CN105525918B - Dual lateral logging instrument, electrode system thereof and formation resistivity measuring method - Google Patents

Abstract

The invention relates to a double lateral logging tool, an electrode system and a method for measuring formation resistivity. The electrode system includes an electrode system and an insulating mandrel, which is composed of a plurality of electrodes arranged on one insulating mandrel, and is passed through the insulating mandrel. The wire is connected to the measurement circuit, and the electrodes are separated by insulating materials. The center of the insulating mandrel is a metal rod. The center of the metal rod is provided with a through hole. The metal rod is insulated from the electrode system. The system includes: main electrodes A0, A0' arranged in the middle of the electrode system; at least one pair of shield electrodes A2, A2' and A1, A1' for emitting shield current to focus the main current; multiple pairs of voltage measurements for measuring electrode voltage Electrodes A1*, A1*' and M0, M0'; and at least one pair of voltage monitoring electrodes M2, M2' and M1, M1' for voltage monitoring, wherein shield electrodes A2, A2' are short-circuited, and main electrodes A0, A0 'Short-circuit, other electrodes are not short-circuited. As a result, higher measurement accuracy is achieved than with the hard focus method.

Description

Double lateral logging tool and its electrode system, formation resistivity measurement method

technical field

The invention relates to a logging device for petroleum exploration and development, in particular to a dual lateral logging tool, an electrode system and a method for measuring formation resistivity.

Background technique

The dual lateral logging tool is the main tool for measuring formation resistivity in open-hole wells, studying formation invasion changes, and estimating oil saturation. The traditional dual lateral logging tool mainly includes electrode system, electronic circuit, insulation sub joint, the total length is about 7 to 10 meters, the deep lateral detection depth is about 1 to 1.5 meters, and the shallow lateral detection depth is about 0.2 to 0.5 meters. The resolution is about 0.6 meters. When the traditional dual lateral logging tool performs deep lateral logging, the annular electrode emits current into the formation, and the columnar electrode emits shielding current to focus on the main current. Equipotential. For example, Chinese patent CN1712995A discloses a strong focusing double lateral logging tool, the structure of which mainly includes an insulating subsection, an electrode system and an electronic circuit part, wherein the electrode system includes a main electrode, and the main electrode is composed of a main electrode. The instrument is composed of the supervising electrode, the shielding electrode, the auxiliary supervising electrode and the return electrode which are symmetrical with each other. Shielded deep sideways strong focus mode. In theory, this way of focusing requires the amplifier to have infinite gain, but in practice, since the gain of the amplifier is finite, the supervisory electrodes are not strictly equipotential and introduce errors in the measurement results. This error is small in conventional dual-lateral logging, but can be large in high-resolution dual-lateral logging.

With the deepening of oil and gas exploration and development, thin interbeds and other reservoirs have gradually become the focus of exploration, which requires high-resolution logging tools, while the resolution of traditional dual lateral logging tools is generally 0.6m. It cannot meet the needs of exploration. At the same time, the length of the rat hole in the logging operation is short, and the operation volume of complex wellbore conditions such as highly deviated wells, horizontal wells, and fishbone lateral wells is increasing year by year. The length of traditional dual lateral logging tools is about 7-10m, which is not conducive to well site construction operations and combined logging, and greatly increases the probability of sticking in complex wellbore conditions such as highly deviated wells, horizontal wells, and fishbone lateral wells.

Patent application No. 201210233337 filed by the 22nd Research Institute of China Electronics Technology Group Corporation discloses a high-resolution azimuthal resistivity lateral logging tool and a logging method. The high-resolution azimuthal resistivity lateral logging The instrument is mainly composed of an azimuth electrode system and a measuring electronic circuit. The electrode system is composed of a plurality of lateral electrode rings of different widths embedded on an insulating carrier and an azimuth electrode ring M0. The center of the electrode system is M0, 14 different widths. The electrode rings with the same name take M0 as the axis of symmetry and are arranged at different intervals. Each electrode ring with the same name is short-circuited with a wire to maintain the equipotential. . Although the high-resolution azimuthal resistivity logging tool and logging method adopts digital focusing mode and hard focusing mode, compared with the original hard focusing circuit, the collection quantity is increased, the measurement accuracy is greatly improved, and the measurement information is also richer, but due to the use of various The electrode ring of the same name is short-circuited with wires, which still does not solve the influence of the vertical potential gradient formed in the center of the instrument, so it is difficult to achieve higher measurement accuracy.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a high-resolution dual lateral logging tool, an electrode system of the dual lateral logging tool, and a resistivity measurement method based on a software focusing method for the above-mentioned defects in the prior art. .

In order to solve the above-mentioned problems in the prior art, the present invention provides a double lateral logging tool electrode system, including an electrode system and an insulating mandrel, the electrode system is composed of a plurality of electrodes arranged on one of the insulating mandrels The electrodes are formed and connected to the measurement circuit by wires, where

The plurality of electrodes are separated by insulating materials, the center of the insulating core rod is a metal rod, the center of the metal rod is provided with a through hole, and the metal rod is insulated from the electrode system, so the The electrode system includes:

main electrodes A0, A0' arranged in the middle of the electrode system;

at least one pair of shield electrodes A2, A2' and A1, A1' that emit a shield current to focus the main current;

Pairs of voltage measuring electrodes A1*, A1*' and M0, M0' for measuring electrode voltage; and

at least one pair of voltage monitoring electrodes M2, M2' and M1, M1' for voltage monitoring,

The shielding electrodes A2 and A2' are short-circuited, the main electrodes A0 and A0' are short-circuited, and the other electrodes are not short-circuited.

Preferably, in the electrode system of the dual lateral logging tool, a pair of electrodes M0, M0' among the plurality of pairs of voltage measuring electrodes are located in the middle of the electrode system, and are used to measure the voltage of the main electrodes A0, A0' respectively. Voltage.

Preferably, in the electrode system of the dual lateral logging tool, the plurality of electrodes are sequentially arranged from one end to the other end of the electrode system as electrode A2, electrode A1*, electrode A1, electrode M2, electrode M1, electrode A0, Electrode M0, Electrode M0', Electrode A0', Electrode M1', Electrode M2', Electrode A1', Electrode A1*', Electrode A2'.

The present invention also provides a dual lateral logging tool for measuring formation resistivity, which has the above-mentioned dual lateral logging tool electrode system.

In addition, the present invention also provides a method for measuring formation resistivity, which adopts the above-mentioned dual lateral logging tool to measure formation resistivity, and is characterized in that the above-mentioned two-way logging tool is operated in the following three modes:

、

、

、

，同时记录电极N的电位，记为

；In mode 1, the current output by the output module is loaded on the electrodes A1, A1' and A2, A2', the auxiliary supervision circuit module keeps the electrodes A1* and A2 at the same potential, and the data acquisition module records the electrodes M2, A2 and A2 in this mode. The potentials of M2' and electrodes M1 and M1' are denoted as

,

,

,

, while recording the potential of electrode N, denoted as

;

、

、

、

，同时记录电极N电位，记为

；In mode 2, the current output by the output module is loaded on the electrodes A1, A1', and returns to the electrodes A2, A2', the data acquisition module records the potentials of the electrodes M2, M2', and the electrodes M1, M1' in this mode, and denoted as

,

,

,

, while recording the electrode N potential, denoted as

;

、

、

、

、

、

，同时记录电极N电位，记为

；记录电极A0、A0’上的电流，记为

、

。In mode 3, the current output by the output module is loaded on electrodes A0, A0', and returns to electrodes A1, A1' and A2, A2', the supervisory circuit module keeps electrodes A1* and A2 equipotential, and electrodes A1* 'Equipotential with electrode A2', the data acquisition module records the potentials of electrodes M2, M2', electrodes M1, M1', electrodes M0, M0' in this mode, and recorded as

,

,

,

,

,

, while recording the electrode N potential, denoted as

; The current on the recording electrodes A0 and A0', denoted as

,

.

Preferably, in the above-mentioned formation resistivity measurement method, the deep lateral apparent resistivity can be obtained by using the combination of the mode 1 and the mode 3:

为深侧向仪器系数，in,

is the deep lateral instrument coefficient,

。

.

Preferably, in the above-mentioned formation resistivity measurement method, using the combination of the mode 2 and the mode 3, the shallow lateral apparent resistivity can be obtained:

为浅侧向仪器系数，in,

is the shallow lateral instrument coefficient,

。

.

Preferably, in the above-mentioned formation resistivity measurement method, the following high-resolution deep and shallow lateral apparent resistivity curves can be obtained by using the data collected in the three working modes:

、

分别为高分辨率深、浅侧向仪器系数，in,

,

are the high-resolution deep and shallow lateral instrument coefficients, respectively,

。

.

Compared with the prior art, the present invention has the following advantages:

The invention solves the problems such as the traditional double-sided hardware focusing method, the circuit realizes the main monitoring control through a closed loop, is greatly affected by the peripheral environment, and the focusing effect is deviated, avoids the influence of the residual potential between the monitoring electrodes in the hard focusing, and greatly improves the vertical resolution. At the same time, the vertical gradient formed by the center of the instrument is solved, which further enhances the focusing ability of the instrument and improves the measurement accuracy of the instrument.

In addition, the present invention can simultaneously obtain two standard deep and shallow resistivity curves and two high-resolution deep and shallow resistivity curves; the high-resolution logging curve can identify a thin layer of 0.1 m, and can measure a thin layer of 0.4 m. The true resistivity of the layer.

Furthermore, the design scheme of the electrode system of the high-resolution dual lateral logging tool of the present invention can effectively shorten the length of the tool and improve the applicability of the tool in a complex wellbore environment.

Description of drawings

FIG. 1 is a schematic structural diagram of the electrode system of the high-resolution dual lateral logging tool of the present invention.

Fig. 2A and Fig. 2B are respectively Mode 1 and Mode 3 of the high-resolution dual-lateral logging tool of the present invention; Fig. 2C is a deep lateral logging synthesized by using the high-resolution dual-lateral logging tool of the present invention model.

Fig. 3A and Fig. 3B are respectively Mode 2 and Mode 3 of the high-resolution dual-lateral logging tool of the present invention; Fig. 3C is the shallow lateral logging synthesized by using the high-resolution dual-lateral logging tool of the present invention model.

Detailed ways

The traditional dual lateral logging tool adopts the hardware focusing method, and the circuit realizes the main monitoring control through a closed loop, which is greatly affected by the external environment (temperature changes, power supply fluctuations, etc.) The magnification reaches 25,000 times, which is close to the limit of circuit design). The present invention adopts the software focusing method. Software focusing is a brand-new focusing method. It uses the principle of electric field superposition to synthesize the focusing current from the currents in two non-focusing states. The focusing conditions are unconditionally satisfied, so it can prevent the influence of the residual current between the monitoring electrodes during the hardware focusing process. Thus, it becomes an effective method to improve the vertical resolution.

The structure of the electrode system of the high-resolution dual lateral logging tool of the present invention is shown in Figure 1. It is mainly composed of two parts: an electrode system and an insulating mandrel. The electrode system is connected with the measurement circuit through wires. The whole system also includes There are reference electrode N (not shown) and return electrode B. In addition, the electrode system is composed of 14 electrodes arranged on an insulating mandrel. From one end of the electrode system to the other end, the electrode names are A2, A1*, A1, M2, M1, A0, M0, M0', A0. ', M1', M2', A1', A1*', A2', and are connected in series on an insulating mandrel, the electrodes are separated by insulating materials, and the center of the insulating mandrel is a metal rod, There is a through hole in the center of the metal rod, and the metal rod is insulated from the electrode system. Wherein, electrodes A2, A2' and electrodes A1, A1' are shield electrodes, located at both ends of the electrode system, and the above-mentioned shield electrodes A2, A2' are connected by wires to emit shield current to focus the main current. The electrodes A0, A0' are main electrodes, located in the middle of the electrode system, which are divided into two parts by the electrodes M0, M0', and the electrodes A0, A0' are connected by wires to emit the main current. The electrode system also includes electrodes A1*, A1*', electrodes M2, M2', electrodes M1, M1', electrodes M0, M0' and other ring electrodes, the ring electrodes A1*, A1*' are respectively used to measure the shielding Voltage of electrodes A1, A1'. In addition, two pairs of ring electrodes M2, M2' and electrodes M1, M1' are used for voltage monitoring, while ring electrodes M0, M0' are located in the middle of the electrode system, and are used to measure the voltages of electrodes A0, A0' respectively.

That is to say, in the present invention, the electrodes A2 and A2' are directly connected together by wires, and then connected to the circuit; the electrodes A0 and A0' are directly connected by wires, and then connected to the circuit, while the other electrodes are connected by wires. connected directly to the circuit.

This embodiment discloses a logging method using the high-resolution dual lateral logging tool. According to the electric field superposition principle in software focusing, the logging method of the present invention can be decomposed into three independent modes of different frequencies, namely mode 1, mode 2 and mode 3, and the deep and shallow lateral focusing modes can adopt these three modes A combination of two or two is achieved.

2A and 2B are respectively Mode 1 and Mode 3 of the high-resolution dual lateral logging tool of the present invention. 3A and 3B are respectively Mode 2 and Mode 3 of the high-resolution dual lateral logging tool of the present invention.

、

、

、

，同时记录电极N的电位，记为

。As shown in FIG. 2A, in mode 1, the current output by the output module is loaded on electrodes A1, A1' and A2, A2', the auxiliary supervision circuit module keeps the electrodes A1* and A2 at the same potential, and the electrodes A1*' Equipotential with electrode A2', the data acquisition module records the potential of electrodes M2, M2' and electrodes M1, M1' in this mode, and denoted as

,

,

,

, while recording the potential of electrode N, denoted as

.

、

、

、

，同时记录电极N电位，记为

。As shown in FIG. 3A, in mode 2, the current output by the output module is loaded on the electrodes A1, A1' and returned to the electrodes A2, A2'. The data acquisition module records the potentials of electrodes M2, M2', and electrodes M1 and M1' in this mode, and denote them as

,

,

,

, while recording the electrode N potential, denoted as

.

、

、

、

、

、

，同时记录电极N电位，记为

；同时记录电极A0、A0’上的电流，记为

、

。As shown in FIG. 2B and FIG. 3B, in mode 3, the current output by the output module is loaded on the electrodes A0, A0', and on the return electrodes A1, A1' and the electrodes A2, A2', the supervision loop module keeps the electrodes A1* is equipotential with electrode A2, and electrode A1*' is equipotential with electrode A2'. The data acquisition module records the potentials of electrodes M2, M2', electrodes M1, M1', electrodes M0, M0' in this mode, and recorded as

,

,

,

,

,

, while recording the electrode N potential, denoted as

; Simultaneously record the current on electrodes A0 and A0', denoted as

,

.

Example 1

Fig. 2C is a deep lateral logging pattern synthesized by using the high-resolution dual lateral logging tool of the present invention. The formation apparent resistivity can be calculated using the data collected in the above three working modes. As shown in Figure 2C, the deep lateral apparent resistivity can be obtained by combining Mode 1 and Mode 3:

为深侧向仪器系数，in,

is the deep lateral instrument coefficient,

。

.

Example 2

FIG. 3C is a shallow lateral logging pattern synthesized by using the high-resolution dual lateral logging tool of the present invention. The formation apparent resistivity can be calculated using the data collected in the above three working modes. As shown in FIG. 3C, the shallow lateral apparent resistivity can be obtained by combining Mode 2 and Mode 3:

为浅侧向仪器系数，in,

is the shallow lateral instrument coefficient,

。

.

Using the data collected in the above three working modes, the following high-resolution deep and shallow lateral apparent resistivity curves can also be calculated:

、

分别为高分辨率深、浅侧向仪器系数，in,

,

are the high-resolution deep and shallow lateral instrument coefficients, respectively,

。

.

，提供更加精确的聚焦条件。In the present invention, electrodes A2 and A2' are short-circuited, electrodes A0 and A0' are short-circuited, and other electrodes are not short-circuited. Use the driving loop to control the potential difference between electrodes A1 and A1' to eliminate the vertical gradient formed in the center of the instrument, that is, to achieve

, providing more precise focusing conditions.

The invention adopts the soft focusing method, and the circuit implementation adopts the open-loop method, which is less affected by the peripheral environment, improves the measurement accuracy of the formation resistivity measurement, can effectively shorten the length of the double lateral logging tool, and improves the performance of the tool in complex wellbore. suitability in the environment. At the same time, the logging tool and logging method can identify and detect thin layers and thin interlayers of 0.1 m, and provide effective logging curves for thin layer logging.

The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced without Any modifications or partial substitutions that depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims (8)

1. The electrode system of the double lateral logging instrument comprises an electrode system and an insulating core rod, wherein the electrode system is composed of a plurality of electrodes arranged on the insulating core rod and is connected with a measuring circuit through a lead, and the electrode system is characterized in that

The plurality of electrodes are separated by adopting an insulating material, the center of the insulating core rod is a metal rod, the center of the metal rod is provided with a through hole, the metal rod is insulated from the electrode system, and the electrode system comprises:

main electrodes a0, a 0' disposed in the middle of the electrode train;

at least one pair of shield electrodes a2, a2 'and a1, a 1' emitting a shield current to focus the main current;

a plurality of pairs of voltage measuring electrodes a1, a1 'and M0, M0' that measure the electrode voltage; and

at least one pair of voltage monitoring electrodes M2, M2 'and M1, M1' for voltage monitoring,

wherein the shielding electrodes a2, a2 'are shorted, the main electrodes a0, a 0' are shorted, and the other electrodes are not shorted.

2. The dual laterolog tool electrode train of claim 1, wherein one of the pairs of voltage measurement electrodes M0, M0 'is located in the middle of the electrode train for measuring the voltage of the main electrodes a0, a 0', respectively.

3. The dual laterolog tool electrode train of claim 1, wherein the plurality of electrodes are arranged in series from one end of the electrode train to the other as a shield electrode a2, a voltage measurement electrode a1, a shield electrode a1, a voltage monitor electrode M2, a voltage monitor electrode M1, a main electrode a0, a voltage measurement electrode M0, a voltage measurement electrode M0 ', a main electrode a0 ', a voltage monitor electrode M1 ', a voltage monitor electrode M2 ', a shield electrode a1 ', a voltage measurement electrode a1 ', a shield electrode a2 '.

4. A dual laterolog tool for formation resistivity measurement, comprising the dual laterolog tool electrode system of any one of claims 1 to 3.

5. A method of formation resistivity measurements using the dual laterolog apparatus of claim 4, wherein said dual laterolog apparatus is operated in three modes:

in mode 1, the current output by the output module is loaded on the shielding electrodes A1 and A1 'and the shielding electrodes A2 and A2', the auxiliary monitoring circuit module keeps the voltage measuring electrode A1 and the shielding electrode A2 at the same potential, and the data acquisition module records the potentials of the voltage monitoring electrodes M2 and M2 'and the voltage monitoring electrodes M1 and M1' in the mode and records the potentials as

、

、

、

While recording the potential of electrode N, is recorded

；

In mode 2, the current output by the output module is loaded on the shielding electrodes A1 and A1 'and returns to the shielding electrodes A2 and A2', and the data acquisition module records the potentials of the voltage monitoring electrodes M2 and M2 'and the voltage monitoring electrodes M1 and M1' in the mode and records the potentials as

、

、

、

While recording the potential of electrode N, is recorded

；

In mode 3, the current output by the output module is applied to the main electrodes a0 and a0 ' and returned to the shielding electrodes a1 and a1 ' and the shielding electrodes a2 and a2 ', the monitoring circuit module keeps the voltage measuring electrode a1 equipotential with the shielding electrode a2, the voltage measuring electrode a1 equipotential with the shielding electrode a2 ', and the data acquisition module records the potentials of the voltage monitoring electrodes M2 and M2 ', the voltage monitoring electrodes M1 and M1 ', and the voltage measuring electrodes M0 and M0 ' in the mode and records the potentials as

、

、

、

、

、

While recording the potential of electrode N, is recorded

Recording the current on the main electrodes A0, A0', noted as

、

。

6. The formation resistivity measurement method of claim 5, using the mode 1 in combination with the mode 3, a deep lateral apparent resistivity can be obtained:

wherein,

in order to be a deep lateral instrumental factor,

。

7. the formation resistivity measurement method of claim 5, with the mode 2 combined with the mode 3, a shallow sideview resistivity can be obtained:

wherein,

is the coefficient of the shallow lateral instrument,

。

8. the method for measuring the formation resistivity according to any one of the claims 5 to 7, wherein the following high-resolution deep and shallow lateral resistivity curves can be calculated by using the data acquired in the three operation modes of the mode 1, the mode 2 and the mode 3:

wherein,

、

high resolution deep and shallow lateral instrument coefficients respectively,

。

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