CN109838229A - A kind of electromagnetic resistivity data processing method - Google Patents

Abstract

The invention discloses an electromagnetic wave resistivity data processing method for formation resistivity evaluation, which is different from the conventional electromagnetic wave resistivity using two receiving antennas. Measurement data processing method. In this method, numerical simulation is used to calculate the receiving antenna electromotive force of a certain coil distance and working frequency under different formation resistivity (conductivity) environments, and compare it with the receiving antenna electromotive force value under the condition of infinite resistivity to obtain the amplitude ratio and resistivity conversion. relation. Before the instrument works, firstly perform air calibration on the receiving antenna under the condition of full temperature (20 ^o C~150 ^o C). The value is used as the amplitude ratio, and then the formation resistivity (conductivity) value is obtained by interpolation through the conversion relationship between the amplitude ratio and the resistivity. The invention is suitable for the field of logging while drilling in oil and gas exploration.

Description

A kind of electromagnetic wave resistivity data processing method

Technical field:

The invention relates to the field of measurement-while-drilling or logging-while-drilling data processing methods for oil and natural gas drilling operations, and is particularly suitable for a data processing method for providing formation electromagnetic wave resistivity in a geosteering measurement-while-drilling system.

Background technique:

In the process of oilfield exploration and development, formation geological information and engineering parameters need to be measured. The required parameters often include formation environment parameters, downhole drilling tool position, orientation, and drilling environment parameters. At present, there are many conventional LWD tools that can provide the above parameters. As an important instrument for evaluating formation properties, electromagnetic wave resistivity instrument can provide formation resistivity information to evaluate the oil-bearing property of the formation. At present, commercial electromagnetic wave resistivity instruments often include two or more receiving antennas, and the formation resistivity information is obtained by converting the amplitude ratio or phase difference of the receiving antennas. The processing method of this type of instrument determines that these conventional electromagnetic wave resistivity instruments often have a measurement zero length of 10-15m, which cannot reflect the formation resistivity at the drill bit in time, especially for thin oil layers. Therefore, the closer the resistivity measurement device is to the drill bit, the better. , but the proximity to the drill bit has certain restrictions on the size of the instrument. In some cases, the fewer the number of antennas, the better to meet the space requirements.

At present, Schlumberger, Halliburton, Baker Hughes and other international petroleum engineering service companies have successively announced their own patented technologies in multi-component, multi-antenna distance, multi-frequency instruments (such as US Patent Publication No. 6777940, No. .7038455, No.7557580, No.6181138, No.20050140373, No.7375530, No.7483793, etc.) have been widely used in formation evaluation and geosteering and achieved good results.

In recent years, the design and manufacture of azimuth-while-drilling electromagnetic wave instruments has developed rapidly in China, and a series of electromagnetic wave resistivity measurement methods and devices have also been proposed, such as an electromagnetic wave resistivity logging while drilling tool (201410773943.8), a A measuring device and method for measuring resistivity while drilling (201310698427.9) The basic principle is based on dual receiving antennas, measuring the amplitude ratio and phase difference of the two receiving antennas to convert the formation resistivity.

Invention content:

The purpose of the present invention is to solve the problems existing in the prior art, and to propose an electromagnetic wave resistance which can not only meet the space requirements of the near-bit instrument design, but also can improve the measurement redundancy of the conventional electromagnetic wave resistivity instrument while drilling, and improve the measurement reliability. rate data processing method.

An electromagnetic wave resistivity data processing method, the method is based on an electromagnetic wave resistivity measuring instrument while drilling, and the measuring unit of the electromagnetic wave resistivity measuring instrument while drilling is only composed of a transmitting antenna and a receiving antenna, and is not coupled on the transmitting antenna. ;in:

Simulate the receiving antenna electromotive force under the environment of different formation conductivity at a certain antenna distance and working frequency, and compare the receiving antenna electromotive force value under the condition of infinite resistivity to obtain the conversion relationship between the amplitude ratio and the resistivity;

Use at least one amplitude ratio in a specific resistivity environment to perform conversion relationship correction;

Under the condition of full temperature, the electromotive force of the receiving antenna is scaled, and the value of the electromotive force measured by the receiving antenna of the instrument is compared with the electromotive force value in the air at the corresponding temperature, and then the formation resistivity value is obtained by conversion.

The processing method in the above scheme includes the conversion of the full temperature air scale and the measured data:

Step 1, simulate and calculate the full temperature air scale at a certain coil distance and working frequency, that is, the temperature is in the range of 20°C to 150°C, and use the electromagnetic wave resistivity measuring instrument while drilling to measure the electromotive force of the receiving antenna under air conditions. Record an electromotive force data every two degrees of change;

Step 2: Use a polynomial to fit the relationship between the temperature and the air scale electromotive force, and obtain the fitting polynomial coefficient. The fitting polynomial coefficient is stored in the calibration file based on the electromagnetic wave resistivity measuring instrument while drilling, and the full temperature is obtained through the fitted polynomial. Free-etched electromotive force at any temperature within the range;

Step 3, simulate the electromotive force of the receiving antenna under the condition of different medium resistivity 0.1Ω·m～1000Ω·m, and compare the electromotive force under the condition of infinite resistivity to obtain the conversion relationship curve of resistivity and amplitude ratio,

The theoretical value of the electromotive force under the condition of infinite resistivity is:

Where: i is a complex unit, ω=2πf, f is the operating frequency of the instrument, μ is the magnetic permeability of the air medium, s _R is the magnetic flux area of the receiving antenna, _NR is the number of turns of the receiving antenna, M is the magnetic moment of the receiving antenna, L is the antenna distance,

in: σ is the formation conductivity, e is a natural constant,

Comparing the electromotive force of the receiving antenna under different resistivities calculated by formula (6) with the electromotive force value of the infinite resistivity calculated by formula (5), the resistivity conversion curve when one receiving antenna is used is obtained;

Step 4. Select the emission frequency of the electromagnetic wave resistivity measuring instrument while drilling to be 100 kHz to 4 MHz to emit electromagnetic waves;

Step 5: Measure and record the amplitude and temperature of the receiving antenna electromotive force signal;

Step 6, the receiving antenna electromotive force signal is compared with the air scale electromotive force under the temperature condition, and the amplitude ratio is obtained;

Step 7: Interpolate the obtained amplitude ratio with the resistivity conversion curve obtained in step 3 to obtain the formation resistivity.

Further, the specific conversion formula in step 2 is:

Among them: A _amp is the calculated amplitude ratio; abs is the absolute value, which means to obtain the electromotive force amplitude, V _R1 and V _R1air are the measured electromotive force of the receiving antenna and the receiving antenna under the air scale condition of 20℃～150℃, respectively The electromotive force, that is to measure the electromotive force in the air environment of the receiving antenna in the full temperature range, and fit the relationship between the temperature and the airborne electromotive force, using polynomial fitting, the fitting formula is shown in equation (4):

V(T)=a ₄ T ^(-2) +a ₃ T ^(-1) +a ₂ T ⁽¹⁾ +a ₁ T ⁽²⁾ +a ₀ T ⁽⁰⁾ (4)

Among them: T is the temperature of the measurement point, V is the instantaneous receiving antenna electromotive force calculated at the temperature of the measurement point, a ₀ , a ₁ , a ₂ , a ₃ , a ₄ are the polynomials obtained by least squares fitting coefficient.

Further, the coil distance between the transmitting antenna and the receiving antenna ranges from 8 in to 40 in.

Further, in the process of simulation calculation, the transmitting antenna and the receiving antenna are approximated as magnetic dipoles, and the electromotive force of the receiving antenna is calculated under the condition of infinite uniform stratum.

Further, the formation resistivity greater than 1000Ω·m is considered as infinite formation resistivity, and the simulated value of electromotive force under different resistivity conditions is compared with the response value of infinite formation resistivity, forming the formation resistivity-amplitude ratio response. Correspondence.

The electromagnetic wave resistivity data processing method used for formation resistivity evaluation of the present invention is different from the conventional electromagnetic wave resistivity that adopts two receiving antennas. This method is the electromagnetic wave resistivity data processing method under the condition that only one antenna is used as the receiving antenna. Numerical simulation Calculate the receiving antenna electromotive force under different formation resistivity (conductivity) environments at a certain antenna distance and operating frequency, and compare the receiving antenna electromotive force value under the condition of infinite resistivity to obtain the conversion relationship between the amplitude ratio and the resistivity, using at least one to determine The amplitude ratio in the resistivity environment is corrected for the conversion relationship. Before the instrument works, the receiver antenna is firstly calibrated in air under full temperature conditions, and the relationship between temperature and air-scale electromotive force is obtained by fitting. In the actual measurement process, the value of the electromotive force measured by the receiving antenna of the instrument is compared with the electromotive force value in the air at the corresponding measurement temperature, and then the formation resistivity value is obtained by interpolation through the conversion relationship between the amplitude ratio and the resistivity, which is a good solution. The existing electromagnetic wave resistivity adopts two receiving antennas to limit the size of the instrument, which can not only meet the space requirements of the near-bit instrument design, but also improve the measurement redundancy of the conventional electromagnetic wave resistivity instrument while drilling, and improve the measurement reliability.

Description of drawings:

The present invention will be further described below with reference to the accompanying drawings.

Figure 1 is a schematic diagram of the measurement principle of conventional electromagnetic wave resistivity single-transmitting and double-receiving;

Fig. 2 is the conventional electromagnetic wave resistivity amplitude resistivity and phase resistivity conversion curve;

FIG. 3 is a schematic diagram of the measurement principle of single sending and single receiving in an embodiment of the present invention;

Fig. 4 is the relationship between formation resistivity and amplitude ratio in an embodiment of the present invention;

5 is a process flow of formation resistivity measurement data processing in an embodiment of the present invention;

FIG. 6 is a simulation of formation model response in an embodiment of the present invention.

Detailed ways:

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

The most basic instrument measurement unit in the electromagnetic wave propagation resistivity logging instrument while drilling adopted in the method of the invention is a transmitting antenna and a receiving antenna, and the electromagnetic wave propagation resistivity logging instrument while drilling measures the phase change of electromagnetic wave propagation in the formation and amplitude decay. When electromagnetic waves propagate in a homogeneous medium, amplitude attenuation and phase shift will occur. For strata with different resistivities, the amplitude attenuation and phase changes of electromagnetic waves are different. Therefore, the electromagnetic wave resistivity measurement while drilling inverts the physical parameters of the formation according to the changes in the amplitude and phase of the induced electromotive force of the receiving antenna when the electromagnetic wave passes through different physical formations (conductivity, permeability, permittivity). The model is an infinite uniform stratum model.

The conventional electromagnetic wave resistivity measurement unit while drilling is single-transmitting and dual-receiving, and its measurement principle is shown in Figure 1, where 101 is the transmitting antenna, and 102 and 103 are the receiving antennas respectively. 104 and 105 are the electromagnetic waves detected by the receiving antennas 102 and 103, respectively. The formulas for calculating the amplitude ratio and phase difference measured by the two receiving antennas are:

P _pha = arg(V _R1 )-arg(V _R2 ) (2)

Among them: A _amp and P _pha are the calculated amplitude ratio and phase difference, arg represents the phase angle, _VR1 and _VR2 are the induced electromotive force of the two receiving antennas respectively, abs represents the magnitude of the induced electromotive force, and its amplitude ratio, The conversion relationship between phase difference and resistivity.

As shown in Figure 2, the amplitude resistivity and the phase resistivity can be obtained by using the conversion relationship between the amplitude ratio and the phase difference. Among them, 201 is the conversion curve of amplitude resistivity under the working frequency of 2MHz; 202 is the conversion curve of amplitude resistivity under the working frequency of 400kHz; 203 is the conversion curve of phase resistivity under the working frequency of 2MHz; 204 is the conversion curve of phase resistivity under the working frequency of 400kHz conversion curve. This resistivity conversion method must have at least two receiving antennas or use antenna multiplexing technology, that is, coupling is performed on the transmitting antenna, and the amplitude ratio and phase difference between the transmitting and receiving antennas are calculated.

The data processing method proposed by the present invention can obtain the amplitude resistivity of the formation by using a receiving antenna without coupling measurement on the transmitting antenna. The schematic diagram of the measurement principle is shown in Figure 3, where 301 is the transmitting antenna, 302 is the receiving antenna, 303 is the electromagnetic wave measured by the receiving antenna in the air environment, and 304 is the electromagnetic wave measured in the stratum environment.

The specific conversion formula is:

Among them: A _amp is the calculated amplitude ratio, V _R1 , V _R1air are the measured electromotive force of the receiving antenna 302 (R1) and the air scale of the receiving antenna 302 (R1) at full temperature (20℃～150℃) (referred to as empty engraving). ) under the condition of the electromotive force (the free-time electromotive force is the free-time value at the measured temperature). Since the receiving antenna measures the electromotive force amplitude using an RMS circuit, the receiving antenna electromotive force amplitude is greatly affected by temperature, and temperature calibration must be carried out when this method is used. That is to measure the electromotive force in the air environment of the receiving antenna in the full temperature range and fit the relationship between the temperature and the empty engraved electromotive force, using polynomial fitting, the fitting formula is shown in equation (4):

V(T)=a ₄ T ^(-2) +a ₃ T ^(-1) +a ₂ T ⁽¹⁾ +a ₁ T ⁽²⁾ +a ₀ T ⁽⁰⁾ (4)

Among them: T is the temperature of the measurement point, V is the instantaneous receiving antenna electromotive force calculated at the temperature of the measurement point, a ₀ , a ₁ , a ₂ , a ₃ , a ₄ are the polynomials obtained by least squares fitting coefficient. The order of the polynomial can be adjusted according to temperature experiments and fitting errors. The free-running electromotive force at any working temperature can be calculated by formula (4), ensuring that the free-running electromotive force value at the same temperature as the measurement point is used for the calculation of the amplitude ratio. The measured value of the electromotive force in the RMS circuit has an approximately linear relationship with the actual value at the same temperature. , the temperature effect can be largely eliminated by this temperature scale.

4 is an amplitude resistivity conversion curve according to an embodiment of the present invention, wherein 401 is the amplitude resistivity conversion curve when the antenna distance is 24in under the operating frequency of 2MHz; 402 is the amplitude resistivity conversion curve when the antenna distance is 12in under the 2MHz operating frequency; 403 is the amplitude resistivity conversion curve when the antenna distance is 24in at 400kHz working frequency; 404 is the amplitude resistivity conversion curve when the antenna distance is 24in at 400kHz working frequency. It can be seen from the conversion curve that the resistivity conversion method is similar to the resistivity conversion curve of the conventional dual-receiving antenna. In the actual resistivity conversion process, the conversion curve can be converted into a two-dimensional table, and the formation resistivity (conductivity) can be obtained through real-time interpolation query. ). From the conversion curves in Figure 2 and Figure 4, it can be seen that the conversion results of the two methods have good contrast.

FIG. 5 is a specific embodiment of the processing flow of formation resistivity measurement data in the electromagnetic wave resistivity data processing method of the present invention. The data processing process includes full temperature air calibration and conversion of measured data. in:

Step 501 is full temperature (20°C-150°C) air calibration, measuring the electromotive force of the receiving antenna under air conditions, and recording an electromotive force data every two degrees during the air calibration process.

Step 502 is to use a polynomial to fit the relationship between the temperature and the air scale electromotive force, to obtain the fitted polynomial coefficient, and the obtained polynomial coefficient is stored in the instrument scale file. Through the fitted polynomial, the free-etching electromotive force at any temperature in the whole temperature range can be obtained.

Step 503 is to simulate the electromotive force of the receiving antenna under different resistivity conditions, and compare the electromotive force under the condition of infinite resistivity to obtain a resistivity-amplitude ratio conversion curve.

The theoretical value of the electromotive force under the condition of infinite resistivity is:

Where: i is a complex unit, ω=2πf, f is the operating frequency of the instrument, μ is the magnetic permeability of the air medium, s _R is the magnetic flux area of the receiving antenna, _NR is the number of turns of the receiving antenna, M is the magnetic moment of the receiving antenna, L is the antenna distance.

in: σ is the formation conductivity, and e is a natural constant.

Comparing the electromotive force of the receiving antenna under different resistivities calculated by formula (6) with the electromotive force value of the infinite resistivity calculated by formula (5), the resistivity conversion curve when one receiving antenna is used can be obtained.

Step 504 selects the transmitting frequency of the instrument (100kHz～4MHz), and transmits electromagnetic waves.

Step 505 is to measure and record the amplitude and temperature of the receiving antenna electromotive force signal.

Step 506 is to compare the received antenna electromotive force signal with the air scale electromotive force under the temperature condition to obtain an amplitude ratio.

Step 507 is to interpolate the obtained amplitude ratio with the conversion curve obtained in step 503 to obtain formation resistivity.

FIG. 6 is a simulation result of the response to the same formation using the single-transmitting-dual-receiving measurement mode and data processing method and the single-transmitting-single-receiving measurement mode and data processing method in the embodiment of the present invention. The simulated formation model is a three-layer formation, and the formation resistivity is 1Ω·m, 20Ω·m and 1Ω·m, respectively. 601 is the amplitude resistivity response curve under the single-transmit and double-receive measurement mode when the working frequency is 2MHz; 602 is the amplitude resistivity response curve under the single-transmit and single-receive measurement mode when the working frequency is 2MHz; 603 is the working frequency When it is 400kHz, the amplitude resistivity response curve under the condition of single-transmitting and double-receiving measurement mode; 604 is the amplitude resistivity response curve under the condition of single-transmitting and single-receiving measurement mode when the operating frequency is 400kHz. From the response simulation curve, it can be seen that the resistivity curve obtained by the patented method has a good similarity with the resistivity curve obtained by the single-transmit and double-receive measurement mode and data processing method under different operating frequency conditions, which also verifies. Feasibility and accuracy of the method.

Claims (6)

1. a kind of electromagnetic resistivity data processing method, this method is based on boring electromagnetic resistivity measuring instrument, and should be with The measuring unit for boring electromagnetic resistivity measuring instrument is only a transmitting antenna and a receiving antenna composition, is not also being emitted It is coupled on antenna；It is characterized by:

Receiving antenna electromotive force when simulation calculates certain day line-spacing and working frequency under Different Strata conductivity environments, and with electricity Receiving antenna electromotive force value under the conditions of resistance rate is infinitely great, which is compared, obtains Amplitude Ratio and resistivity transformational relation；

Determine that the Amplitude Ratio under resistivity environment carries out transformational relation correction using at least one；

Under the conditions of total temperature carry out receiving antenna electromotive force scale, the value for the electromotive force that instrument receiving antenna measurement is obtained with it is right Electromotive force value in air at a temperature of answering makees Amplitude Ratio, then by being converted to formation resistivity values.

2. requiring the electromagnetic resistivity data processing method according to right 1, it is characterised in that processing method includes full temperature Spend the conversion of air scale and measured data:

Step 1, total temperature air scale when simulation calculates certain coil spacing and working frequency, i.e., temperature is in 20 DEG C~150 DEG C models It encloses, using the electromotive force with receiving antenna under brill electromagnetic resistivity measuring instrument measurement air conditions, in air scale process The middle every two degrees of temperature change record an electromotive force data；

Step 2 obtains fitted polynomial coefficients, is fitted using the relationship of fitting of a polynomial temperature and air scale electromotive force To multinomial coefficient be stored in based on bore electromagnetic resistivity measuring instrument calibration file in, pass through the multinomial of the fitting Obtain the empty quarter electromotive force within the scope of total temperature under the conditions of arbitrary temp；

Step 3 simulates receiving antenna electromotive force under the conditions of 0.1 Ω of Ω m~1000 m of different medium resistivity, with infinity Electromotive force is compared under resistivity conditions, obtains resistivity and Amplitude Ratio transformational relation curve,

Electromotive force theoretical value under the conditions of resistivity is infinitely great are as follows:

Wherein: i is complex unit, and the π of ω=2 f, f are instrument working frequency, and μ is air dielectric magnetic conductivity, s_RFor receiving antenna magnetic Logical area, N_RFor receiving antenna the number of turns, M is receiving antenna magnetic moment, and L is day line-spacing,

Wherein:σ is formation conductivity, and e is natural constant,

By the receiving antenna electromotive force and formula (5) resistivity for being calculated in the case of different resistivity that formula (6) is calculated Electromotive force value when infinitely great compares resistivity transformation curve when obtaining using a receiving antenna；

Step 4: selection emits electromagnetic wave with electromagnetic resistivity measuring instrument tranmitting frequency 100kHz~4MHz is bored；

Step 5, measurement and record receiving antenna electromotive force signal amplitude and temperature；

Step 6, receiving antenna electromotive force signal obtain Amplitude Ratio compared with air scale electromotive force under the conditions of the temperature；

Step 7 obtains formation resistivity to the resistivity transformation curve interpolation that obtained Amplitude Ratio and step 3 obtain.

3. requiring the electromagnetic resistivity data processing method according to right 2, it is characterised in that specific turn in step 2 Change formula are as follows:

Wherein: A_ampFor the Amplitude Ratio being calculated；Abs is to take absolute value, and electromotive force amplitude, V are sought in expression_R1、V_R1airRespectively Electromotive force of the measurement electromotive force and receiving antenna of receiving antenna under the conditions of 20 DEG C~150 DEG C of air scales of temperature, i.e., complete Temperature and the empty relationship for carving electromotive force are measured and be fitted in temperature range to electromotive force under receiving antenna air environment, is used Fitting of a polynomial, shown in fitting formula such as formula (4):

V (T)=a₄T^(-2)+a₃T^(-1)+a₂T⁽¹⁾+a₁T⁽²⁾+a₀T⁽⁰⁾ (4)

Wherein: T is measurement point temperature, and V is the empty quarter receiving antenna electromotive force being calculated at a temperature of the measurement point, a₀、a₁、 a₂、a₃、a₄For the multinomial coefficient being fitted by least square method.

4. requiring the electromagnetic resistivity data processing method according to right 2 or 3, it is characterised in that: transmitting antenna with connect The coil spacing range for receiving antenna is 8in~40in.

5. requiring the electromagnetic resistivity data processing method according to right 2 or 3, it is characterised in that: calculated in simulation By transmitting antenna and receiving antenna it is approximately magnetic dipole in journey, and calculates its receiving antenna under the conditions of infinitely great uniformly stratum Electromotive force.

6. requiring the electromagnetic resistivity data processing method according to right 5, it is characterised in that: formation resistivity to be greater than 1000 Ω m think infinitely great formation resistivity, and by under the conditions of different resistivity the electromotive force analogue value and infinitely great stratum Resistivity response value is compared, and the corresponding relationship of formation resistivity and Amplitude Ratio response is formed.