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Floating platform and method of floating state keeping and stability control during loading and unloading process

09834287 · 2017-12-05

Assignee

Inventors

Cpc classification

International classification

Abstract

The present invention discloses a floating platform, wherein multiple layers of compartments are configured along the height direction of the floating platform, and the center of gravity of each layer of compartments in a full-load process and a loading and unloading process is always located on a vertical line where the whole center of gravity of the floating platform is located; the multiple annular compartments are of equal-ratio subdivision in volume: the volume ratio of every two adjacent upper and lower annular compartments is inversely proportional to the density of liquid stored in the compartments; in the practical loading process, the floating platform is always kept at a constant displacement to maintain the waterplane unchanged by adjusting crude oil or seawater loaded in different layers of compartments, and thus the floating plate always has optimal hydrodynamic performance.

Claims

1. A floating platform, comprising: a first annular layer, a last annular layer, and one or more intermediary annular layers arranged in a vertical direction between the first annular layer and the last annular layer, each of the annular layers comprises a plurality of compartments, wherein a center of gravity of each of the annular layers and a center of gravity of the floating platform are located on a vertical line, wherein a volume ratio between two adjacent annular layers satisfies
V.sub.B/V.sub.A=ρ.sub.water/ρ.sub.oil, wherein the two adjacent annular layers are any of two annular layers adjacent immediately to each other selected from the group consisting of the first annular layer, the last annular layer, and the one or more intermediary annular layers, and wherein V.sub.A is a total volume of a lower annular layer among the two adjacent annular layers, V.sub.B is a total volume of an upper annular layer among the two adjacent annular layers, ρ.sub.water is a density of seawater, and ρ.sub.oil is a density of a crude oil.

2. The floating platform according to claim 1, wherein the plurality of compartments in each of the annular layers are fluidly connected.

3. The floating platform according to claim 1, wherein each of the annular layers has a same inner diameter.

4. The floating platform according to claim 3, wherein each of the annular layers comprises a plurality of transverse bulkheads.

5. The floating platform according to claim 1, wherein the floating platform comprises a double-layer hull and a double-layer bottom, wherein the double-layer bottom comprises one or more annular load regulating compartments, and wherein the first annular layer is disposed immediately above the double-layer bottom.

6. The floating platform according to claim 5, wherein the double-layer bottom comprises an annular load regulating compartment I and an annular regulating compartment II, wherein a center of gravity of the annular load regulating compartment I and a center of gravity of the annular regulating compartment II coincide with each other, wherein a ratio of a sum of a volume of the annular load regulating compartment I and a volume of the annular load regulating compartment II and a total volume of the layer of compartments disposed above the double-layer bottom is equal to a ratio of a density of seawater and a density of crude oil.

7. A method of operating the floating platform of claim 5, comprising: filling the one or more of the annular load regulating compartments with seawater; emptying crude oil from the first annular layer; filling the empty first annular layer with seawater; emptying crude oil from and then filling seawater in each of the one or more intermediate annular layers; and emptying crude oil from the last annular layer so that the last annular layer is empty.

8. The method of claim 7, further comprising: filling the empty last annular layer with crude oil; emptying seawater from and then filling crude oil in each of the one or more intermediary annular layers; emptying seawater from and then filling crude oil in the first annular layer; and emptying seawater from the one or more annular load regulating compartments.

9. The floating platform according to claim 5, wherein a ratio of a total volume of the one or more load regulating compartments to a total volume of the first annular layer is inversely proportional to a ratio of the density of seawater and the density of crude oil.

10. The method of claim 7, wherein each of the one or more intermediate layers in an upward direction are sequentially subject to the steps of emptying crude oil and filling seawater.

11. The floating platform according to claim 8, wherein each of the one or more intermediate layers in a downward direction are sequentially subject to the steps of emptying seawater and filling crude oil.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Accompanying drawings that need to be used in description of the embodiments or the existing technology will be briefly introduced below in order to illustrate the embodiments of the present invention and the technical solution of the existing technology, and it is apparent for those common skilled in the art that the accompany drawings described as below are just some embodiments of the present invention and other accompany drawings can be acquired on the basis of those accompany drawings on the premise of not paying creative work.

(2) FIGS. 1 to 14 are schematic diagrams of the embodiment of the present invention in the loading and unloading process;

(3) FIG. 15 is an effect schematic diagram of the embodiment of the present invention; and

(4) In drawings, A, B, C, D, E and F are compartments of the platform, which are distributed vertically and configured in six layers; ‘+’ and ‘−’ above each drawing represent loading and unloading for the compartment, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) The technical solution in the embodiments of the present invention is described clearly and completely in conjunction with the accompanying drawings in the embodiments of the present invention in order to make the objective, the technical solution and the advantages of the present invention clearer:

(6) As shown in FIG. 1, the floating platform comprises the double-layer hull and the double-layer bottom, and the section of the floating platform is shaped as a sand clock, wherein the waterplane stands for the narrowest part of the sand clock. Six annular compartments, namely the annular compartment IA, the compartment IIB, the compartment IIIC, the compartment IVD, the compartment VE and the compartment VIF are sequentially configured from bottom to top. The six compartments are of equal-ratio subdivision, namely

(7) V B V A = V C V B = V D V C = V E V D = V F V E = ρ water ρ oil ,

(8) wherein, V.sub.A, V.sub.B, V.sub.C, V.sub.D, V.sub.E and V.sub.F are volumes of the annular compartment IA, the compartment IIB, the compartment IIIC, the compartment IVD, the compartment VE and the compartment VIF, respectively.

Embodiment I

Loading and Unloading Process

(9) In order to ensure that the vertical position of the buoyant center and define the vertical change of the center of gravity to be always positioned in a safe and controllable range, the present invention formulates a set of novel loading and unloading process in combination with said subdivision design.

(10) If the platform has a drilling function unit, two working conditions, namely a drilling working procedure and an oil production working procedure are generally mentioned. Under the drilling working procedure, the floating state is regulated by adopting ballast water as well to ensure that the waterplane of the platform is always kept at a full-load waterplane position. This process is clear and thus free of special illustration here. The loading and unloading process under the oil production working procedure will be illustrated in two stages to make it easy to understand:

(11) at the first stage of the production working procedure: full-load of crude oil and start of raw oil output are as shown in FIGS. 1-7.

(12) Under the full-load working processes, all oil storage compartments A, B, C, D, E and F are filled with oil and the load regulating compartments are in an unloaded state.

(13) And the steps are performed as follows:

(14) Step 1: evacuating all oil in the compartment A by pumping, wherein the two load regulating compartments BAL1 and BAL2 must be filled with water so as to ensure that the total mass of the platform is unchanged;

(15) Step 2: evacuating all oil in the compartment B by pumping and fully filling the compartment A with water, wherein the volume of water in the load adjusting compartments is not changed since the mass of evacuated oil is equal to that of added water;

(16) Step 3: adopting the same theory as Step 2, directly evacuating all oil in the compartment C by pumping and fully filling the compartment B with water;

(17) Step 4: evacuating all oil in the compartment D by pumping and fully filling the compartment C with water;

(18) Step 5: evacuating all oil in the compartment E by pumping and fully filling the compartment D with water; and

(19) Step 6: evacuating all oil in the compartment F by pumping and fully filling the compartment E with water, wherein all oil in BAL2 must be correspondingly evacuated since the volume of the compartment E is relatively larger than that of the compartment F and the mass of added water is larger than that of evacuated oil.

(20) When oil in the compartment F is evacuated by pumping, the oil unloading process is ended, and the compartment F is not filled with water and is thus at an empty state for preparations of oil storage of next stage. As known from analysis on weight distribution change of the first stage, during which the whole center of gravity continuously descends, and the whole stability of the platform is continuously improved on the premise that the position of center of buoyance is unchanged.

(21) At the second stage of the production working procedure: full-load of ballast water and start of crude oil input are as shown in FIGS. 8-14.

(22) Under the full-load working conditions, all oil storage compartments A, B, C, D and E are filled with water, the compartment F is empty, the load regulating compartment BAL1 is filled with water and the load regulating compartment BAL2 is in an empty state.

(23) And the following steps are performed as follows:

(24) Step 1: fully filling the compartment F with oil, and simultaneously evacuating all water in the compartment E by pumping, wherein the compartment BAL2 must be fully filled with water to ensure that the floating state of the platform is maintained unchanged since the mass of water in the compartment E is larger than that of oil in the compartment F;

(25) Step 2: fully filling the compartment E with oil and directly evacuating all water in the compartment D by pumping;

(26) Step 3: fully filling the compartment D with oil and directly evacuating all water in the compartment C by pumping;

(27) Step 4: fully filling the compartment C with oil and directly evacuating all water in the compartment B by pumping;

(28) Step 5: fully filling the compartment B with oil and directly evacuating all water in the compartment A by pumping; and

(29) Step 6: fully filling the compartment A with oil and directly evacuating all water in the compartments BAL1 and BAL2 by pumping.

(30) The platform is converted into a static balance state from a dynamic balance state for preparation of next round of work. As known from analysis on weight distribution change of the second stage, during which the position of whole center of gravity moves up continuously, and the whole stability of the platform is reduced continuously on the premise of unchanged position of center of buoyance, but always within a set variable range.

(31) It is worthy of being illustrated that two treatment processes at the crude oil input stage and the crude oil output stage form a closed circulation, the position of the center of buoyance can be maintained unchanged in the input/output process no matterfrom which point the process is started, and the center of gravity fluctuates in a set range without affecting the whole stability and the hydrodynamic performance of the platform. The stability height change is as shown in FIG. 15.

(32) As stated above, the preferable embodiments abovementioned of the present invention are described, however, the present invention is not limited to these embodiments specifically disclosed, equivalent replacement or change, made by any technical personnel skilled in the art disclosed in the present invention in accordance to the technical solution and inventive concept of the present invention, should fall into the protection scope of the present invention.