CN104570117A - Datum correction method for stack velocity of oil exploration - Google Patents

Abstract

The invention provides a datum correction method for a stack velocity in oil exploration. Seismic data are acquired and then processed into the stack velocity; united datum correction is conducted on the stack velocity; united datum correction computation of zero-offset travel time is carried out; TV pairs of united datum correction are calculated; the datum correction for the stack velocity is fulfilled. The method can be used for correcting the stack velocity corresponding to a CMP surface to the united datum directly, thereby being low in data processing workload and less in manual operation error.

Description

A kind of method of petroleum prospecting stack velocity base-level correction

Technical field

This patent belong to be processed into picture and structure elucidation technology, be the method for a kind of petroleum prospecting stack velocity base-level correction of correction.

Background technology

Stack velocity is the speed of petroleum geology exploration data process stacking image, and corresponding face is the face (being commonly referred to as CMP face) referenced by stack velocity analysis.Meanwhile, it is again the initial velocity of poststack, migration before stack, is also the basal rate in structure elucidation technology.Corresponding to skew and structure elucidation, face is uniform reference surface, and therefore, stack velocity will carry out being corrected to uniform reference surface by CMP face.

At present, stack velocity directly can not be corrected to uniform reference surface by CMP face, when stack velocity being carried out building as the initial velocity of pre-stack time migration, again make stack velocity spectrum with the geological data being corrected to uniform reference surface and picking stack completes, this significantly increases workload, and also imprecision theoretically.Another kind method utilizes the method for layer control that stack velocity is corrected in uniform reference surface by CMP face, first this method utilizes the layer position of superposition of data, calculate interval velocity by DIX formula, then add the layer corresponding to LFC low-frequency correction amount, then go out stack velocity by DIX formula inverse.Due to DIX formula corresponding be root-mean-square velocity, so the stack velocity error of the interval velocity just calculated by it and inverse is all comparatively large, and need the layer position of explaining stacked section, workload is also very large.In structure elucidation, the basic data usually utilized is migrated section (offset data body) and stack velocity, is also first one-tenth stack velocity is transformed into interval velocity, then the basic colonel of interval velocity in uniform reference surface.

Owing to directly can not be corrected to uniform reference surface by the stack velocity that CMP face is corresponding, the layer position of transitional layer speed will be picked up from stacked section, increase artificial operate miss.

Summary of the invention

The object of the invention is to provide that a kind of data processing work amount is little, the method for the petroleum prospecting stack velocity base-level correction that reduces artificial operate miss.

The concrete steps that the present invention realizes comprise:

1) field acquisition geological data;

2) by the stack velocity that usual way process is formed, stack velocity tv couple: t is obtained on CMP face _0i--v _0i, (tv to referring to a time t, corresponding a speed v)

Whilst on tour t when calculating offset distance is L _li:

In formula: i is the order that tv is right, t _0ifor the whilst on tour of the zero-offset in corresponding CMP face, v _0ifor the stack velocity of its correspondence, L is any offset distance in geological data, t _lifor being the set with identical central point road at CMP(CMP) offset distance L is corresponding on face whilst on tour;

3) adopt following formula to stack velocity uniform reference surface correction calculation:

$v_{1i}=\frac{v_{0i}{t}_{0i}\sqrt{{(v_{0i}{t}_{0i}+\mathrm{delt}\·v_r)}^2+{(L+\frac{\mathrm{delt}\·v_r\·L}{v_{0i}{t}_{0i}})}^2}}{v_{0i}{t}_{0i}{t}_{\mathrm{Li}}+\mathrm{delt}\·\sqrt{L^2+v_{0i}^2{t}_{0i}^2}}$

In formula: v _1ifor the stack velocity after uniform reference surface correction, delt is the correcting value of CMP face to uniform reference surface, v _rfor replacement velocity;

4) the uniform reference surface correction calculation of zero-offset whilst on tour is carried out, t _01i=t _0i+ delt, in formula: t _01ifor the whilst on tour of the corresponding zero-offset of uniform reference surface;

5) TV couple: the t of uniform reference surface correction is calculated _01i--v _1i, in formula: t _01ifor the whilst on tour of zero-offset corresponding to uniform reference surface, v _1ifor the stack velocity that uniform reference surface is corresponding, complete stack velocity base-level correction.

The present invention directly to the correction of uniform reference surface, provides that a kind of data processing work amount is little, the method for the petroleum prospecting stack velocity base-level correction that reduces artificial operate miss by stack velocity corresponding to CMP face.

Accompanying drawing explanation

Fig. 1 be on usual method CMP face stack velocity tv to figure.

Embodiment

The concrete steps of the present invention's realization are described in detail below in conjunction with accompanying drawing:

1, field acquisition geological data;

2, by the stack velocity that usual way (as Fig. 1) process is formed, stack velocity tv is obtained on CMP face to (as table 1): t _0i--v _0i,

Whilst on tour t when calculating offset distance is L _li:

In formula: i is the order that tv is right, t _0ifor the whilst on tour of the zero-offset in corresponding CMP face, v _0ifor the stack velocity of its correspondence, L is any offset distance in geological data, t _lifor the whilst on tour that offset distance L on CMP face is corresponding;

Fig. 1 obtains the figure that on CMP face, stack velocity tv is right, and the ordinate of figure is the time, and horizontal ordinate is speed, and the point in figure is the speed point of pickup, and time and the speed of this some correspondence just obtain stack velocity tv couple on CMP face.

Table 1 is the numerical tabular that on CMP face, stack velocity tv is right, the zero-offset time for corresponding CMP face that T list is shown, the stack velocity for corresponding CMP face that V list is shown.

Table 1

3, adopt following formula to stack velocity uniform reference surface correction calculation:

$v_{1i}=\frac{v_{0i}{t}_{0i}\sqrt{{(v_{0i}{t}_{0i}+\mathrm{delt}\·v_r)}^2+{(L+\frac{\mathrm{delt}\·v_r\·L}{v_{0i}{t}_{0i}})}^2}}{v_{0i}{t}_{0i}{t}_{\mathrm{Li}}+\mathrm{delt}\·\sqrt{L^2+v_{0i}^2{t}_{0i}^2}}----\left(2\right)$

In formula: v _1ifor the stack velocity after uniform reference surface correction, delt is the correcting value of CMP face to uniform reference surface, v _rfor replacement velocity;

4) the uniform reference surface correction calculation of zero-offset whilst on tour is carried out, t _01i=t _0i+ delt---(3), in formula: t _01ifor the whilst on tour of the corresponding zero-offset of uniform reference surface;

5) TV couple: the t of uniform reference surface correction is calculated _01i--v _1i, in formula: t _01ifor the whilst on tour of zero-offset corresponding to uniform reference surface, this value is calculated by formula 3; v _1ifor the stack velocity that uniform reference surface is corresponding, this value is calculated by formula 2.Now just complete by stack velocity corresponding to CMP face directly to the correction of uniform reference surface.

Table 2 is results of the present invention, be the value of table 1 through output of the present invention, the time of corresponding uniform reference surface zero-offset is shown in T list, and the stack velocity of corresponding uniform reference surface is shown in V list.

Table 2

	T	V
			1	769	2697
2	969	3057
			3	1294	3314
4	1494	3406
			5	1719	3558
6	1919	3652
			7	2119	3581
8	2344	3540
			9	2669	3417
10	2894	3523
			11	3119	3672

Table 3

1	2	3	4	5	6	7	8
										Cmp face	Cmp face	Cmp face	Cmp face	Uniform reference surface	Uniform reference surface
delt(ms)	vr(ms)	t0i(ms)	v0i(m/s)	L(m)	TLi(s)	V1i(m/s）	T01i（ms)
								444	2000	525	3950	50	0.5251526	3056.50155	969
444	2000	525	3950	1000	0.5828527	3056.50155	969
								444	2000	525	3950	2000	0.7293793	3056.50155	969
444	2000	525	3950	4000	1.1406584	3056.50155	969
								444	2000	525	3950	5000	1.3703767	3056.50155	969
444	2000	525	3950	6000	1.6071551	3056.50155	969
								444	2000	2675	3950	50	2.6750299	3672.41103	3119
444	2000	2675	3950	1000	2.6869532	3672.41103	3119
								444	2000	2675	3950	2000	2.7224978	3672.41103	3119
444	2000	2675	3950	4000	2.8602625	3672.41103	3119
								444	2000	2675	3950	5000	2.9593804	3672.41103	3119
444	2000	2675	3950	6000	3.0761904	3672.41103	3119

Table 3 is the stack velocity process tables being corrected to uniform reference surface by CMP face calculated with the present invention.

For second in table 1 (525-3950) and last (2675-3950) TV to:

Wherein the 1st be classified as base-level correction amount, the 2nd and be classified as replacement velocity, the 3rd row, the 4th are classified as stack velocity tv couple: t0i-v0i corresponding to CMP face, and above data are known.It is arbitrary data within the scope of offset distance that 5th row, the 6th row are respectively the right different offset distance L(L of stack velocity tv corresponding to CMP face, actual computation is only appointed to a value just) and whilst on tour, 7th is classified as the stack velocity V1i being corrected to uniform reference surface by CMP, and the 8th is classified as the zero-offset time T that CMP is corrected to uniform reference surface _01ias can be seen from the table, corresponding to the same TV in CMP face to (525-3950,2675-3950) different offset distance L(50,1000,2000,4000,5000,6000) stack velocity (the 7th row) of uniform reference surface that calculates is equal, completes and corrected by the stack velocity of CMP face to uniform reference surface.

Can see from this table: by known base-level correction amount, replacement velocity, original stack velocity tv couple, the stack velocity of uniform reference surface calculated any given offset distance L this method is unique, be consistent with the geophysical significance of stack velocity, thus describe correctness of the present invention.

Claims (1)

1. a method for petroleum prospecting stack velocity base-level correction, feature is realized by following steps:

1) field acquisition geological data;

2) by the stack velocity that usual way process is formed, stack velocity tv couple: t is obtained on CMP face _0i--v _0i,

Whilst on tour t when calculating offset distance is L _li:

In formula: i is the order that tv is right, t _0ifor the whilst on tour of the zero-offset in corresponding CMP face, v _0ifor the stack velocity of its correspondence, L is any offset distance in geological data, t _lifor the whilst on tour that offset distance L on CMP face is corresponding;

3) adopt following formula to stack velocity uniform reference surface correction calculation:

$v_{1i}=\frac{v_{0i}{t}_{0i}\sqrt{{(v_{0i}{t}_{0i}+\mathrm{delt}\·v_r)}^2+{(L+\frac{\mathrm{delt}\·v_r\·L}{v_{0i}{t}_{0i}})}^2}}{v_{0i}{t}_{0i}{t}_{\mathrm{Li}}+\mathrm{delt}\·\sqrt{L^2+v_{0i}^2{t}_{0i}^2}}$

In formula: v _1ifor the stack velocity after uniform reference surface correction, delt is the correcting value of CMP face to uniform reference surface, v _rfor replacement velocity;

4) the uniform reference surface correction calculation of zero-offset whilst on tour is carried out, t _01i=t _0i+ delt, in formula: t _01ifor the whilst on tour of the corresponding zero-offset of uniform reference surface;

5) TV couple: the t of uniform reference surface correction is calculated _01i--v _1i, in formula: t _01ifor the whilst on tour of zero-offset corresponding to uniform reference surface, v _1ifor the stack velocity that uniform reference surface is corresponding, complete stack velocity base-level correction.