CN1239922C

CN1239922C - Artificial source time frequency electro magnetic bathymetry

Info

Publication number: CN1239922C
Application number: CN 03150098
Authority: CN
Inventors: 何展翔
Original assignee: China National Petroleum Corp; BGP Inc
Current assignee: China National Petroleum Corp; BGP Inc
Priority date: 2003-08-01
Filing date: 2003-08-01
Publication date: 2006-02-01
Anticipated expiration: 2023-08-01
Also published as: CN1580818A

Abstract

The present invention achieves the unification of an exploration method of electromagnetic depth measurement in a frequency field method and a time field method. The law of a whole frequency spectrum is researched by exciting and receiving a series of frequency (period) pulses; meanwhile, the signal attenuation law of each frequency (period) is researched; reflected underground information is deepened step by step from a short period to a long period, and superimposition for the information can improve exploration precision; a frequency field and a time field can be validated mutually via the time-frequency conversion of the frequency field and the time field; the exploration precision is improved greatly; particularly, various kinds of information can be researched and the exploration precision can be improved via two processing means of the time field and the frequency field in data processing. The present invention is a novel electromagnetic method of depth measurement with multiple pulse excitation, multiple components of collection and multiple parameters of research for achieving multiple requirements of exploration targets, which belongs to an exploration method for geophysics; the present invention can be used for the exploration of underground targets with an electrical property difference, and is mainly used for the exploration of oil gas, mineral products and geothermal resources.

Description

Artificial source's temporal frequency electromagnetic sounding method

Relate to the field

The present invention relates to geophysical survey, is a kind of electromagnetic sounding method of exploration.

Background technology

At present, in oil gas, mineral products and underground geothermal resource exploration, artificial source's electromagnetic method is used more.But existing method all is frequency field or time domain method.Promptly or a frequency of a frequency excite measurement, as controlled source audio-frequency magnetotelluric method (CSAMT) (CSAMT); Or excite a pulse (square wave) to measure die-away curve in time after its outage, as long offset distance transient electromagnetic method (LOTEM).In addition, the existing methods measurement parameter only limits to an electric field, a magnetic-field component, as the CSAMT method; Or only survey a vertical magnetic field, as the LOTEM method.The physical parameter of its research is single, only limits to resistance parameter.Therefore, these methods require to exist gap, method itself to be difficult to the geological problem that satisfactory solution exists at aspects such as ability that solves geological problem and precision with actual!

Summary of the invention

At the problem that exists in the background technology, the present invention still adopts long lead galvanic couple source or big loop line magnetic couple source excitation when data acquisition, adopt many survey stations to arrange the working method that receives.Each survey station is made up of electric acquisition station and magnetic acquisition station, comprises 5 component tensors, i.e. two horizontal magnetic fields and vertical magnetic field: Hx, a Hy and Hz, two horizontal component of electric field: Ex and Ey.The survey station spacing quantity of hour magnetic acquisition station can reduce, and can lay a three-component magnetic acquisition station by several survey stations.Mode of excitation adopts zero passage or non-zero passage square wave.Excite from the high frequency to the low frequency and continuous, each frequency repeats to excite several times, the height setting of multiplicity video frequency, and the multiplicity of high frequency is many, mostly is most 1024 times, the low repetition of low frequency, minimum is 3 times.Receiving system receives all signals that each frequency repeats to excite by GPS synchronously with emission.

Signal in indoor each frequency to each field component superposes, and improves signal quality.Signal to each frequency record carries out spectrum analysis, obtains the fundamental frequency and the harmonic wave thereof of each frequency signal.Frequency is carried out above-mentioned processing one by one, gathers the frequency spectrum of all signals then, obtains the frequency spectrum from the high frequency to the low frequency signal, is used to study the rule of the entire spectrum of each field component.

This method has realized the unification of frequency field method and time domain method.The information of two, 30 frequencies that this obtains with CSAMT is compared and is wanted many 10 times, and its quality of data and reliability also improve greatly.Simultaneously the signal after each frequency stack is pressed the research of time domain transient law.The attenuation law of each periodic signal all reflects the electrical property feature from shallow to dark, and from the short period to the long period, the subsurface information that is reflected will progressively be deepened.Stack to these information can further improve signal quality, thereby the stacking fold of shallow-layer information is many, deep layer information stacking fold is few relatively, and this compares with LOTEM method simple signal single record, and its signal quality is greatly improved.Can provide the transient electromagnetic information of a plurality of single-frequency (cycle square wave) to the analysis of each frequency signal, its quantity of information is wanted many several times than LOTEM like this.And the signal of time domain and frequency field two aspects can verify mutually, improves surveying accuracy widely.In addition, the simple component measurement is changed into five components, promptly measure three-component magnetic field (Hx, Hy, Hz) and two horizontal component of electric fields (Ex, Ey), the information of each field component reflection is different, propagation and induction rule that the combination of five field components can complete description surface em field.Because high-quality has write down five field component information, can increase known equation element in the solving equation group in the modeling effort of data FORWARD AND INVERSE PROBLEMS, reduce the nonuniqueness of separating, accelerate the simulation convergence.The FORWARD AND INVERSE PROBLEMS modeling effort can independently be carried out in frequency field and time domain, the inversion result of acquisition can comparative study in the hope of the best.Study a plurality of parameters besides simultaneously: electric field and magnetic field, resistivity (electricity is led) and polarizability, and organize phase place more, what these parameters reflected is the different aspect of subsurface rock physical characteristics, by these metrical informations can be tighter the underground rerum natura model of inverting reconstruct, as resistivity, polarizability with the transitivity interface, the accuracy that comprehensively helps improving reconstruction model of multiple parameter.Therefore, this method has the advantage of frequency field method and time domain method two class methods concurrently, and have the data quality that is higher than both far away and handle the advantage of explaining, make in the Data Processing territory and two kinds of processing means of frequency field if having time, the multiple physical properties of rock of The Characteristics that various of comprehensive utilization is arranged, the multiple means of the most effective raising surveying accuracy.As seen this method be a kind of pulse excitation various, gather many components, the research multiparameter realizes the novel high-precision electromagnetic sounding method that many exploration targetss require.

The explanation of accompanying drawing subordinate list:

The data acquisition of Fig. 1 long lead galvanic couple source excitation is provided with figure

The collection of the big loop line Magnetic Field Source of Fig. 2 excitation data is provided with figure

The waveform of Fig. 3 excitation pulse, wherein a, b, c, d are 4 kinds of different excitation waveform

The distribution example in table 1 excitation waveform frequency and cycle, wherein highest frequency is 256Hz, the maximum excitation cycle is 1024 seconds.

Concrete enforcement

Embodiment 1 (Fig. 1): long lead galvanic couple source excitation,, certain electromagnetic field of laying at a distance receives survey station in distance galvanic couple source, adopts 5 component tensor survey stations.The direction of measurement that receives survey station electromagnetic field horizontal component is parallel and vertical with long lead galvanic couple source.Excitation waveform is 1: 1 a positive and negative square wave of dutycycle (Fig. 3 d), and the highest frequency that transmits is 256Hz, and low frequency is 1024 seconds.From low frequency to high frequency continuous agitation.Each frequency of low-frequency range repeats to excite 3 times, and each frequency of high band repeats to excite 1024 times, between increase progressively (seeing Table 1) gradually.Superpose at indoor signal, thereby obtain electromagnetic field 5 component signals: Ex, Ey, Hx, Hy and Hz each each frequency of field component.By to the underground rerum natura model of the inverting reconstruct of these field component information, comprise the resistivity section that reflects underground electric conductivity, reflect the polarizability section of underground electric polarization characteristic and the electrical interface of reflection subsurface resistivity sudden change.

Embodiment 2 (Fig. 2): big loop line Magnetic Field Source excites, and lays electromagnetic field and receive survey station in big Loop source, adopts 5 component tensor survey stations.It is parallel or vertical with big loop line Magnetic Field Source to receive survey station electromagnetic field horizontal component direction of measurement.Excitation waveform is dutycycle 1: 1: 1: (Fig. 3 a), the highest frequency that transmits is 256Hz to 1 positive and negative square wave, and low frequency is 1024 seconds.(see Table 1) from low frequency to high frequency continuous agitation, each frequency of low-frequency range repeats to excite 3 times, and each frequency of high band repeats to excite 1024 times, between increase progressively gradually.Superpose at indoor signal, thereby obtain electromagnetic field 5 component signals: Ex, Ey, Hx, Hy and Hz each each frequency of field component.By to the underground rerum natura model of the inverting reconstruct of these field component information, comprise the resistivity section that reflects underground electric conductivity, reflect the polarizability section of underground electric polarization characteristic and the electrical interface of reflection subsurface resistivity sudden change.

Subordinate list 1

Sequence number	Frequency/period	Unit	Multiplicity
Sequence number	Frequency/period	Unit	Multiplicity		1	256.00	HZ	1024
2	215.28	HZ	1024		1	256.00	HZ	1024
2	215.28	HZ	1024	3	181.06	HZ	1024
4	152.23	HZ	512	3	181.06	HZ	1024
4	152.23	HZ	512	5	128.00	HZ	512
6	107.64	HZ	512	5	128.00	HZ	512
6	107.64	HZ	512	7	90.50	HZ	256
8	76.61	HZ	256	7	90.50	HZ	256
8	76.61	HZ	256	9	64.00	HZ	256
10	53.82	HZ	128	9	64.00	HZ	256
10	53.82	HZ	128	11	45.25	HZ	128
12	38.06	HZ	128	11	45.25	HZ	128
12	38.06	HZ	128	13	32.00	HZ	64
14	26.91	HZ	64	13	32.00	HZ	64
14	26.91	HZ	64	15	22.63	HZ	64
16	19.25	HZ	64	15	22.63	HZ	64
16	19.25	HZ	64	17	16.00	HZ	64
18	13.45	HZ	64	17	16.00	HZ	64
18	13.45	HZ	64	19	11.31	HZ	64
20	9.51	HZ	32	19	11.31	HZ	64
20	9.51	HZ	32	21	8.00	HZ	32
22	6.73	HZ	32	21	8.00	HZ	32
22	6.73	HZ	32	23	5.66	HZ	32
24	4.76	HZ	32	23	5.66	HZ	32
24	4.76	HZ	32	25	4.00	HZ	32

Sequence number	Frequency/period	Unit	Multiplicity
Sequence number	Frequency/period	Unit	Multiplicity	26	3.36	HZ	32
27	2.83	HZ	16	26	3.36	HZ	32
27	2.83	HZ	16	28	2.38	HZ	16
29	2.00	HZ	16	28	2.38	HZ	16
29	2.00	HZ	16	30	1.68	HZ	16
31	1.41	HZ	16	30	1.68	HZ	16
31	1.41	HZ	16	32	1.19	HZ	16
33	1.00	HZ	16	32	1.19	HZ	16
33	1.00	HZ	16	34	1.19	Second	16
35	1.41	Second	16	34	1.19	Second	16
35	1.41	Second	16	36	1.68	Second	16
37	2.00	Second	16	36	1.68	Second	16
37	2.00	Second	16	38	2.38	Second	16
39	2.83	Second	8	38	2.38	Second	16
39	2.83	Second	8	40	3.36	Second	8
41	4.00	Second	8	40	3.36	Second	8
41	4.00	Second	8	42	4.76	Second	8
43	5.66	Second	8	42	4.76	Second	8
43	5.66	Second	8	44	6.73	Second	8
45	8.00	Second	8	44	6.73	Second	8
45	8.00	Second	8	46	9.52	Second	6
47	11.31	Second	6	46	9.52	Second	6
47	11.31	Second	6	48	13.45	Second	6
49	16.00	Second	6	48	13.45	Second	6
49	16.00	Second	6	50	19.03	Second	6

Sequence number	Frequency/period	Unit	Multiplicity
Sequence number	Frequency/period	Unit	Multiplicity	51	22.63	Second	4
52	26.91	Second	4	51	22.63	Second	4
52	26.91	Second	4	53	32.00	Second	4
54	38.06	Second	4	53	32.00	Second	4
54	38.06	Second	4	55	45.26	Second	4
56	53.81	Second	4	55	45.26	Second	4
56	53.81	Second	4	57	64.00	Second	4
58	76.13	Second	4	57	64.00	Second	4
58	76.13	Second	4	59	90.52	Second	4
60	107.63	Second	3	59	90.52	Second	4
60	107.63	Second	3	61	128.00	Second	3
62	152.26	Second	3	61	128.00	Second	3
62	152.26	Second	3	63	181.03	Second	3
64	215.25	Second	3	63	181.03	Second	3
64	215.25	Second	3	65	256.00	Second	3
66	304.51	Second	3	65	256.00	Second	3
66	304.51	Second	3	67	362.06	Second	3
68	430.51	Second	3	67	362.06	Second	3
68	430.51	Second	3	69	512.00	Second	3
70	609.03	Second	3	69	512.00	Second	3
70	609.03	Second	3	71	724.12	Second	3
72	861.01	Second	3	71	724.12	Second	3
72	861.01	Second	3	73	1024.00	Second	3

Claims

1, a kind of artificial source's temporal frequency electromagnetic sounding method, it is characterized in that: adopt long lead galvanic couple source or big loop line magnetic couple source excitation and a plurality of survey station to arrange the receive mode image data, each survey station is made up of electric acquisition station and magnetic acquisition station, comprise two levels and a vertical magnetic field (Hx, Hy and Hz), two horizontal component of electric fields (Ex and Ey), mode of excitation adopts zero passage or non-zero passage square wave, excites from the high frequency to the low frequency and continuous;

Described transmit square waves highest frequency is 256HZ, and low frequency is 1024 seconds, and the multiplicity of high frequency is many, the low repetition of low frequency, each frequency of high band repeats to excite 1024 times, each frequency of low-frequency range repeats to excite 3 times, between strengthen gradually;

Described zero passage or non-zero passage square wave comprise: excitation waveform is dutycycle 1: 1: 1: 1 or 2: 1: 2: 1 or 3: 1: 3: 1 or 1: 1 positive and negative square wave;

The described survey station spacing quantity of hour magnetic acquisition station can reduce, and several survey stations are laid a three-component magnetic acquisition station;

Described square-wave signal receives all signals that each frequency repeats to excite by GPS synchronously with emission;

Adopt conventional method to described vertical magnetic field (Hx, Hy and Hz), the signal of each field component of two horizontal component of electric fields (Ex and Ey) superposes, signal to each frequency record carries out spectrum analysis, obtain the fundamental frequency and the harmonic wave thereof of each frequency signal, frequency is carried out above-mentioned processing one by one, the frequency spectrum that gathers all signals then obtains the frequency spectrum of each field component from the high frequency to the low frequency signal, by the underground rerum natura model of the inverting reconstruct of these field component information;

Described underground rerum natura model comprises the resistivity section that reflects underground electric conductivity, reflects the polarizability section of underground electric polarizability and the electrical interface of reflection subsurface resistivity sudden change;

Described underground rerum natura model comprises the resistivity section that reflects underground electric conductivity, reflects the polarizability section of underground electric polarizability and the electrical interface of reflection subsurface resistivity sudden change.