also avoids the risk of platform overturning due to sudden puncture of the pile shoe 2, thus preventing personnel casualties.

[0056] This method can also effectively reduce the platform damage rate, and reduce maintenance costs and time costs.

[0057] 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 hydraulic testing device for the bearing capacity of the bottom of a self-elevating drilling platform pile shoe, characterized in that, include: Several hydraulic jacking mechanisms are arranged at intervals along the circumferential direction of the pile shoe. Each hydraulic jacking mechanism is equipped with a pressure detection mechanism, which is used to detect the insertion depth of the pile shoe and the force applied. A data acquisition computer, electrically connected to the pressure detection mechanism, is used to receive and display the information detected by the pressure detection mechanism, and control the hydraulic lifting mechanism to operate based on the detected information; Several of the hydraulic lifting mechanisms are arranged in an array along the circumferential direction of the pile shoe; The hydraulic lifting mechanism is a hydraulic jack; The pressure detection mechanism is a pressure sensor; Before the pile shoe is ballasted into the seabed soil layer with uncertain bearing capacity, the hydraulic jacking mechanism around the pile shoe is activated to conduct a preliminary exploration of the soil bearing capacity, obtain the pressure that the soil can bear, and identify whether there is an eggshell-like stratum. This allows for early identification of the risk of the pile shoe continuing to ballast and avoids the risk of the pile shoe penetrating too deeply or puncturing. Configure to perform the following steps: The drilling and production location is determined by GPS equipment, which confirms the heading and leg positions of the jack-up drilling platform. The pile shoe is driven into the stratum. When the pile shoe reaches the depth of the hard stratum, loading is immediately paused and the hydraulic jacking mechanism around the pile shoe is activated to pre-probe the bearing capacity of the hard stratum. When it is determined that the bearing pressure of the hard stratum is sufficient to withstand the maximum preload of the self-elevating drilling platform, seawater is continuously poured into the ballast tank to carry out preload until the maximum design preload is reached. When the preliminary exploration results of the hydraulic jacking mechanism for hard strata are insufficient to support the bottom pressure of the pile shoe of the self-elevating drilling platform to continue ballasting, puncture risk response measures shall be implemented. The bottom of the hull is brought close to the sea surface or part of the hull is submerged in seawater. If the hull has not reached the specified depth by its own weight, the draft loading method is used to load the platform. The draft loading increases the platform's own weight and continues to press the pile shoe down until it reaches a hard stratum that can withstand the pressure at the bottom of the pile shoe, which is sufficient to bear the maximum preload of the self-elevating drilling platform, and then loads it to the maximum design preload.

2. The hydraulic testing device for the bearing capacity of the bottom of the pile shoe of a self-elevating drilling platform according to claim 1, characterized in that, The measures to address the risks associated with puncture are as follows: The hull is brought close to the sea surface or partially submerged in seawater to load draft.

3. The hydraulic testing device for the bearing capacity of the bottom of the pile shoe of a self-elevating drilling platform according to claim 2, characterized in that, The draft loading process specifically involves pumping seawater into the ballast chambers inside the hull, using the weight of the seawater to press down the legs and shoe together, and adjusting the lifting system between the legs and the hull to keep the hull in a horizontal position during the ballast loading process until the ballast seawater volume reaches the maximum design ballast capacity of the corresponding jack-up drilling platform, at which point the ballast operation is completed.

4. The hydraulic testing device for the bearing capacity of the bottom of the pile shoe of a self-elevating drilling platform according to claim 1, characterized in that, The measures to address the puncture risk are as follows: terminate the continued ballast pile driving operation and move the jack-up drilling platform away from the puncture risk area.

5. The hydraulic testing device for the bearing capacity of the bottom of the pile shoe of a self-elevating drilling platform according to claim 1, characterized in that, The specific process of lowering the pile shoe into the stratum involves: raising the hull, subjecting the pile legs to the hull's own weight, transferring the load to the pile shoe, and ballasting the pile shoe as it penetrates into the stratum.

6. The hydraulic testing device for the bearing capacity of the bottom of the pile shoe of a self-elevating drilling platform according to claim 5, characterized in that, The specific method of lowering the pile shoe into the strata is as follows: the weight of the ship combined with seawater ballast is used to lower the pile shoe into the seabed strata.

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