CN101339255A - Method for accurately measuring and calculating self-elevating drilling platform well position - Google Patents

Abstract

The invention relates to a method for accurately measuring and calculating a well placement of a self-elevating type drilling platform, comprising the following steps: 1) the equation of the transverse amplitude delta<st>, the period T and the natural frequency of the drilling platform is established; 2) the accurate well placement is calculated: a. the coordinates of the well placement measured by the prior art are assumed as b (x, y); and the set coordinates of the well placement are o (x<0>, y<0>); alpha<w> is the direction angle of a wind direction; b. the transverse amplitude delta<st> of the drilling platform in the definite wind direction is calculated and obtained though the step 1); and the quantity of the delta<st> on an x axis is delta<st>(x)equal to sin(alpha<w>)delta<st>; the quantity on a y axis is delta<st>(y)equal to cos(alpha<w>)delta<st>; c. the accurate coordinates b(x', y') are calculated; wherein, x' equal to x-delta<st>(x), x'equal to y-delta<st>(y). The method provided by the invention is explained and applied to a detailed implementation on different sea areas and has significantly actual guiding meaning in improving the placement accuracy of the self-elevating type drilling platform and determining the accurate location of the mouth of the well.

Description

A kind of method of accurate measuring and calculating self-elevating drilling platform well position

Technical field

The present invention relates to a kind of method of accurate measuring and calculating well location, particularly a kind of method of accurate measuring and calculating self-elevating drilling platform well position.

Background technology

Self-elevating drilling platform is the special engineering boats and ships that the offshore oil operation is mainly used, and it is made up of platform, spud leg and elevating mechanism, and platform can be equipped with rig, other plant equipment and living facilities along the spud leg lifting on the platform deck.When self-elevating drilling platform is in place (as shown in Figure 1), adopt the method for hydraulic pressure or machinery that spud leg 1 is inserted the seabed at sea, platform 2 is raised to the trouble free service height that leaves the sea by elevating mechanism then.Final platform 2 rises to the air gap of design, and the height degree that rises of the distance from bottom seabed mud face of platform 2 is L at this moment ₁, the mud degree of depth of going into that spud leg 1 inserts the seabed is L ₂

Self-elevating drilling platform is subjected to the dynamic disturbance of wind, wave, stream in the marine environment operation, produce motion accordingly.Particularly under the wind carrier strip spare, produce the acting force of horizontal direction for self-elevating drilling platform, thereby make self-elevating drilling platform produce transverse vibration, the accurate measuring and calculating to well location has produced the influence that is difficult to ignore like this.In the operation of tieback under water in drilling well later stage,, cause the well head pipeline to be difficult to aim at owing in the measuring and calculating of well location, have error.Have to cut under water when the carrying out operation pipeline of well head welds new pipeline more again.So just marine engineering is installed and cause very big difficulty, wasted resources such as a large amount of personnel, funds.

The measuring and calculating of pithead position in the past all is with the terrestrial coordinate that measures in the average period coordinate as well location, but produce transverse vibration and have amplitude because self-elevating drilling platform is subjected to effect that wind carries, therefore such results of measuring just has than large deviation with respect to the pithead position of reality.The present invention is exactly the research at the vibration characteristics of drilling platform, has proposed concrete solution.

Summary of the invention

At the problems referred to above, the purpose of this invention is to provide a kind of influence of having considered the amplitude of transverse vibration under the wind carrier strip spare to the well location measuring and calculating, accurately the method for measuring and calculating self-elevating drilling platform well position.

For achieving the above object, the present invention takes following technical scheme: a kind of method of accurate measuring and calculating self-elevating drilling platform well position, and it may further comprise the steps:

1) sets up the lateral amplitude of vibration δ of drilling platform _St, period T and natural frequency f _nEquation

${\mathrm{\&delta;}}_{\mathrm{st}}=\frac{P_H\&CenterDot;l^3}{12\mathrm{nEI}}$

$T=2\mathrm{\&pi;}\sqrt{\frac{w}{\mathrm{gk}}}$

$f_n=\frac{1}{T}=\frac{1}{2\mathrm{\&pi;}}\sqrt{\frac{12\mathrm{nEIg}}{{\mathrm{wl}}^3}}$

In the formula: P _H---drilling platform is lateral stressed

L---rise the height degree

N---spud leg number

E---elastic modulus is got E=2.1 * 106kg/cm to steel ²

I---polar moment of inertia is to circular spud leg

$I=\frac{\mathrm{\&pi;}}{64}({\mathrm{OD}}^4-{\mathrm{ID}}^4)\left[{\mathrm{cm}}^4\right]$

OD---external diameter

ID---internal diameter

W---drilling platform deadweight

G---acceleration of gravity

2) calculate well location accurately

A, suppose that the well location coordinate that prior art records is that (x, y), the well location coordinate of setting is o (x to b ₀, y ₀), α _wDeflection for wind direction; B, try to achieve drilling platform by step 1) and determining the lateral amplitude of vibration δ of wind direction _St, δ then _StComponent on the x axle is: δ _St(x)=sin (α _w) δ _StComponent on the y axle is: δ _St(y)=cos (α _w) δ _StC, calculate accurately well location coordinate b ' (x ', y '), wherein x '=x-δ _St(x), x '=y-δ _St(y); B ' (x ', y ') departs from o (x ₀, y ₀) deflection be ${\mathrm{\&alpha;}}^{\&prime;}=\arctan \frac{x^{\&prime;}-x_0}{y^{\&prime;}-y_0}.$

In the described step 1), P _HComputing method as follows:

$P_H=\frac{\begin{array}{cc}r& v^2\end{array}}{2g}{c}_D{A}_p$

In the formula: r---atmospheric density

V---wind speed

c _D---resistance coefficient

A _p---be the projection of drilling platform bulk area on the wind direction vertical plane.

In the described step 1), three spud leg drilling platform, then n=3.

Described step 2) in, (x y) adopts the average of the terrestrial coordinate that records in average period, then lateral amplitude of vibration δ to b _StShould get half.

The present invention is owing to take above technical scheme, it has the following advantages: 1, the present invention is by the dynamical property analysis to self-elevating drilling platform, draw the formula of transverse vibration amplitude, cycle and the natural frequency of self-elevating drilling platform, for quantitative analysis drilling platform transverse vibration characteristic provides theoretical foundation.2, the present invention deducts the size of amplitude, thereby calculates well location coordinate accurately by the result of calculation to the transverse vibration amplitude in the well location coordinate of prior art measuring and calculating.3, the present invention is illustrated the concrete performance in different waters and use, and for precision in place that improves self-elevating drilling platform and the accurate pithead position of measuring, has very important actual directive significance.

Description of drawings

Fig. 1 is that self-elevating drilling platform of the present invention rises the ship synoptic diagram

Fig. 2 is the stressed synoptic diagram of pile legs of self-elevating drilling platform of the present invention

Fig. 3 is a well location coordinate synoptic diagram of the present invention

Fig. 4 is a wind direction synoptic diagram of the present invention

Embodiment

Below in conjunction with drawings and Examples the present invention is described in detail.

As shown in Figure 1, described in the self-elevating drilling platform later situation such as background in place.By drilling platform is carried out force analysis as can be known, the spud leg after this moment, pitching pile was stood is equivalent to the semi-girder of a lower end build-in.For making things convenient for the research of problem, supposing does not have relative displacement between spud leg and the drilling platform, but along with drilling platform translation together.Hence one can see that, and when the drilling platform transverse vibration, the spud leg lower end is mounted in the seabed, and then must there be interior moment M the upper end on it with the drilling platform translation ₀Exist.

1, obtains drilling platform lateral amplitude of vibration, cycle and frequency

As shown in Figure 2, drilling platform 1 deadweight w, rising the height degree is L ₁It is following as position of fixity support drilling platform that spud leg 2 inserts the mud face, and the number of spud leg 2 is more than or equal to 3.Setting up coordinate system is the x axle along the spud leg axial direction, and horizontal direction is the y axle, and spud leg produces lateral amplitude of vibration y under the effect of transverse force P, the maximum transversal amplitude y of spud leg _MaxJust equal the lateral amplitude of vibration δ of drilling platform _StIf rise height degree L ₁=l can ask drilling platform 1 along the axial transverse vibration period T of y.

1) Flexural Equation of spud leg

As shown in Figure 2, in the moment M of coordinate (x, 0) point _xComputing method be:

M _x＝M _o-P(l-x) (1)

At this moment, the second derivative of the Flexural Equation of spud leg is:

$\frac{d^{2}y}{{\mathrm{dx}}^2}=\frac{M_x}{\mathrm{EI}}---\left(2\right)$

And because

$y^{\&prime;}=\&Integral;\frac{M_x}{\mathrm{EI}}\mathrm{dx}---\left(3\right)$

Then going into formula (3) for formula (1) can get:

$y^{\&prime;}=\&Integral;\frac{M_o-P(l-x)}{\mathrm{EI}}\mathrm{dx}$

$y^{\&prime;}=\frac{1}{\mathrm{EI}}[M_{o}x-\mathrm{Plx}+\frac{1}{2}{\mathrm{Px}}^2]+c---\left(4\right)$

Wherein c is an integration constant, and E is an elastic modulus, and I is a polar moment of inertia, to circular spud leg $I=\frac{\mathrm{\&pi;}}{64}({\mathrm{OD}}^4-{\mathrm{ID}}^4),$ OD is the spud leg external diameter, and ID is the spud leg internal diameter.Known boundaries condition: x=0, y '=0, substitution formula (4) can get c=0.The c=0 inverse iteration is gone into (4) Shi Kede:

$y^{\&prime;}=\frac{1}{\mathrm{EI}}[(M_o-\mathrm{Pl})x+\frac{{\mathrm{Px}}^2}{2}]---\left(5\right)$

The Flexural Equation that is got spud leg by formula (5) integration is:

$y=\&Integral;y^{\&prime;}\mathrm{dx}=\&Integral;\frac{1}{\mathrm{EI}}[(M_o-\mathrm{Pl})x+\frac{{\mathrm{Px}}^2}{2}]\mathrm{dx}$

$y=\frac{1}{\mathrm{EI}}[(M_o-\mathrm{Pl})\frac{x^2}{2}+\frac{{\mathrm{Px}}^3}{6}]+d---\left(6\right)$

Wherein d is an integration constant.With boundary condition x=0, y=0 substitution formula (6) can get d=0.The d=0 inverse iteration is gone into the Flexural Equation that formula (6) can get spud leg:

$y=\frac{1}{2\mathrm{EI}}[(M_o-\mathrm{Pl})x^2+\frac{{\mathrm{Px}}^3}{3}]---\left(7\right)$

∵ has extremum conditions y '=0 when x=l again, and then substitution formula (5) can get interior moment of flexure:

$M_o=\frac{P}{2}l---\left(8\right)$

Going into formula (6) for formula (8) can get:

$y=\frac{1}{2\mathrm{EI}}[(-\frac{\mathrm{Pl}}{2})x^2+\frac{{\mathrm{Px}}^3}{3}]---\left(9\right)$

Obviously, when x=l, the maximum value that y reaches absolute value is:

$y_{\max }=\frac{{\mathrm{Pl}}^3}{12\mathrm{EI}}---\left(10\right)$

2) transverse vibration frequency, the cycle of drilling platform

When drilling platform is subjected to transverse force P _HDo the time spent, establishing the spud leg number is n, then the transverse force that is subjected on every spud leg $P=\frac{P_H}{n}.$ With P substitution formula (10), can get the drilling platform amplitude of spud leg x=l:

${\mathrm{\&delta;}}_{\mathrm{st}}=y_{\max }=\frac{P_H\&CenterDot;l^3}{12\mathrm{nEI}}---\left(11\right)$

Wherein,

$P_H=\frac{\begin{array}{cc}r& v^2\end{array}}{2g}{c}_D{A}_P$

R is an atmospheric density, and v is a wind speed; c _DBe resistance coefficient, A _PBe the projection of wind-engaging hull area on the wind direction vertical plane.The bendind rigidity coefficient of spud leg can equivalence be:

$k=\frac{P}{{\mathrm{\&delta;}}_{\mathrm{st}}}=\frac{12\mathrm{nEI}}{l^3}---\left(12\right)$

Then as can be known, the cycle of drilling platform is:

$T=2\mathrm{\&pi;}\sqrt{\frac{w}{\mathrm{gk}}}---\left(13\right)$

Going into formula (13) for formula (12) can get:

$T=2\mathrm{\&pi;}\sqrt{\frac{{\mathrm{wl}}^3}{12\mathrm{ngEI}}}---\left(14\right)$

Wherein, w is the drilling platform deadweight, and g is an acceleration of gravity.Then the transverse vibration natural frequency of drilling platform is:

$f_n=\frac{1}{T}=\frac{1}{2\mathrm{\&pi;}}\sqrt{\frac{12\mathrm{nEIg}}{{\mathrm{wl}}^3}}---\left(15\right)$

3) three spud leg drilling platform transverse vibration amplitudes, cycle and frequency

The present invention considers that many drilling platform are arranged is three spud leg forms, n=3 so at this moment, and the power that then is subjected to horizontal direction on every spud leg is $P=\frac{P_H}{3}.$ With its substitution formula (11), the maximum horizontal displacement that in like manner can get drilling platform is:

${\mathrm{\&delta;}}_{\mathrm{st}}=y_{\max }=\frac{P_H{l}^3}{36\mathrm{EI}}=0.027\frac{P_H{l}^3}{\mathrm{EI}}---\left(16\right)$

Then the bendind rigidity equivalence of system is:

$k=\frac{P}{{\mathrm{\&delta;}}_{\mathrm{st}}}=\frac{36\mathrm{EI}}{l^3}---\left(17\right)$

In like manner, can get its cycle is:

$T=2\mathrm{\&pi;}\sqrt{\frac{w}{\mathrm{gk}}}=2\mathrm{\&pi;}\sqrt{\frac{{\mathrm{wl}}^3}{36\mathrm{EIg}}}---\left(18\right)$

Its natural frequency is:

$f_n=\frac{1}{2\mathrm{\&pi;}}\sqrt{\frac{36\mathrm{EIg}}{{\mathrm{wl}}^3}}---\left(19\right)$

By above analysis, the present invention has obtained the Flexural Equation (9) of drilling platform leg and the transverse vibration amplitude equation (11) of drilling platform, and this lays a good foundation and convenience is provided for the present invention analyzes drilling platform transverse vibration characteristic.

I) through type (11) as can be known, the lateral amplitude of vibration δ of drilling platform _StTransverse force P suffered with it _HBe directly proportional.This has also shown under the strong wind condition, the transverse force P that drilling platform is subjected to _HBig more, its lateral amplitude of vibration δ then _StAlso just big more.

Ii) through type (14) as can be known, the period T of drilling platform and deadweight w and 3/2 power that rises height degree l are directly proportional, this proves absolutely that rising height degree l has the greatest impact to period T.Promptly in the marine site, deep-sea or at drilling platform when the spud leg operation at top, height degree l is very big to cause period T long owing to rising, this conclusion meets the result that empirical observations draws.

The iii) lateral amplitude of vibration δ of drilling platform simultaneously _StAlso the bendind rigidity coefficient EI with spud leg is inversely proportional to, and this shows the big more then δ of EI _StMore little.

2, accurately calculate well location

As shown in Figure 3, be the x coordinate with the longitude, set up earth coordinates with the latitude for the y coordinate.O (x wherein ₀, y ₀) point is for predefined well location coordinate, (x, y) for rising the terrestrial coordinate that records well location behind the ship by prior art, b ' (x ', y ') is well location coordinate accurately to b.α is that (x y) departs from o (x to b ₀, y ₀) deflection, α ' is that b ' (x ', y ') departs from o (x ₀, y ₀) deflection.

The step of measuring accurate well location is as follows:

A) by the assay method of prior art obtain well location terrestrial coordinate b (x, y);

B) try to achieve the lateral amplitude of vibration δ of drilling platform by formula (11) in the direction of the wind comes from _St, δ _StComponent on the x axle is

δ _st(x)＝sin(α _w)δ _st (20)

Component on the y axle is

δ _st(y)＝cos(α _w)δ _st (21)

α wherein _wDeflection for wind direction;

C) calculate accurately well location coordinate b ' (x ', y '), x '=x-δ _St(x), x '=y-δ _St(y); B ' (x ', y ') departs from o (x ₀, y ₀) deflection be

${\mathrm{\&alpha;}}^{\&prime;}=\arctan \frac{x^{\&prime;}-x_0}{y^{\&prime;}-y_0}---\left(22\right).$

If (x y) is the average of the terrestrial coordinate that records in average period, lateral amplitude of vibration δ so to b _StJust should get the value substitution following formula of half.By above step, just can be in the hope of the accurate well location of drilling platform, thus effectively removed lateral amplitude of vibration δ _StInfluence, the difficulty that makes the tieback under water in later stage run into is solved.

3, specific embodiment

The spud leg of three spud leg drilling platform is a column type, and getting spud leg weight is 15160KN, its I=0.77 * 10 ^-3m ⁴, E=2.1 * 10 ⁸KN/m ²The scope that rises height degree l of drilling platform changes in 10 ~ 40m scope.Platform is estimated one's own ability when rising the ship operation and is that 33650KN, travelling load are 7500KN.Under the drilling operation condition, changing load is 12700KN.Suppose rising under the ship condition that changing load is 4000KN only, and under the drilling operation condition, changing load is fully loaded with 19500KN; Fixed load is fully loaded, adds 2000m* φ 127mm drill string (29kg/m) and 200m* φ 203mm drill collar (220kg/m) simultaneously, and its drilling tool general assembly (TW) is about 1000KN.

Different wind directions changes as shown in Figure 4, and when wind direction was N/S, the drilling platform wind area was: A _P=609m ²When wind direction was E/W, wind area was: A _P=516m ²When wind direction was N/E, wind area was: A _P=474m ²Ask when wind load during by 5 to 10 grades, the first step is asked the lateral amplitude of vibration δ of the horizontal direction that drilling platform produces _St, period T and natural frequency f _nSecond step was calculated well location coordinate accurately.

The first step is asked the lateral amplitude of vibration δ of the horizontal direction of drilling platform generation _St, period T and natural frequency f _n:

By known, rising under the ship operating condition, platform weight is:

W=platform deadweight+spud leg weight+rise ship changing load+travelling load

＝33650+15160+4000+7500＝6031000KN

Under the drilling operation condition, platform weight is:

W=platform deadweight+spud leg weight+drilling well changing load+travelling load

＝33650+15160+12700+7500＝6907000Kg

Supposition now rises height degree l=12m, 6 grades of wind-force (wind speed v=10.8-13.8m/sec), and wind direction is N/S.Rising under the ship state, is example with wind speed v=13.8m/sec.Result of calculation is shown in boldface letter in the table 1, and concrete solution procedure is as follows:

Lateral amplitude of vibration is by formula (16) as can be known:

${\mathrm{\&delta;}}_{\mathrm{st}}=\frac{{\mathrm{Pl}}^3}{36\mathrm{EI}}=\frac{300.7*{1200}^3}{36*2.1*{10}^6*77000}=0.11\mathrm{cm}$

Cycle is by formula (18) as can be known:

$T=2\mathrm{\&pi;}\sqrt{\frac{{\mathrm{wl}}^3}{36\mathrm{gEI}}}=2\mathrm{\&pi;}\sqrt{\frac{6031000*{1200}^3}{36*980*2.1*{10}^6*77000}}=8.49\sec$

Natural frequency by formula (19) as can be known

$f_n=\frac{1}{T}=\frac{1}{2\mathrm{\&pi;}}\sqrt{\frac{36\mathrm{EIg}}{{\mathrm{wl}}^3}=\frac{1}{2\mathrm{\&pi;}}}\sqrt{\frac{36*2.1*{10}^6*77000*980}{6031000*{1200}^3}}=0.12{\sec }^{-1}$

The different lateral amplitude of vibration δ that rise height degree and N/S, E/W, three wind directions of N/E under all the other conditions _St, period T, natural frequency f _nSee table 1～table 6 for details:

Table 1: rise ship state bow to N, wind direction N/S

Rise height degree l m	Storm δ st cm	Strong gale δ st cm	Fresh gale δ st cm	Moderate gale δ st cm	Strong breeze δ st cm	Period T sec	Natural frequency f n 1/sec
								10	0.2	0.095	0.06	0.04	0.02	6.46	0.15
10	0.3	0.137	0.09	0.06	0.04	6.46	0.15
								12	0.3	0.160	0.11	0.06	0.04	**8.49	0.12
12	0.4	0.237	0.16	0.11	0.06	**8.49	0.12
								14	0.5	0.254	0.17	0.10	0.06	10.70	0.09
14	0.7	0.376	0.25	0.17	0.10	10.70	0.09
								15	0.7	0.31	0.21	0.13	0.07	**11.86	0.08
15	0.9	0.46	0.31	0.21	0.12	**11.86	0.08
								20	1.6	0.74	0.50	0.30	0.16	18.26	0.05
20	2.1	1.10	0.74	0.49	0.29	18.26	0.05
								30	5.3	2.50	1.69	1.01	0.55	33.55	0.03
30	7.0	3.70	2.5	1.65	0.99	33.55	0.03
								40	12.6	5.92	4.0	2.39	1.31	51.66	0.02
40	16.5	8.78	5.9	3.90	2.35	51.66	0.02
								50	24.6	11.56	7.8	4.67	2.56	72.19	0.01
50	32.3	17.15	11.6	7.62	4.58	72.19	0.01

*----is the common mean wave period in the South Sea and marine site, the Bohai Sea, and it is 12sec that normal conditions are got the South Sea, and the Bohai Sea is 8sec

Table 2: drilling state, bow be to N, wind direction N/S

Rise height degree l m	Storm δ st cm	Strong gale δ st cm	Fresh gale δ st cm	Moderate gale δ st cm	Strong breeze δ st cm	Period T sec	Natural frequency f n 1/sec
								10	0.2	0.07	0.05	0.04	0.02	6.91	0.14
10	0.3	0.10	0.07	0.06	0.03	6.91	0.14
								12	0.3	0.12	0.08	0.06	0.03	**9.08	0.11
12	0.4	0.18	0.12	0.11	0.05	**9.08	0.11
								14	0.5	0.19	0.13	0.10	0.04	**11.45	0.09
14	0.7	0.28	0.19	0.17	0.08	**11.45	0.09
								15	0.7	0.24	0.16	0.13	0.05	**12.69	0.08
15	0.9	0.35	0.24	0.21	0.09	**12.69	0.08
								20	1.6	0.56	0.38	0.30	0.12	19.54	0.05
20	2.1	0.83	0.56	0.49	0.22	19.54	0.05
								30	5.3	1.89	1.28	1.01	0.42	35.91	0.03
30	7.0	2.80	1.89	1.65	0.75	35.91	0.03
								40	12.6	4.47	3.03	2.39	0.99	55.28	0.02
40	16.5	6.63	4.47	3.90	1.77	55.28	0.02
								50	24.6	8.74	5.92	4.67	1.93	77.26	0.01
50	32.3	12.95	8.74	7.62	3.46	77.26	0.01

*----is the common mean wave period in the South Sea and marine site, the Bohai Sea, and it is 12sec that normal conditions are got the South Sea, and the Bohai Sea is 8sec

Table 3: rise the ship state, bow is to N, wind direction E/W

Rise height degree l m	Storm δ st cm	Strong gale δ st cm	Fresh gale δ st cm	Moderate gale δ st cm	Strong breeze δ st cm	Period T sec	Natural frequency f n 1/sec
								10	0.167	0.078	0.053	0.032	0.017	6.46	0.15
10	0.22	0.140	0.08	0.05	0.03	6.46	0.15
								12	0.29	0.135	0.09	0.05	0.03	**8.49	0.12
12	0.38	0.242	0.14	0.09	0.05	**8.49	0.12
								14	0.46	0.215	0.15	0.09	0.05	10.70	0.09

14	0.60	0.384	0.22	0.14	0.09	10.70	0.09
								15	0.56	0.24	0.18	0.11	0.06	**11.86	0.08
15	0.74	0.35	0.26	0.17	0.10	**11.86	0.08
								20	1.33	0.56	0.43	0.25	0.14	18.26	0.05
20	1.75	0.83	0.63	0.41	0.25	18.26	0.05
								30	4.50	1.89	1.44	0.85	0.47	33.55	0.03
30	5.91	2.80	2.1	1.39	0.84	33.55	0.03
								40	10.68	4.47	3.4	2.02	1.11	51.66	0.02
40	14.00	6.63	5.0	3.31	1.99	51.66	0.02
								50	20.85	8.74	6.6	3.95	2.17	72.19	0.01
50	27.35	12.95	9.8	6.46	3.88	72.19	0.01

*----is the common mean wave period in the South Sea and marine site, the Bohai Sea, and it is 12sec that normal conditions are got the South Sea, and the Bohai Sea is 8sec

Table 4: drilling state, bow be to N, wind direction E/W

Rise height degree l m	Storm δ st cm	Strong gale δ st cm	Fresh gale δ st cm	Moderate gale δ st cm	Strong breeze δ st cm	Period T sec	Natural frequency f n 1/sec
								10	0.167	0.078	0.053	0.053	0.015	**6.91	0.14
10	0.22	0.116	0.08	0.08	0.03	**6.91	0.14
								12	0.38	0.201	0.14	0.14	0.05	**9.08	0.11
12	0.38	0.201	0.14	0.14	0.05	**9.07	0.11
								14	0.60	0.319	0.22	0.22	0.08	**11.43	0.09
14	0.60	0.319	0.22	0.22	0.08	**11.42	0.09
								15	0.56	0.265	0.18	0.18	0.05	**12.69	0.08
15	0.74	0.392	0.26	0.26	0.09	**12.69	0.08
								20	1.33	0.627	0.43	0.43	0.12	19.54	0.05
20	1.75	0.930	0.63	0.63	0.22	19.54	0.05
								30	4.50	2.117	1.44	1.44	0.42	35.91	0.03
30	5.91	3.138	2.12	2.12	0.75	35.91	0.03
								40	10.68	5.017	3.40	3.40	0.99	55.28	0.02

40	14.00	7.438	5.02	5.02	1.77	55.28	0.02
								50	20.85	9.799	6.65	6.65	1.93	77.26	0.01
50	27.35	14.528	9.80	9.80	3.46	77.26	0.01

*----is the common mean wave period in the South Sea and marine site, the Bohai Sea, and it is 12sec that normal conditions are got the South Sea, and the Bohai Sea is 8sec

Table 5: rise the ship state, bow is to N, wind direction N/E

Rise height degree l m	Storm δ st cm	Strong gale δ st cm	Fresh gale δ st cm	Moderate gale δ st cm	Strong breeze δ st cm	Period T sec	Natural frequency f n 1/sec
								10	0.2	0.072	0.05	0.03	0.02	6.46	0.15
10	0.2	0.107	0.07	0.05	0.03	6.46	0.15
								12	0.3	0.124	0.08	0.05	0.03	**8.49	0.12
12	0.3	0.184	0.12	0.08	0.05	**8.49	0.12
								14	0.4	0.198	0.13	0.08	0.04	10.70	0.09
14	0.6	0.293	0.20	0.13	0.08	10.70	0.09
								15	0.5	0.24	0.16	0.10	0.05	**11.86	0.08
15	0.7	0.36	0.24	0.16	0.10	**11.86	0.08
								20	1.2	0.58	0.39	0.23	0.13	18.26	0.05
20	1.6	0.85	0.58	0.38	0.23	18.26	0.05
								30	4.1	1.94	1.32	0.78	0.43	33.55	0.03
30	5.4	2.88	1.9	1.28	0.77	33.55	0.03
								40	9.8	4.61	3.1	1.86	1.02	51.66	0.02
40	12.9	6.83	4.6	3.04	1.83	51.66	0.02
								50	19.2	9.00	6.1	3.63	1.99	72.19	0.01
50	25.1	13.35	9.0	5.93	3.57	72.19	0.01

*----is the common mean wave period in the South Sea and marine site, the Bohai Sea, and it is 12sec that normal conditions are got the South Sea, and the Bohai Sea is 8sec

Table 6: drilling state, bow be to N, wind direction N/E

Rise height degree l m

Storm δ st cm

Strong gale δ st cm

Fresh gale δ st cm

Moderate gale δ st cm

Strong breeze δ st cm

Period T sec

Natural frequency f n 1/sec

10	0.2	0.072	0.05	0.03	0.02	**6.91	0.14
								10	0.2	0.107	0.07	0.05	0.03	**6.91	0.14
12	0.3	0.184	0.12	0.08	0.05	**9.08	0.14
								12	0.3	0.184	0.12	0.08	0.05	**9.07	0.11
14	0.6	0.293	0.20	0.13	0.08	**11.43	0.11
								14	0.6	0.293	0.20	0.13	0.08	**11.42	0.09
15	0.5	0.243	0.16	0.10	0.05	12.69	0.09
								15	0.7	0.360	0.24	0.16	0.10	12.69	0.08
20	1.2	0.576	0.39	0.23	0.13	19.54	0.08
								20	1.6	0.854	0.58	0.38	0.23	19.54	0.05
30	4.1	1.944	1.32	0.78	0.43	35.91	0.05
								30	5.4	2.883	1.94	1.28	0.77	35.91	0.03
40	9.8	4.609	3.13	1.86	1.02	55.28	0.03
								40	12.9	6.833	4.61	3.04	1.83	55.28	0.02
50	19.2	9.001	6.10	3.63	1.99	77.26	0.02
								50	25.1	13.346	9.00	5.93	3.57	77.26	0.01

*----is the common mean wave period in the South Sea and marine site, the Bohai Sea, and it is 12sec that normal conditions are got the South Sea, and the Bohai Sea is 8sec

Observation table 1～table 6 can be found:

1) for three spud leg drilling platform, the transverse vibration amplitude δ of platform _StBe directly proportional with rising height degree l, promptly to rise the height degree high more for spud leg, then the amplitude δ of drilling platform _StJust big more.In at table 1, when rising height degree l10m, under strong breeze speed condition, amplitude δ _StBe 0.02cm; But when spud leg rises the height degree and increases to 20m, amplitude δ _StReached 0.16m, be spud leg and rise 1 times of height degree increase, amplitude δ _StThen increase about 8 times; As when rising the height degree and reach 40m, amplitude δ _StBe 1.31cm, also be about 8.2 times.

2) for three drilling platform, amplitude δ _StBe varied to direct ratio with the increase of wind-force, promptly wind-force is big more, amplitude δ _StAlso big more.In at table 1, same rising under the height degree condition, when rising height degree l and being 10m, during strong breeze speed, amplitude δ _StBe 0.02cm, during storm speed, amplitude δ _StIncrease by 10 times, reach 0.2cm; In like manner, when rising the height degree and be 40m, during strong breeze speed, amplitude δ _StBe 0.16cm, and storm when speed amplitude δ _StReach 1.6cm.

3) according to the setting of this subject design conditions, bow is to being N, is located at wind direction when being respectively N/S, E/W, N/W (N/E) direction, the front face area A of drilling platform _PDifference, then its amplitude δ _StChange thereupon.According to amplitude δ _StThe wind direction ordering from big to little correspondence be followed successively by: N/S, E/W and N/E (N/W).And have the amplitude of amplitude ratio E/W direction of N/S direction high by about 15%, the amplitude of the amplitude ratio N/E direction of E/W direction is high by about 8%.

4) the present invention has determined to rise the selection foundation of measuring and calculating well location under the ship state.In at table 1: rising under the ship state, bow is to N, wind direction N/S, and three drilling platform:

When rising height degree l and be 12m, its period T is 8.49sec, because about Bohai Sea Area wave 8sec average period.When rising height degree l and be 15m, its period T is 11.86sec.Because Nanhai area wave average period is about 12sec.Therefore rise in marine site, the South Sea and should note avoiding 12m and this resonance height of 15m when calculating well location under the ship state.

5) the present invention has determined the drilling state selection foundation of measuring and calculating well location down.In at table 6: under drilling state, bow is to N, wind direction N/E: three drilling platform:

When rising height degree l and be 11-12m, its period T is 7.97-9.08sec.Because Bohai Sea Area wave average period is about 8sec, therefore should note avoiding this resonance altitude range of 11-12m rising ship time, when calculating, well location to take into full account effect on amplitude simultaneously.When rising height degree l and be 11-14m, its period T is 9.08-11.43sec.Because Nanhai area wave average period is about 12sec, therefore should note avoiding this resonance altitude range rising ship time, when calculating, well location to take into full account effect on amplitude simultaneously.

Second step was calculated well location coordinate accurately:

According to the result in the table 1: the well location coordinate of setting when in place at sea as three spud leg drilling platform is o (x ₀, y ₀), x ₀=4429932.41, y ₀=592734.32, rise height degree l=40m.When wind-force reaches 8 grades, record well location terrestrial coordinate b (x, y), x=4429935.13, y=592743.00 departs from and sets well location o (x ₀, y ₀) direction angle alpha=287.4 °, well location offset distance d=9.1m (as shown in Figure 4).Ask consider platform vibration after, pithead position coordinate accurately.

Separate: table look-up 1 as can be known, under these conditions, drilling platform lateral amplitude of vibration δ _StBe 8.78～5.92cm, now make δ _St=8.78cm.

With reference to this moment wind direction and bow to, the deflection of wind direction is α _w, by formula (20) and (21) as can be known, lateral amplitude of vibration δ _StX axle component δ _St(x)=sin (α _w) δ _St=8.78cm, y axle component δ _St(y)=cos (α _w) δ _St=0.Then:

x′＝x-δ _st(x)＝4429935.04

y′＝y＝592743.0

By formula (22) as can be known, b ' (x ', y ') departs from o (x ₀, y ₀) deflection

Then terrestrial coordinate deflection error is: α-α '=0.7 °.

The present invention is according to different drilling operation states: rise ship state, drilling state, different wind directions and different wind scales thereof, the different height degree l that rise; Calculate three drilling platform lateral amplitude of vibration δ _StAnd period T.And need be with the well location deduction amplitude δ that calculates in average period _StInfluence after, just can obtain pithead position coordinate accurately.The present invention has given prominence in the on-the-spot use and has been illustrated and uses in the marine site at the Bohai Sea and South Sea concrete condition, the present invention makes self-elevating drilling platform horizontal vibration amplitude and accurate measuring and calculating well location that guide of theory arranged, and at sea drilling engineering is of great immediate significance in using.

Claims (4)

1, a kind of method of accurate measuring and calculating self-elevating drilling platform well position, it may further comprise the steps:

1) sets up the lateral amplitude of vibration δ of drilling platform _St, period T and natural frequency f _nEquation

${\mathrm{\&delta;}}_{\mathrm{st}}=\frac{P_H\&CenterDot;l^3}{12\mathrm{nEI}}$

$T=2\mathrm{\&pi;}\sqrt{\frac{w}{\mathrm{gk}}}$

$f_n=\frac{1}{T}=\frac{1}{2\mathrm{\&pi;}}\sqrt{\frac{12\mathrm{nEIg}}{w{l}^3}}$

In the formula: P _H---drilling platform is lateral stressed

L---rise the height degree

N---spud leg number

E---elastic modulus is got E=2.1 * 106kg/cm to steel ²

I---polar moment of inertia is to circular spud leg

$I=\frac{\mathrm{\&pi;}}{64}({\mathrm{OD}}^4-{\mathrm{ID}}^4)\left[{\mathrm{cm}}^4\right]$

OD---external diameter

ID---internal diameter

W---drilling platform deadweight

G---acceleration of gravity

2) calculate well location accurately

A, suppose that the well location coordinate that prior art records is that (x, y), the well location coordinate of setting is o (x to b ₀, y ₀), α _wDeflection for wind direction;

B, try to achieve drilling platform by step 1) and determining the lateral amplitude of vibration δ of wind direction _St, δ then _StComponent on the x axle is

δ _st(x)＝sin(α _w)δ _st

Component on the y axle is

δ _st(y)＝cos(α _w)δ _st

C, calculate accurately well location coordinate b ' (x ', y '), wherein x '=x-δ _St(x), x '=y-δ _St(y); B ' (x ', y ') departs from o (x ₀, y ₀) deflection be

${\mathrm{\&alpha;}}^{\&prime;}=\arctan \frac{x^{\&prime;}-x_0}{y^{\&prime;}-y_0}.$

2, a kind of method of accurate measuring and calculating self-elevating drilling platform well position is characterized in that: in the described step 1), and P _HComputing method as follows:

$P_H=\frac{r{v}^2}{2g}{c}_D{A}_p$

In the formula: r---atmospheric density

V---wind speed

c _D---resistance coefficient

A _p---be the projection of drilling platform bulk area on the wind direction vertical plane.

3, a kind of drill string and self-elevating drilling platform of preventing as claimed in claim 1 produces the method for resonance, it is characterized in that: in the described step 1), and three spud leg drilling platform, then n=3.

4, a kind of drill string and self-elevating drilling platform of preventing as claimed in claim 1 produces the method for resonance, it is characterized in that: described step 2), (x y) adopts the average of the terrestrial coordinate that records in average period, then lateral amplitude of vibration δ to b _StShould get half.

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