Self-elevating platform pile pitching operation slippage semi-quantitative judgment method

Abstract

The invention discloses a self-elevating platform pile pitching operation slippage semi-quantitative judgment method which comprises the following steps: investigating the form of an old pile pit; old pile pit survey parameters are analyzed; a self-elevating platform in-place scheme is designed, and the position of the self-elevating platform is determined; judging the area coincidence ratio of the pile shoe to the old pile pit; analyzing the slope degree of the old pile pit and performing collapse backfilling; analyzing the pile center distance; the comparison value of the pile shoe diameter of the in-place pile pitching self-elevating platform and the old pile pit and the comparison value of the predicted depth and the depth of the old pile pit are determined; analyzing the self-weight and the full-load ballast of the self-elevating platform; analyzing the overall slippage trend of the three piles; forming an instrumentation slip influence factor and slip risk grade table; and a slip semi-quantitative determination result is obtained. The self-elevating platform multi-time pile pitching operation slippage risk judgment, pile pitching operation safety early warning and pile pitching operation plan making are facilitated, the in-place pile pitching operation safety of the self-elevating platform is guaranteed, the slippage risk is reduced to the maximum degree, the safety of large facilities and personnel is guaranteed, and the offshore oilfield development process is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of pile-insertion operation of a self-elevating platform in an offshore oil field, and in particular relates to a semi-quantitative determination method for slippage in pile-insertion operation of a self-elevating platform. Background Art

[0002] As the volume of offshore oilfield exploration and development operations continues to rise, the use of jack-up platforms for development wells and adjustment wells is the main mode of offshore development operations. During the jack-up platform's in-place piling operation, on the one hand, it is affected by the soil quality, that is, whether it is original soil or reshaped soil, its surface soil has a certain instability, which leads to slippage during the jack-up platform's piling process. On the other hand, due to the different operating capabilities of different jack-up platforms, combined with actual operating requirements, drilling rig plans and other factors, the same production platform will have multiple jack-up platforms of different types and different pile shoe diameters in place, forming pile shoe pits of different array sizes, depths, and distributions in the piling area. When the piling operation is carried out again, slippage will also occur due to the influence of the old pile shoe pits left by the previous operations and the soil quality of the formation, and the risk of slippage is greater. In addition, during the selection of jack-up platforms, affected by the progress of oilfield development, drilling rig plans and operation plans, the drilling platform and the production platform cannot be reasonably matched, increasing the risk of slippage during the jack-up platform's in-place piling.

[0003] The existing method of putting piles in place for self-elevating platforms is to put piles in place according to the placement plan. The risk of slippage is not reasonably judged before the operation, and the degree, size, direction of slippage are not warned in advance, and no corresponding plan for pile slippage is made. As a result, in the actual placement and piling operation, the coverage capacity is greatly reduced, and complex situations such as collision with the platform and damage to the lifting structure occur frequently, which increases the difficulty of placement, reduces the efficiency of placement, causes great safety hazards to the staff and large facilities, and affects the progress of oilfield exploration and development. Summary of the invention

[0004] The problem to be solved by the present invention is to provide a semi-quantitative method for determining slippage in pile driving operations of a jack-up platform, which helps to determine the slippage risk of multiple pile driving operations of the jack-up platform, provide safety warnings for pile driving operations, and formulate plans for pile driving operations, thereby ensuring the safety of pile driving operations on the jack-up platform, minimizing the risk of slippage, ensuring the safety of large-scale facilities and personnel, and promoting the development of offshore oil fields.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a semi-quantitative determination method for slippage of a self-elevating platform pile driving operation, comprising the following steps:

[0006] S1: Investigate the morphology of old pile pits;

[0007] S2: analyzing the survey parameters of the old pile pit;

[0008] S3: Design the jack-up platform positioning plan and determine the jack-up platform location;

[0009] S4: determining the overlap ratio between the pile shoe and the old pile pit area;

[0010] S5: Analyze the slope and collapse backfill of the old pile pit;

[0011] S6: Analyze the distance between pile centers;

[0012] S7: Determine a comparison value between the diameter of the pile shoe of the self-elevating platform for pile insertion in this situ and the diameter of the pile shoe of the old pile pit, and a comparison value between the predicted depth of the pile insertion in this situ and the depth of the old pile pit;

[0013] S8: Analyze the deadweight and fully loaded ballast of the jack-up platform;

[0014] S9: Analyze the overall sliding trend of the three piles;

[0015] S10: Form a table of pile slippage influencing factors and slippage risk levels;

[0016] S11: Obtaining a semi-quantitative determination result of slip.

[0017] Further, the S1 comprises the following steps:

[0018] S11: Determine the production platform placement area as a preliminary survey range, wherein the size of the preliminary survey range is a square area of ​​200m×200m;

[0019] S12: The depth of the old pile pit is measured by multi-beam, the cross-section through the center of the old pile pit is measured by shallow profiling, the diameter and slope angle of the old pile pit after the piles are pulled out are obtained, and the seabed topography and the undulating shape of the old pile pit are obtained by side-scan sonar.

[0020] Further, the S2 comprises the following steps:

[0021] S21: analyzing the old pile pit depth data, wherein the old pile pit depth data is a comparison between the predicted pile insertion depth of the old pile pit and the actual depth of the survey;

[0022] S22: analyzing the old pile pit diameter data, wherein the old pile pit diameter data is an analysis of the actual pile pit diameter after the pile is pulled out and the geometric diameter Do of the pile shoe of the old pile pit, so as to determine the collapse backfill situation when the pile is pulled out;

[0023] S23: Analyze the slope surface data, wherein the slope surface data is obtained through a shallow profile to obtain an inclination angle of the slope surface.

[0024] Further, the S3 comprises the following steps:

[0025] S31: Design and select the jack-up platform and pile shoe diameter Dn for the emplacement scheme;

[0026] S32: The placement plan designs the bow direction, longitudinal distance and lateral deviation of the ship to determine the position of the pile shoe of the self-elevating platform for pile insertion.

[0027] Further, the S4 comprises the following steps:

[0028] S41: Determine the area overlap ratio, that is, the percentage of the overlap area between the pile shoe area and the old pile pit area in the emplacement plan to the pile shoe area;

[0029] S42: determining the comprehensive area overlap ratio, that is, the percentage of the sum of the overlap ratios of each pile leg and the old pile pit to the number of pile legs;

[0030] S43: The area overlap ratio is divided into 4 levels: the low slip risk level is that the overlap area accounts for 0% to 20% and 96% to 100% of the pile shoe area; the medium slip risk level is 21% to 40%; the medium-high slip risk level is 41% to 60%; and the high slip risk level is 61% to 95%.

[0031] Further, the S5 comprises the following steps:

[0032] S51: Analyze the slope of the old pile pit. The slope is the angle between the slope surface and the horizontal line, and the angle range is 0° to 90°;

[0033] S52: The slope is divided into 4 levels: low slip risk level slope is 0°~20°; medium slip risk level is 21°~50°; medium-high slip risk level is 51°~70°; high slip risk level is 71°~90°;

[0034] S53: Analyze collapse backfill. Collapse backfill refers to the amount of soil that falls into the pile pit due to the collapse of the pile pit wall when the pile is pulled out. The backfill amount is calculated according to the ratio of the difference between the actual pile insertion depth and the pre-survey depth after pile extraction to the actual pile insertion depth.

[0035] S54: The percentage of collapse backfill volume to the pile shoe pit volume is divided into 4 levels: the low slip risk level is that the collapse backfill volume accounts for 80% to 100% of the pile shoe pit volume; the medium slip risk level is 70% to 80%; the medium-high slip risk level is 30% to 50%; and the high slip risk level is 0% to 30%.

[0036] Further, the S6 comprises the following steps:

[0037] S61: After connecting the center of the pile shoe of the current pile insertion with the center of the old pile pit, the length of the connecting line is measured, and the distance between the pile centers is obtained by dividing the length of the connecting line by Dn+Do;

[0038] S62: The pile center distance L is divided into four levels: the low slip risk level pile center distance is ≥1 / 2 (Dn+Do); the medium slip risk level is 1 / 4 (Dn+Do)~1 / 2 (Dn+Do); the medium-high slip risk level is 0~1 / 4 (Dn+Do); and the high slip risk level is 1 / 4 (Dn+Do).

[0039] Further, the S7 comprises the following steps:

[0040] S71: Measure the ratio D1 of the diameter Dn of the pile shoe of the self-elevating platform for pile insertion and the diameter Do of the pile shoe of the old pile pit;

[0041] S72: measuring the ratio d1 of the predicted pile insertion depth Sn to the old pile pit depth So;

[0042] S73: D1 is divided into four levels: low slip risk level is D1 ≥ 1.5; medium slip risk level is 1 ≤ D1 < 1.5; medium-high slip risk level is 0.5 ≤ D1 < 1; high slip risk level is D1 < 0.5;

[0043] S74: d1 is divided into 4 levels: low slip risk level is d1≥1, d1≤0.5; medium slip risk level is 0.5<d1≤0.7; medium-high slip risk level is 0.7<d1≤0.8; high slip risk level is 0.8<d1<1.

[0044] Further, the S9 comprises the following steps:

[0045] S91: connect the centers of the three pile shoes of the self-elevating platform for pile insertion to form a triangle T1;

[0046] S92: connect the centers of the old pile shoe pits to form a triangle T2;

[0047] S93: Compare the shapes and misalignment between T1 and T2, and divide the overall slip trends of the three piles into four levels.

[0048] Further, the S11 includes the following steps:

[0049] S111: The risk level of each influencing factor is comprehensively judged, among which the influencing factors of pile slippage are pile shoe overlap area, pile pit slope, collapse backfill, pile center distance, insertion depth ratio and diameter ratio, deadweight and full load ballast from high to low;

[0050] S112: According to the actual weights of the influencing factors, the levels are selected and the final judgment results are obtained, wherein the weights of the influencing factors for slip judgment are from high to low as follows: overall slip of three piles > area overlap ratio > slope > collapse backfill > new and old insertion depth ratio > pile center distance > pile shoe diameter ratio > deadweight and full load ballast.

[0051] The advantages and positive effects of the present invention are:

[0052] The present invention integrates the influencing factors of the slippage risk of the pile driving operation of the jack-up platform, and the slippage risk judgment is more comprehensive; the influence degree of the influencing factors is quantified to form a quantitative basis for the influencing factors; a more accurate prediction and judgment basis for the overall slippage risk of the jack-up platform is provided, the safety of large-scale offshore facility operations and personnel is ensured, and the development process of offshore oil fields is promoted. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is an overall process flow chart of an embodiment of the present invention.

[0054] Figure 2 Schematic diagram of a preliminary investigation area according to an embodiment of the present invention.

[0055] Figure 3 It is a schematic diagram of preliminary investigation results of an embodiment of the present invention.

[0056] Figure 4 It is a schematic diagram of the positioning scheme and platform position of an embodiment of the present invention.

[0057] Figure 5 It is a schematic diagram of the pile center distance calculation principle of an embodiment of the present invention.

[0058] Figure 6 3 is an overall sliding trend analysis diagram of three piles according to an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0061] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0062] The embodiments of the present invention are further described below in conjunction with the accompanying drawings:

[0063] like Figure 1 As shown, a semi-quantitative method for determining slippage of a self-elevating platform pile driving operation comprises the following steps:

[0064] S1: Investigate the morphology of the old pile pit. Specifically, first determine the scope of the preliminary investigation. The scope of the preliminary investigation is the area where the production platform is in place. The preliminary investigation scope selected in this embodiment is a square area of ​​200m×200m. The preliminary investigation work includes three parts: multi-beam sounding, shallow stratum profile, and side-scan sonar. Through the above operations, the preliminary investigation can obtain the depth, diameter, slope surface (slope) and other parameters of the old pile pit. Specifically, in this embodiment, the depth of the old pile pit is measured by multi-beam, the cross-center profile of the old pile pit is measured by shallow profiling, the diameter and slope angle of the old pile pit after pile extraction are obtained, and the seabed topography and the undulating shape of the old pile pit are obtained by side-scan sonar.

[0065] S2: Analyze the survey parameters of the old pile pit. Specifically, the survey parameters include the old pile pit depth data, diameter data, and slope surface parameters. The old pile pit depth data analysis is to compare the predicted pile insertion depth of the old pile pit with the actual depth of the survey. The depth difference between the predicted pile insertion depth of the old pile pit and the actual depth of the survey can be used as an auxiliary basis for qualitative analysis of the backfill percentage; the old pile pit diameter data analysis is to analyze the actual pile pit diameter after pile extraction and the geometric diameter Do of the old pile pit pile shoe to determine the collapse backfill situation when the pile is extracted; the slope surface data analysis mainly obtains the inclination angle of the slope surface through shallow profiles.

[0066] S3: Design the jack-up platform placement plan and determine the jack-up platform location. Specifically, the jack-up platform and pile shoe diameter Dn are determined by the jack-up platform design and selection; the jack-up platform placement plan designs the bow direction, longitudinal distance and lateral deviation to determine the location of the pile shoe of the jack-up platform for this pile insertion. Among them, the jack-up platform placement plan includes the pile shoe, the shape of the old pile pit, and the pile insertion depth and the old pile pit depth. The depth is expressed in numbers in meters.

[0067] S4: Determine the overlap ratio between the pile shoe and the old pile pit. Specifically, the percentage of the overlap area between the pile shoe area and the old pile pit area in the placement plan to the pile shoe area is the area overlap ratio, in %; comprehensive area overlap ratio = the sum of the overlap ratios of each pile leg and the old pile pit / the number of pile legs; preferably, the area overlap ratio is divided into 4 levels, the low slip risk level is 0% to 20% and 96% to 100% of the overlap area of ​​the pile shoe; the medium slip risk level is 21% to 40%; the medium-high slip risk level is 41% to 60%; the high slip risk level is 61% to 95%.

[0068] S5: Analyze the slope and collapse backfill of the old pile pit. Specifically, the slope is the angle between the slope surface and the horizontal line, and the angle range is 0°~90°. Preferably, the slope is divided into 4 levels, with a low slip risk level slope of 0°~20°; a medium slip risk level of 21°~50°; a medium-high slip risk level of 51°~70°; and a high slip risk level of 71°~90°. Collapse backfill refers to the amount of soil that falls into the pile pit due to the collapse of the pile pit wall when the pile is pulled out. The backfill amount is generally calculated according to the ratio of the difference between the actual pile insertion depth and the pre-survey depth after pile extraction to the actual pile insertion depth. Preferably, the percentage of collapse backfill volume to the pile shoe pit volume is divided into four levels: low slip risk level is that the collapse backfill volume accounts for 80% to 100% of the pile shoe pit volume; medium slip risk level is 70% to 80%; medium-high slip risk level is 30% to 50%; and high slip risk level is 0% to 30%.

[0069] S6: Analyze the pile center distance. Specifically, after connecting the center of the pile shoe of the current pile with the center of the old pile pit, measure the length of the connection line, and divide the length of the connection line by Dn+Do to calculate the pile center distance. Preferably, the pile center distance L is divided into four levels: the pile center distance of the low slip risk level is ≥1 / 2(Dn+Do); the medium slip risk level is 1 / 4(Dn+Do)~1 / 2(Dn+Do); the medium-high slip risk level is 0~1 / 4(Dn+Do); and the high slip risk level is 1 / 4(Dn+Do).

[0070] S7: Determine the comparison value between the diameter of the pile shoe of the self-elevating platform for pile insertion and the diameter of the pile shoe of the old pile pit, and the comparison value between the predicted depth of the pile insertion and the depth of the old pile pit. Specifically, the ratio of the diameter of the pile shoe Dn of the self-elevating platform for pile insertion and the diameter of the pile shoe of the old pile pit Do is D1; ​​the ratio of the predicted depth of pile insertion Sn and the depth of the old pile pit So is d1. Preferably, D1 is divided into four levels, the low slip risk level is D1≥1.5; the medium slip risk level is 1≤D1<1.5; the medium-high slip risk level is 0.5≤D1<1; and the high slip risk level is D1<0.5. d1 is divided into 4 levels, the low slip risk level is d1≥1, d1≤0.5; the medium slip risk level is 0.5<d1≤0.7; the medium-high slip risk level is 0.7<d1≤0.8; and the high slip risk level is 0.8<d1<1.

[0071] S8: Analyze the deadweight and full load ballast of the jack-up platform. Specifically, the load generated by the jack-up platform from floating to the hull leaving the water is the deadweight ballast, and the slip risk generated by the deadweight ballast is low and medium slip risk. The maximum preload of the jack-up platform is the full load ballast, and the risk generated by the full load ballast is medium-high and high slip risk.

[0072] S9: Analyze the overall sliding trend of the three piles. Specifically, the center lines of the three pile shoes of the self-elevating platform for this pile insertion form a triangle T1; the center lines of the old pile shoe pits form a triangle T2. Preferably, the overall sliding trend of the three piles is divided into 4 levels. The low sliding risk level is that the shapes of T1 and T2 are not much different and the misalignment is small, and the stern pile and bow pile of the self-elevating platform do not have a splitting trend; the medium sliding risk level is that the shapes of T1 and T2 are not much different and the misalignment is moderate, and the stern pile and bow pile of the self-elevating platform have a certain splitting trend; the medium-high sliding risk level is that the shapes of T1 and T2 are greatly different and the misalignment is large, and the bow pile and stern pile of the self-elevating platform have a relatively obvious splitting trend; the high sliding risk level is that the shapes of T1 and T2 are greatly different and the misalignment is large, and the bow pile and stern pile of the self-elevating platform have a very obvious splitting trend. If the sliding direction of the three piles is consistent, overall longitudinal sliding or lateral sliding occurs.

[0073] S10: Form a table of pile slippage influencing factors and slippage risk levels, as shown in Table 1.

[0074] Table 1 Slip influence factors and slip levels

[0075]

[0076]

[0077] The vertical content of the table of factors affecting pile slippage and risk levels of slippage is the factors, which are pile shoe overlap area, pile pit slope, collapse backfill, pile center distance, insertion depth ratio to diameter ratio, deadweight and full load ballast from high to low. The horizontal content of the table of factors affecting pile slippage and risk levels of slippage is the risk level of slippage, which is low, medium, medium-high and high from left to right.

[0078] S11: Obtain the semi-quantitative judgment result of slip. Specifically, the risk level of each influencing factor is comprehensively judged, and the level is selected according to the actual weight of the influencing factor to obtain the final judgment result. Among them, the weights of the influencing factors for slip judgment are from high to low: overall slip of three piles > area overlap ratio > slope > collapse backfill > new and old insertion depth ratio > pile center distance > pile shoe diameter ratio > deadweight and full load ballast. The influencing factors need to be analyzed one by one according to the actual in-situ operation conditions, or two or even three factors need to be comprehensively analyzed. When the old pile pit parameters including the old pile pit diameter, position, depth, etc. are missing, the old pile pit morphology of the preliminary investigation results is used as a judgment factor. The four influencing factors of collapse backfill, new and old insertion depth ratio, pile center distance, and pile shoe diameter ratio are no longer used as judgment factors.

[0079] It is worth noting that the semi-quantitative determination result of slip in this embodiment is the result of comprehensive analysis and determination based on the conditions and parameters of the new and old pile pits in the jack-up platform placement plan and the slip risk level table. The semi-quantitative determination result is not equivalent to quantitative prediction and can only be used as a reference for the trend and risk of pile slip.

[0080] The present invention is described in detail below by taking the example of a self-elevating platform A inserting piles into a production platform B. It is known that the diameter of the pile shoe of the drilling platform A is Dn=16, and the predicted insertion depth Sn=6.5 meters. Specifically, the following steps are included:

[0081] S1: Investigate the morphology of the old pile pit. Figure 2 As shown in the figure, the pre-survey scope is determined, with the front of the notch area of ​​the B production platform and the side of the jack-up platform in position as the pre-survey scope. The pre-survey scope is determined as the square area of ​​200 meters × 200 meters enclosed by the intersection of the center line of the notch area of ​​the B production platform and the edge of the platform on the in-position side, 100 meters to the left and right, and 200 meters in the longitudinal direction.

[0082] The offshore oil engineering survey vessel was used to complete the survey operations of multi-beam bathymetry, shallow stratum profile, side-scan sonar, etc. Among them, the depth of the old pile pit was measured by multi-beam, the cross-center profile of the old pile pit was measured by shallow profile, the diameter and slope angle of the old pile pit after the pile was pulled out were obtained, and the seabed topography and the undulating shape of the old pile pit were obtained by side-scan sonar.

[0083] S2: Analyze the survey parameters of the old pile pit. Figure 3As shown, the depth, diameter, slope (slope) and other parameters of the old pile pit can be obtained through preliminary investigation. Among them, the old pile pit has a depth of 3.3m / 3.6m / 3.5m, a diameter of 12m, and a slope of 42°.

[0084] Analysis of the old pile pit depth data: The predicted pile insertion depth of the old pile pit was 4.6 meters. After comparing and analyzing the actual depth of the survey, the old pile pit was backfilled by about 1 meter.

[0085] Analysis of the old pile pit diameter data: the actual pile pit diameter after pile extraction is 12 meters and the geometric diameter of the old pile pit pile shoe is Do=10 meters.

[0086] After comparing the depth and diameter, the collapse backfill ratio is approximately 20%, which is less than 30%, and the collapse backfill grade is high.

[0087] S3: Design a plan for the placement of the jack-up platform and determine the location of the jack-up platform. Figure 4 As shown in the figure, the jack-up platform A and the diameter of the A pile shoe Dn = 16 meters are selected in the design of the emplacement scheme. The bow direction, longitudinal distance and lateral deviation of the emplacement scheme design determine the position of the pile shoe of the jack-up platform for this pile insertion. The bow direction of the A platform is 99°, the longitudinal distance and deviation are 9.6-10.2 meters, and the lateral deviation is ±0.3 meters.

[0088] Among them, the placement plan includes that the pile shoe of drilling platform A is circular, the old pile pit is a central circle with three sickles, the depth of the pile pit, the shape of the old pile pit, as well as the depth of the pile insertion and the depth of the old pile pit are 3.3 meters / 3.6 meters / 3.5 meters.

[0089] S4: Determine the overlap ratio between the pile shoe and the old pile pit. The overlap ratio is the percentage of the overlap area between the pile shoe area of ​​the jack-up platform A and the old pile pit area in the placement plan to the area of ​​the pile shoe A. The overlap area between the 1# pile and the 1# old pile pit accounts for 5% of the 1# pile shoe area, the overlap area between the 2# pile and the 2# old pile pit accounts for 20% of the 2# pile shoe area, and the overlap area between the 3# pile and the 3# old pile pit accounts for 50% of the 3# pile shoe area.

[0090] The comprehensive area overlap ratio is (5%+20%+50%) / 3=25%.

[0091] The levels are divided according to the area overlap ratio, 25% is between 21% and 40%, which belongs to the medium slip risk level.

[0092] S5: Analyze the slope of the old pile pit and the collapse backfill. Among them, through preliminary investigation, the slope of the old pile pit is 42°. The slope of the old pile pit is divided into grades, and 42° is between 21° and 50°, which belongs to the medium sliding wind.

[0093] After the jack-up platform A is in place, the actual pile insertion depth is 4.5 / 4.6 / 4.5 meters. The pre-surveyed old pile pit depth, that is, the pile pit depth after the pile is pulled out, is 3.3 meters / 3.6 meters / 3.5 meters. The backfill percentage of the 1# old pile pit = (4.5-3.3) / 4.5×100% = 26.6%, the backfill percentage of the 2# old pile pit = (4.6-3.6) / 4.6×100% = 21.7%, and the backfill percentage of the 3# old pile pit = (4.5-3.5) / 4.5×100% = 22.2%; the comprehensive backfill ratio of the three old pile pits is (26.6%+21.7%+22.2%) / 3 = 23.5%. The level is divided according to the percentage of the collapsed backfill volume to the pile shoe pit volume, which is between 0% and 30%, belonging to the high slip risk level.

[0094] S6: Analyze the distance between the pile center, that is, the geometric relationship between the pile shoe and the center of the old pile pit. Figure 5 As shown, according to S2, Dn=16 meters, Do=10 meters, Dn+Do=26 meters, the lengths of the line connecting the center of the pile shoe of the jack-up platform A and the center of the old pile pit are 1#: 11.8 meters, the center distance of 1# pile is 11.8 / 26=0.45, 2#: 9.9 meters, the center distance of 2# pile is 9.9 / 26=0.38, 3#: 7.5 meters, the center distance of 3# pile is 7.5 / 26=0.29, and the comprehensive center distance is 0.37 (Dn+Do), which is between 1 / 4 (Dn+Do) and 1 / 2 (Dn+Do), belonging to the medium slip risk level.

[0095] S7: Comparison of the diameter and predicted depth of the pile shoe of the self-elevating platform for pile insertion with the old pile pit (diameter ratio, depth ratio). Among them, the diameter of the pile shoe of the self-elevating platform for pile insertion Dn / the diameter of the pile shoe of the old pile pit Do=16 / 10=1.6=D1. According to the classification of D1, 1.6>1.5, which belongs to the low slip risk level.

[0096] The ratio of the predicted depth Sn of this pile insertion to the old pile pit depth So is d1=6.5 / 4.5=1.44; according to the classification based on d1, 1.44>1, which belongs to the low slip risk level.

[0097] S8: Analyze the deadweight and full ballast of the jack-up platform. Specifically, the jack-up platform needs to reach full load, so the risk of slippage is medium to high.

[0098] S9: Analyze the overall sliding trend of the three piles. Specifically, Figure 6 As shown, the connecting lines of the three pile shoes of the jack-up platform A form a triangle T1; the connecting lines of the centers of the old pile shoe pits form a triangle T2; by observing the two triangles T1 and T2, the shapes of piles T1 and T2 are not much different and the misalignment is moderate, and the two stern piles and bow piles have a certain splitting tendency; it belongs to the medium slip risk.

[0099] S10: Form a table of pile slippage influencing factors and slippage risk levels, as shown in Table 2.

[0100] Table 2 A Self-elevating platform pile insertion B Production platform slippage semi-quantitative determination table

[0101] Slip risk Low middle Medium to high high Area overlap ratio √ Slope √ Collapse backfill √ Ratio of new and old insertion depth √ Pile center distance √ Shoe diameter ratio √ Deadweight and ballast load √ Three pile sliding √ Semi-quantitative determination results √

[0102] S11: Obtaining a semi-quantitative determination result of slip;

[0103] According to the level and weight of each sub-item slippage risk, it is finally determined that the slippage risk of the jack-up platform A during the piling operation on the B platform is medium.

[0104] The advantages and positive effects of the present invention are:

[0105] The present invention integrates the influencing factors of the slippage risk of the pile driving operation of the jack-up platform, and the slippage risk judgment is more comprehensive; the influence degree of the influencing factors is quantified to form a quantitative basis for the influencing factors; a more accurate prediction and judgment basis for the overall slippage risk of the jack-up platform is provided, the safety of large-scale offshore facility operations and personnel is ensured, and the development process of offshore oil fields is promoted.

[0106] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A semi-quantitative method for determining slippage during pile driving operation of a self-elevating platform, characterized in that: The following steps are included: S1: Investigate the morphology of old pile pits; S2: analyzing the survey parameters of the old pile pit; S3: Design the jack-up platform positioning plan and determine the jack-up platform location; S4: determining the overlap ratio between the pile shoe and the old pile pit area; S5: Analyze the slope and collapse backfill of the old pile pit; S6: Analyze the distance between pile centers; S7: Determine a comparison value between the diameter of the pile shoe of the self-elevating platform for pile insertion in this situ and the diameter of the pile shoe of the old pile pit, and a comparison value between the predicted depth of the pile insertion in this situ and the depth of the old pile pit; S8: Analyze the deadweight and fully loaded ballast of the jack-up platform; S9: Analyze the overall sliding trend of the three piles; S10: Form a table of pile slippage influencing factors and slippage risk levels; S11: Obtaining a semi-quantitative determination result of slip.

2. A semi-quantitative determination method for slippage in pile driving operation of a self-elevating platform according to claim 1, characterized in that: The S1 comprises the following steps, S11: Determine the production platform placement area as a preliminary survey range, wherein the size of the preliminary survey range is a square area of ​​200m×200m; S12: The depth of the old pile pit is measured by multi-beam, the cross-section through the center of the old pile pit is measured by shallow profiling, the diameter and slope angle of the old pile pit after the piles are pulled out are obtained, and the seabed topography and the undulating shape of the old pile pit are obtained by side-scan sonar.

3. A semi-quantitative determination method for slippage in pile driving operation of a self-elevating platform according to claim 1 or 2, characterized in that: The S2 comprises the following steps, S21: analyzing the old pile pit depth data, wherein the old pile pit depth data is a comparison between the predicted pile insertion depth of the old pile pit and the actual depth of the survey; S22: analyzing the old pile pit diameter data, wherein the old pile pit diameter data is an analysis of the actual pile pit diameter after the pile is pulled out and the geometric diameter Do of the pile shoe of the old pile pit, so as to determine the collapse backfill situation when the pile is pulled out; S23: Analyze the slope surface data, wherein the slope surface data is obtained through a shallow profile to obtain an inclination angle of the slope surface.

4. A semi-quantitative determination method for slippage in pile driving operation of a self-elevating platform according to claim 1 or 2, characterized in that: The S3 comprises the following steps, S31: Design and select the jack-up platform and pile shoe diameter Dn for the emplacement scheme; S32: The placement plan designs the bow direction, longitudinal distance and lateral deviation of the ship to determine the position of the pile shoe of the self-elevating platform for pile insertion.

5. A semi-quantitative determination method for slippage in pile driving operation of a self-elevating platform according to claim 1 or 2, characterized in that: The S4 comprises the following steps, S41: Determine the area overlap ratio, that is, the percentage of the overlap area between the pile shoe area and the old pile pit area in the emplacement plan to the pile shoe area; S42: determining the comprehensive area overlap ratio, that is, the percentage of the sum of the overlap ratios of each pile leg and the old pile pit to the number of pile legs; S43: The area overlap ratio is divided into 4 levels: low slip risk level is when the overlap area accounts for 0% to 20% and 96% to 100% of the pile shoe area; medium slip risk level is 21% to 40%; medium-high slip risk level is 41% to 60%; The high slip risk level is 61% to 95%.

6. A semi-quantitative determination method for slippage in pile driving operation of a self-elevating platform according to claim 1 or 2, characterized in that: The S5 comprises the following steps: S51: Analyze the slope of the old pile pit. The slope is the angle between the slope surface and the horizontal line, and the angle range is 0° to 90°; S52: The slope is divided into 4 levels: low slip risk level slope is 0°~20°; medium slip risk level is 21°~50°; medium-high slip risk level is 51°~70°; high slip risk level is 71°~90°; S53: Analyze collapse backfill. Collapse backfill refers to the amount of soil that falls into the pile pit due to the collapse of the pile pit wall when the pile is pulled out. The backfill amount is calculated according to the ratio of the difference between the actual pile insertion depth and the pre-survey depth after pile extraction to the actual pile insertion depth. S54: The percentage of the amount of collapse backfill to the volume of the pile shoe pit is divided into 4 levels: the low slip risk level is 80% to 100% of the volume of the pile shoe pit; the medium slip risk level is 70% to 80%; the medium-high slip risk level is 30% to 50%; The high slip risk level is 0% to 30%.

7. A semi-quantitative determination method for slippage in pile driving operation of a self-elevating platform according to claim 1 or 2, characterized in that: The S6 comprises the following steps, S61: After connecting the center of the pile shoe of the current pile insertion with the center of the old pile pit, the length of the connecting line is measured, and the pile center distance is calculated by dividing the connecting line length by Dn+Do; S62: The pile center distance L is divided into four levels: the pile center distance of the low slip risk level is ≥1 / 2 (Dn+Do); the medium slip risk level is 1 / 4 (Dn+Do) to 1 / 2 (Dn+Do); the medium-high slip risk level is 0 to 1 / 4 (Dn+Do); The high slip risk level is 1 / 4 (Dn+Do).

8. A semi-quantitative determination method for slippage in pile driving operation of a self-elevating platform according to claim 1 or 2, characterized in that: The S7 comprises the following steps, S71: Measure the ratio D1 of the diameter Dn of the pile shoe of the self-elevating platform for pile insertion and the diameter Do of the pile shoe of the old pile pit; S72: measuring the ratio d1 of the predicted pile insertion depth Sn to the old pile pit depth So; S73: D1 is divided into four levels: low slip risk level is D1 ≥ 1.5; medium slip risk level is 1 ≤ D1 < 1.5; medium-high slip risk level is 0.5 ≤ D1 < 1; The high slip risk level is D1 < 0.5; S74: d1 is divided into 4 levels: low slip risk level is d1≥1, d1≤0.5; medium slip risk level is 0.5<d1≤0.7; medium-high slip risk level is 0.7<d1≤0.8; high slip risk level is 0.8<d1<1.

9. A semi-quantitative determination method for slippage in pile driving operation of a self-elevating platform according to claim 1 or 2, characterized in that: The S9 comprises the following steps, S91: connect the centers of the three pile shoes of the self-elevating platform for pile insertion to form a triangle T1; S92: connect the centers of the old pile shoe pits to form a triangle T2; S93: Compare the shapes and misalignment between T1 and T2, and divide the overall slip trends of the three piles into four levels.

10. A semi-quantitative determination method for slippage in pile driving operation of a self-elevating platform according to claim 1 or 2, characterized in that: The S11 comprises the following steps: S111: The risk level of each influencing factor is comprehensively judged, among which the influencing factors of pile slippage are pile shoe overlap area, pile pit slope, collapse backfill, pile center distance, insertion depth ratio and diameter ratio, deadweight and full load ballast from high to low; S112: According to the actual weights of the influencing factors, the levels are selected and the final judgment results are obtained, wherein the weights of the influencing factors for slip judgment are from high to low as follows: overall slip of three piles > area overlap ratio > slope > collapse backfill > new and old insertion depth ratio > pile center distance > pile shoe diameter ratio > deadweight and full load ballast.

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