A design method for repairing old pile shoe pits in the positioning operation area

Abstract

This invention provides a design method for repairing old pile shoe pits in the positioning operation area, belonging to the field of oil drilling. The steps include drawing a special hull drawing for positioning design; drawing a special platform drawing for positioning based on the jacket or platform design drawings; drawing a special pipeline and cable drawing for positioning based on the pipeline and cable design drawings; drawing a plan view of the pile shoe pits from the data of the previous pile shoe pit groups; and drawing a preliminary design drawing of the positioning scheme based on the selection factors. This invention helps self-elevating platforms to repair footprints in repeated positioning positions and multiple sets of drilling platform pile shoe pit positions, reducing the lateral slip force, slippage amount, and slippage trend of the piles, and plays an important role in protecting large offshore facilities from collisions and in oilfield development.

Description

Technical Field

[0001] This invention belongs to the field of oil drilling, and in particular relates to a design method for repairing old pile shoe pits in the positioning operation area. Background Technology

[0002] The use of jack-up drilling rigs for development and adjustment well operations has accelerated the oilfield development process. During the positioning and piling operations of jack-up drilling rigs, several challenges arise. First, soil conditions and the instability of the surface soil at the positioning site cause slippage. Second, factors such as the numerous wellhead coverage requirements of cluster wells, piling capacity, drilling rig schedules, and actual operational progress mean that multiple jack-up drilling rigs of different types and piling shoe diameters are positioned on the same production platform, creating pile shoe pits of varying sizes, depths, and distributions in the positioning area. Subsequent piling operations are also affected by the old piling shoe pits left from previous operations and the formation soil conditions, leading to slippage again, with a more significant and greater risk. Furthermore, the oilfield development schedule, drilling rig schedules, and operational plans can result in unreasonable rig selection and arrangement; mismatched rigs further increase the risk of positioning slippage. Slippage is a complex situation during positioning operations. The main cause of slippage loads is the asymmetry of the soil failure surface during pile shoe penetration. This leads to torque separation between the pile legs and the hull during pile driving, triggering RPD alarms and preventing further pile driving, ballasting, and hull lifting / lowering. This damages the pile legs and lifting mechanism. Positioning slippage significantly increases positioning operation time, sometimes by more than a week or even 10 days beyond the planned time. Slippage also affects the coverage of the cantilever beams on jack-up drilling platforms, resulting in incomplete wellhead coverage and impacting operational and oilfield development plans.

[0003] Existing technology involves multiple attempts to position the drilling platform at the designed location while ensuring coverage, followed by repeated piling and ballast loading. This results in platform slippage; slippage away from the docking point leads to incomplete coverage, while slippage close to the docking point poses a collision risk. Ultimately, this results in unsatisfactory positioning, failing to meet on-site operational requirements and impacting the oilfield development process. Invention Content

[0004] In view of this, the present invention aims to propose a design method for repairing old pile shoe pits in the positioning operation area, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0006] A design method for repairing old pile shoe pits in a positioning operation area, wherein the positioning operation area contains previous pile shoe pit groups for constructing an offshore jack-up platform, each previous pile shoe pit group including one previous bow pile pit and two previous stern pile pits arranged correspondingly; the method is based on setting a current pile shoe pit group for constructing an offshore jack-up platform within the positioning operation area, the current pile shoe pit group including one current bow pile pit and two current stern pile pits, and includes the following steps:

[0007] Step 1: Draw a special hull drawing for the positioning design based on the design drawings of the self-elevating platform, the ship handling manual, and research data;

[0008] Step 2: Draw a dedicated platform drawing for placement based on the jacket or platform design drawings;

[0009] Step 3: Draw the installation diagram of the dedicated pipeline and cable system based on the pipeline and cable design drawings;

[0010] Step 4: Draw the data of each pile shoe pit group into a plan view of each pile shoe pit;

[0011] Step 5: Draw a preliminary design drawing of the placement scheme based on the selection factors, including coverage requirements, predicted pile driving depth, water depth, drilling load requirements, and air gap for lifting the vessel; the preliminary design drawing of the placement scheme includes the hull of the dedicated placement design vessel. Figure 1 Dedicated positioning platform Figure 2 Dedicated pipeline and cable for positioning Figure 3 and the plane of each pile shoe pit Figure 4 ;

[0012] Step 6: Compare the overlap ratio of the current pile shoe imprint with the previous pile shoe imprints, and create a pile shoe imprint overlap ratio comparison table.

[0013] Step 7: Compare the predicted mud penetration depth of the drilling platform in this deployment with the mud penetration depth of different drilling platforms in previous deployments, and make a comparison table of mud penetration depth values ​​for pile driving.

[0014] Step 8: Compare the positioning time of the drilling platform this time with the positioning time of different drilling platforms in the past, and make a positioning time comparison table;

[0015] Step 9: Based on the comparison table of pile shoe imprint overlap ratio, pile insertion depth value comparison table and placement time comparison table obtained in steps 6 to 8, select a bow pile pit with repair conditions among the previous bow pile pits; or select a stern pile pit with repair conditions among the two previous stern pile pits.

[0016] Step 10: If the selected stern pile pit mentioned in step 9 is set as the bow pile pit for this repair, then the selected stern pile pit can be any of the previous stern pile pits.

[0017] Step 11: If the selected stern pile pit mentioned in step 9 is set as a current stern pile pit for repair, then the other current stern pile pit will not be repaired using the other previous stern pile pit corresponding to the selected stern pile pit.

[0018] Compared with existing technologies, the design method for repairing old pile shoe pits in the positioning operation area described in this invention has the following advantages:

[0019] (1) This invention proposes a design method for repairing old pile shoe pits in the positioning operation area, which helps to repair the footprints of self-elevating platforms in repeated positioning positions and multiple sets of drilling platform pile shoe pit positions, reduce the lateral sliding force, sliding amount and sliding trend of pile insertion, and plays an important role in protecting large offshore facilities from collisions and in oilfield development.

[0020] (2) The invention can use single piles to repair the pile shoe pits of previous times, expand the range of the pile shoe pits, which is beneficial to reduce the lateral sliding force when the drilling platform is inserted into the pile during this positioning and reduce the amount of slippage; it can prevent the drilling platform from repeatedly inserting piles back and forth in the final positioning design position, avoiding the risk of collision with the platform caused by slippage; and the repaired pile shoe pits of previous times are more conducive to the pile insertion and positioning, which can improve the positioning efficiency and success rate and promote the oilfield development process. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0022] Figure 1 The in-situ design hull drawing described in the embodiments of the present invention;

[0023] Figure 2 This is a schematic diagram of the dedicated positioning platform described in an embodiment of the present invention;

[0024] Figure 3 The diagram shows the dedicated pipeline and cable for placement as described in the embodiments of the present invention;

[0025] Figure 4 Plan views of the various pile shoe pits described in the embodiments of the present invention;

[0026] Figure 5 This is a preliminary design drawing of the positioning scheme described in an embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram illustrating the selected stern pile pit as used in the current bow pile pit repair in an embodiment of the present invention.

[0028] Figure 7 The selected stern pile pit described in the embodiment of the present invention is set as a schematic diagram of the current stern pile pit being repaired;

[0029] Figure 8 This is a preliminary design drawing of the positioning scheme described in an embodiment of the present invention;

[0030] Figure 9 Design drawings of the bow pile boot pit repair scheme described in the embodiments of the present invention;

[0031] Figure 10 The present invention provides a comparison table of pile shoe overlap ratio, pile insertion depth, and placement time as described in the embodiments of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1-Designed hull drawing for positioning; 2-Designated platform drawing for positioning; 3-Designated pipeline and cable drawing for positioning; 4-Plan view of previous pile shoe pits; 101-Hull outline; 102-Anchorage hole; 103-Cantilever beam coverage area; 104-Stern protrusion; 105-Pile shoe; 106-Hull centerline; 201-Top deck outline; 202-Living area; 203-Helicopter deck; 204-Cranial; 205-Square slot area; 206-Flame; 207-Apology; 601-; 602-Previous stern pile pits; 603-Current bow pile pit; 604-Current stern pile pit. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0035] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] A method for renovating old pile shoe pits in a positioning operation area, wherein the positioning operation area contains a group of previous pile shoe pits used for constructing an offshore jack-up platform, the group of previous pile shoe pits including one previous bow pile pit 601 and two previous stern pile pits 602 arranged corresponding to each other; the method is based on setting a current pile shoe pit group for constructing an offshore jack-up platform in the positioning operation area, the current pile shoe pit group including one current bow pile pit 603 and two current stern pile pits 604, and includes the following steps:

[0037] Step 1: Draw a dedicated hull drawing for the positioning design based on the design drawings, ship handling manual, and research data of the jack-up platform; the dedicated hull drawing for the positioning design, such as... Figure 1 As shown; the in-situ design of the special hull described in step 1. Figure 1 The figure includes: hull outline 101, pile shoe 105, cantilever beam coverage area 103 and stern protrusion 104; the figure also includes anchor hole 102 and hull centerline 106.

[0038] Step 2: Draw a dedicated positioning platform drawing based on the guide frame or platform design drawings; the dedicated positioning platform drawing, such as... Figure 2 As shown; the dedicated positioning platform mentioned in step 2 Figure 2 The diagram includes: top deck outline 201, living area 202, helicopter deck 203, crane 204, square slot area 205, flare 206, and azimuth angle 207;

[0039] Step 3: Draw the installation-specific pipeline and cable diagram based on the pipeline and cable design drawings; the installation-specific pipeline and cable diagram is as follows: Figure 3 As shown; the dedicated installation pipeline and cable mentioned in step 3 Figure 3 The diagram includes: a cable trajectory line formed by dots, with the direction and cable name marked;

[0040] Step 4: Draw the data of each pile shoe pit group into a plan view of each pile shoe pit; the plan view of each pile shoe pit is as follows: Figure 4 As shown; the plan view of each pile shoe pit mentioned in step 4 includes: the outline of each pile shoe 401 and the actual pile insertion depth value 402.

[0041] Step 5: Draw a preliminary design drawing of the placement scheme based on the selection factors, including coverage requirements, predicted pile depth, water depth, drilling load requirements, and air gap for lifting the vessel; the preliminary design drawing of the placement scheme is as follows: Figure 5 As shown; the preliminary design drawing of the positioning scheme includes the dedicated hull for the positioning design. Figure 1 Dedicated positioning platform Figure 2 and dedicated pipeline cables for positioning Figure 3 ;

[0042] Furthermore, the covering requirements mentioned in step 5 are specified by the operator; the predicted pile depth is obtained by borehole sampling, soil testing and calculation; the drilling load is determined by the load corresponding to the longitudinal and lateral extension distances of the turntable center when covering the well site; and the lift air gap requirements are determined by the top deck and top deck obstacles.

[0043] Step 6: Compare the overlap ratio of the current pile shoe imprint with the previous pile shoe imprints, and make a pile shoe imprint overlap ratio comparison table; In Step 6, the overlap ratio is the ratio of the area of ​​the current pile shoe imprint to the area of ​​the previous pile shoe imprints, and the overlap ratio shown increases by 10%.

[0044] Step 7: Compare the predicted mud penetration depth of the drilling platform in this deployment with the mud penetration depth values ​​of different drilling platforms in previous deployments, and create a comparison table of mud penetration depth values, such as... Figure 10 As shown; in step 7, the predicted mud penetration depth is calculated based on borehole sampling and soil testing, yielding the theoretical depth of the drilling platform in place. The formula for calculating the theoretical depth is as follows:

[0045] Q = q n A+γ1V+fAs

[0046] In the formula:

[0047] A s = Lateral surface area of ​​the pile foundation mud

[0048] f = unit surface friction

[0049] qn = Ultimate bearing capacity per unit area of ​​pile foot

[0050] A = Maximum cross-sectional area of ​​the pile foot

[0051] γ1 = Average effective unit weight of soil discharged from pile toe

[0052] V = Volume of soil displaced by the pile base

[0053] Step 8: Compare the placement time of the drilling platform this time with the placement time of different drilling platforms in the past, and create a placement time comparison table, such as... Figure 10 As shown;

[0054] Step 9: Based on the comparison table of pile shoe imprint overlap ratio, pile insertion depth in mud value comparison table, and placement time comparison table obtained in steps 6 to 8, select a bow pile pit with repair conditions among the previous bow pile pits 601; or select a stern pile pit with repair conditions among the two previous stern pile pits 602.

[0055] Furthermore, the selected stern pile pit with the conditions for repair described in step 9 meets one of the following characteristics: Characteristic 1: The overlap ratio between the pile shoe imprint of this placement and all previous pile shoe pits is relatively small; Characteristic 2: The pile insertion depth of a certain group of previous pile shoe pits is relatively deep; Characteristic 3: The placement time of a certain group of previous pile shoe pits is closest to that of this placement; Characteristic 4: The relative difference between the predicted depth value of the drilling platform in this placement and the depth of a certain group of previous pile shoe pits is the smallest.

[0056] Step 10: If the selected stern pile pit mentioned in Step 9 is set as the bow pile pit 603 for this repair, then the selected stern pile pit is any one of the previous stern pile pits 602; Figure 6 As shown, the current bow pile pit 603 is used to install the bow pile, which is the bow leg of the self-elevating platform vessel; the previous stern pile pits 602 are the two legs of the stern of the self-elevating platform vessel, which can be divided into the previous left stern pile and the previous right stern pile.

[0057] Step 11: If the selected stern pile pit described in Step 9 is set as a current stern pile pit 604 for repair, then the other current stern pile pit 604 will not be repaired using the other previous stern pile pit 602 corresponding to the selected stern pile pit; such as Figure 7 As shown;

[0058] Further explanation of this invention is needed regarding the following: In the above-mentioned modification design method, the survey data mentioned in step 1 refers to the data obtained from a physical survey of the jack-up platform while it is in the dry dock, which facilitates the identification of modifications to the jack-up platform and areas differing from the design drawings; the dedicated hull drawing, the dedicated platform drawing, the dedicated pipeline and cable drawing, and the pile shoe pit plan are standard drawings used for designing the jack-up platform positioning scheme; steps 1 to 11 are designed according to the offshore jack-up platform positioning specifications; in steps 10 and 11, when designing the scheme for the two old pile shoe pit modification methods, there are instances where the pile insertion modification position of the drilling platform is appropriately adjusted. The modification mentioned in steps 10 and 11 is a single pile modification.

[0059] In a further preferred embodiment of the invention: the previously identified pile shoe pit group does not include previously identified pile shoe pits formed more than 10 years after the current placement time; the analysis results do not consider old pile shoe pits whose formation time is more than 10 years after the current placement time. In another preferred embodiment of the invention: the analysis results do not consider old pile shoe pits with an overlap ratio of less than 10% and a mud penetration depth of less than 3 meters with the current placement pile shoe pit. The drawing in steps 1 to 5, 10, and 11 is all performed in AutoCAD software and generated as DWG format files. Steps 1 to 11 are designed according to the offshore jack-up platform placement specifications.

[0060] The following specific embodiment further illustrates a design method for repairing old pile shoe pits in the positioning operation area according to the present invention, including the following steps:

[0061] Following step 1, draw the hull diagram for this in-situ design—the hull diagram of the Haiyang Shiyou 924 vessel; as follows: Figure 1 As shown, the centerline of the self-elevating platform hull is a design auxiliary line, and the bow direction is marked on the centerline of the hull.

[0062] Following step 2, draw the dedicated platform diagram—a top view of the BZ26-3-B platform; as shown... Figure 2 As shown, the azimuth is the angle between the platform's north direction and true north direction;

[0063] Following step 3, draw the installation diagram of the dedicated pipeline and cable system based on the pipeline and cable design drawings, such as... Figure 3 As shown, the BZ26-3-B platform includes one water injection pipeline 301 from BZ36-3-B to BZ26-3-A platform, one mixed transport pipeline 302 from BZ26-3-B to BZ26-3-A platform, and one submarine cable 303 from BZ26-3-B to BZ26-3-A platform.

[0064] Following step 4, there were two sets of old pile shoe pits before the current HYSY924 was installed. These were drawn as a plan view of the pile shoe pits from previous installations, as shown below. Figure 4 As shown, these are the Bohai No. 12 and Bohai No. 10 self-elevating platforms, respectively.

[0065] Following step 5, based on selection factors such as coverage requirements, predicted pile depth, water depth, drilling load requirements, and air gap requirements for lifting the vessel, a placement scheme design is carried out, and a preliminary design drawing of the placement scheme is produced, as follows: Figure 8 As shown;

[0066] Following steps 6 to 8, create comparison tables for the overlap ratio of pile shoe imprints, the depth of pile insertion into the mud, and the placement time, as follows: Figure 10 As shown in the figure, the overlap ratio refers to the overlap ratio of the pile shoe imprints, and the pile insertion depth refers to the depth of the pile into the mud. The data corresponding to HYSY924 in the figure represents the current pile shoe pit group, and the data corresponding to Bohai No. 10 and Bohai No. 12 represent previous pile shoe pit groups.

[0067] Following steps 9 to 11, based on the comparison tables of pile shoe imprint overlap ratio, pile insertion depth, and placement time, the analysis results show that Bohai No. 10 has the most recent placement time, the deepest pile insertion, and a smaller overlap ratio of the bow pile shoe imprint. Therefore, the stern pile pit is selected as the bow pile pit for this project, and a design scheme is developed. A bow pile shoe pit repair scheme design is then implemented based on the analysis results. The bow pile shoe pit repair scheme design drawing is shown below. Figure 9 As shown, the Bohai No. 10 was the most recently positioned, has the deepest pile driving, and has a relatively small overlap of the bow pile's pile shoe imprints. Therefore, the bow pile was selected as the target for repair and a design scheme was developed.

[0068] This invention helps to reduce the lateral slippage force and the amount of slippage when the drilling platform is driven into position; it prevents the drilling platform from repeatedly driving into position back and forth at the final design position, avoiding the risk of collision with the platform caused by slippage; and the modified pile shoe pits are more conducive to the driving into position, which can improve the driving efficiency and success rate.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for renovating old pile shoe pits in a positioning operation area, wherein the positioning operation area contains a group of previous pile shoe pits used for constructing an offshore jack-up platform, the group of previous pile shoe pits comprising one previous bow pile pit and two previous stern pile pits arranged corresponding to each other; the method is based on setting a current pile shoe pit group for constructing an offshore jack-up platform within the positioning operation area, the current pile shoe pit group comprising one current bow pile pit and two current stern pile pits, characterized in that, Includes the following steps: Step 1: Draw a special hull drawing for the positioning design based on the design drawings of the self-elevating platform, the ship handling manual, and research data; Step 2: Draw a dedicated platform drawing for placement based on the jacket or platform design drawings; Step 3: Draw the installation diagram of the dedicated pipeline and cable system based on the pipeline and cable design drawings; Step 4: Draw the data of each pile shoe pit group into a plan view of each pile shoe pit; Step 5: Draw a preliminary design drawing of the placement scheme based on the selection factors, which include coverage requirements, predicted pile driving depth, water depth, drilling load requirements, and air gap for lifting the vessel; the preliminary design drawing of the placement scheme includes a hull drawing of the dedicated placement design vessel, a dedicated placement platform drawing, a dedicated placement pipeline and cable drawing, and a plan view of each pile shoe pit. Step 6: Compare the overlap ratio of the current pile shoe imprint with the previous pile shoe imprints, and create a pile shoe imprint overlap ratio comparison table. Step 7: Compare the predicted mud penetration depth of the drilling platform in this deployment with the mud penetration depth of different drilling platforms in previous deployments, and make a comparison table of mud penetration depth values ​​for pile driving. Step 8: Compare the positioning time of the drilling platform this time with the positioning time of different drilling platforms in the past, and make a positioning time comparison table; Step 9: Based on the comparison table of pile shoe imprint overlap ratio, pile insertion depth value comparison table and placement time comparison table obtained in steps 6 to 8, select a bow pile pit with repair conditions among the previous bow pile pits; or select a stern pile pit with repair conditions among the two previous stern pile pits. Step 10: If the selected stern pile pit mentioned in step 9 is set as the bow pile pit for this repair, then the selected stern pile pit can be any of the previous stern pile pits. Step 11: If the selected stern pile pit mentioned in step 9 is set as a current stern pile pit for repair, then the other current stern pile pit will not be repaired using the other previous stern pile pit corresponding to the selected stern pile pit. The selected stern pile pit with the conditions for repair described in step 9 meets one of the following characteristics: Characteristic 1: The overlap ratio between the pile shoe imprint of this placement and all previous pile shoe pits is relatively small; Characteristic 2: The pile insertion depth of a certain group of previous pile shoe pits is relatively deep; Characteristic 3: The placement time of a certain group of previous pile shoe pits is closest to that of this placement; Characteristic 4: The relative difference between the predicted depth value of the drilling platform in this placement and the depth of a certain group of previous pile shoe pits is the smallest. The hull drawing for positioning design described in Step 1 includes: hull outline, pile shoe, cantilever beam coverage area, and stern protrusion; the platform drawing for positioning described in Step 2 includes: top deck outline, azimuth, slot area, flare, workover rig, crane, and living quarters; the pipeline and cable drawing for positioning described in Step 3 includes: the pipeline and cable trajectory line formed by the dotted records, with the direction and pipeline / cable name marked; the plan view of each pile shoe pit described in Step 4 includes: pile shoe outline and actual pile insertion depth. The repairs described in steps 10 and 11 are single-pile repairs.

2. The method for repairing old pile shoe pits in the positioning operation area according to claim 1, characterized in that: In step 5, the covering requirements are specified by the operator; the predicted pile depth is obtained by borehole sampling, soil testing and calculation; the drilling load is determined by the load corresponding to the longitudinal and lateral extension distances of the turntable center when covering the well site; and the lift air gap requirements are determined by the top deck and top deck obstacles.

3. The method for repairing old pile shoe pits in the positioning operation area according to claim 1, characterized in that: In step 6, the overlap ratio is the ratio of the overlap area to the area of ​​the pile shoe imprint in this placement, and the overlap ratio increases by 10% in increments.

4. The method for repairing old pile shoe pits in the positioning operation area according to claim 1, characterized in that: In step 7, the predicted mud penetration depth is calculated based on borehole sampling and soil testing to determine the theoretical depth of the drilling platform in place for this operation.

5. The method for repairing old pile shoe pits in the positioning operation area according to claim 1, characterized in that: The previously mentioned pile shoe pit group does not include any pile shoe pits formed more than 10 years after the current placement.

6. The design method for repairing old pile shoe pits in the positioning operation area according to claim 1, characterized in that: The drawing described in steps 1 to 5, 10 and 11 is all performed in AutoCAD software and forms a dwg format file.

7. The method for repairing old pile shoe pits in the positioning operation area according to claim 1, characterized in that: Steps 1 to 11 are designed in accordance with the offshore jack-up platform positioning specifications.

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