CN108983298B - Oil-gas fracturing four-dimensional real-time electromagnetic monitoring method and system - Google Patents
Oil-gas fracturing four-dimensional real-time electromagnetic monitoring method and system Download PDFInfo
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Abstract
The embodiment of the invention provides a four-dimensional real-time electromagnetic monitoring method and a system for oil-gas fracturing, wherein the method comprises the following steps: in the construction process of each fracturing section, electromagnetic wave excitation signals with different frequencies are transmitted along the direction of a fracturing pilot hole well, and electric field signals before fracturing and electric field signals in the fracturing process of a plurality of monitoring points in the monitoring range of the fracturing pilot hole well are obtained; obtaining residual electric fields of all monitoring points based on electric field signals before fracturing and electric field signals in the fracturing process, and obtaining electric field residual degrees according to the residual electric fields; acquiring the spreading range and the fracturing effect of the fracturing fracture in the space based on the electric field residual degree of each monitoring point, transmitting an electromagnetic wave excitation signal and simultaneously receiving a feedback electric field signal, and monitoring the spreading range of the fracture section in the transverse and longitudinal directions by using the change characteristics of the electric field signal in the space and time; and analyzing the crack characteristics by utilizing the change curve characteristics of the electric field signals obtained by continuous observation along with the time, and judging whether the cracks are main large cracks or uniform crack networks.
Description
Technical Field
The embodiment of the invention relates to the technical field of oil and gas development in the field of exploration geophysical, in particular to a four-dimensional real-time electromagnetic monitoring method and system for oil and gas fracturing.
Background
In the field of petroleum, fracturing refers to a method of forming cracks in oil and gas layers by using the action of water power in the process of oil or gas production, and is also called hydraulic fracturing. Fracturing is the process of artificially cracking stratum, improving the flowing environment of oil in underground and increasing the yield of oil well, and plays an important role in improving the flowing condition of oil well bottom, slowing down the interlamination and improving the oil layer utilization condition. The hydraulic fracturing method comprises two categories of hydraulic fracturing and high-energy gas fracturing, wherein the hydraulic fracturing is that fluid is injected into a well at a high speed by a ground high-pressure pump truck group, and the rock of an oil layer is fractured to generate cracks by means of high pressure pumped up from the bottom of the well. In order to prevent the pressure from dropping and the crack from closing after the pump truck stops working, sand which is several times higher than the density of the stratum is mixed in the injected liquid after the stratum is broken, the sand and the fluid enter the crack and stay in the crack permanently, and the supporting crack is in an open state, so that the oil flow environment is improved for a long time. The current hydraulic fracturing technology is mature, and the oil well yield increasing effect is obvious, so that the hydraulic fracturing technology becomes a preferred common technology for people for a long time.
After the fracturing reformation measures are implemented on the oil and gas well, an effective monitoring method is needed to determine the fracturing operation effect and acquire a plurality of information such as the flow conductivity, the geometric shape, the complexity, the direction and the like of a fracturing induced fracture so as to improve the fracturing production increase operation effect of the shale gas reservoir and the productivity of the gas well and improve the shale gas recovery ratio. The monitoring method in the prior art comprises the following steps: underground micro-earthquake, direct near-wellbore fracture monitoring and distributed acoustic sensors.
The underground micro-seismic monitoring method is characterized in that according to the principle that micro-seismic events can be induced by fluid injection, the response characteristics of a returned wave field to gas storage layer cracks are utilized to carry out wave field response analysis, and the monitoring reaction result of corresponding fracturing is obtained; micro-seismic monitoring is a matching technology in the hydraulic fracturing modification process of a shale gas reservoir, but at present, due to the limitation of the micro-seismic monitoring technology, the growth process, the geometric shape and the spatial distribution of cracks of the hydraulic fracturing modification reservoir cannot be effectively and intuitively described due to the fact that signals are attenuated continuously when seismic waves are transmitted in a stratum, the noise of a shaft environment is large, the pump pressure and the pump speed are high and the like; the principle of a direct near wellbore fracture monitoring method is as follows: the monitoring technology is that the near-wellbore range fracture parameter information is inverted through the fluid physical characteristics of the shale gas well after logging and fracturing, and the monitoring technology mainly comprises an isotope tracer method, temperature logging and the like; however, the direct near-wellbore fracture monitoring method does not have a real-time monitoring function, has a small monitoring range and can only be used as a supplementary means generally; the distributed acoustic sensing monitoring method is characterized in that the optical fiber is used as a sound sensing transmission medium to monitor the sound distribution condition along the optical fiber in real time, and further crack information is obtained; the distributed sound sensor monitoring method has good reaction on the inclination angle and the direction of the crack, but cannot effectively react on data of the width, the height and the like of the complex crack.
Disclosure of Invention
The embodiment of the invention provides a four-dimensional real-time electromagnetic monitoring method and system for oil-gas fracturing, which are used for solving the problem that the growth process, the geometric shape and the spatial distribution of a fracture of a hydraulic fracturing modified reservoir cannot be visually and comprehensively depicted in the prior art.
The embodiment of the invention provides a four-dimensional real-time electromagnetic monitoring method for oil-gas fracturing, which comprises the following steps:
in the construction process of each fracturing section, electromagnetic wave excitation signals containing different frequencies are simultaneously transmitted to a fracturing target layer at a set distance in a direction parallel to or vertical to a horizontal well, and an electric field signal or a magnetic field signal before fracturing and an electric field signal or a magnetic field signal in the fracturing process at a plurality of monitoring points in the monitoring range of the fracturing pilot hole well are obtained;
obtaining a residual electric field or a residual magnetic field or residual resistivity of each monitoring point based on an electric field signal or a magnetic field signal before fracturing and an electric field signal or a magnetic field signal in the fracturing process, and obtaining an electric field residual degree or a magnetic field residual degree or a resistivity residual degree, a first-order second-order space vector difference and a second-order time domain vector difference corresponding to the electric field residual degree or the magnetic field residual degree or the resistivity residual degree according to the residual electric field residual or the residual magnetic field residual resistivity;
and acquiring the geometric distribution range of the fracturing fracture in the space, the main fracture network fracture characteristic evaluation and the intersegmental fracturing fluid series flow evaluation based on the residual electric field, the residual magnetic field, the residual resistivity and the time domain difference of each monitoring point, the electric field residual degree, the magnetic field residual degree or the resistivity residual degree, the corresponding first-order second-order space vector difference and the corresponding second-order time domain vector difference.
Preferably, each fracturing segment further comprises, before construction:
and arranging a signal emission source comprising a plurality of main frequencies and harmonic waves outside the fracturing target layer at a set distance in a direction parallel to or vertical to the horizontal well, wherein the signal emission source comprises an electromagnetic wave excitation signal excitation source and an electric dipole.
Preferably, each fracturing segment further comprises, before construction:
and a plurality of monitoring points are arranged in the monitoring range of the fracturing pilot hole well, and each monitoring point is provided with an electric field monitoring sensor or a magnetic field monitoring sensor and is used for continuously monitoring electric field signals or magnetic field signals of the fracturing target layer of each fracturing section at different fracturing times in response to the electromagnetic wave excitation signals.
Preferably, after the electromagnetic wave excitation signals with different frequencies are transmitted to the fracturing target layer at a set distance in a direction parallel to or perpendicular to the horizontal well, the method further comprises the following steps:
and recording the current intensity corresponding to the electromagnetic wave excitation signals with different frequencies.
Preferably, the obtaining of the residual electric field or the residual magnetic field of each monitoring point based on the electric field signal or the magnetic field signal before fracturing and the electric field signal or the magnetic field signal during fracturing specifically includes:
the method comprises the steps of obtaining an electric field signal or a magnetic field signal of a monitoring point before fracturing and an electric field signal or a magnetic field signal corresponding to an electromagnetic wave excitation signal with different frequencies in the fracturing process, normalizing the electric field signal or the magnetic field signal in the fracturing process according to the current intensity corresponding to the electromagnetic wave excitation signal with different frequencies, and obtaining a residual electric field or a residual magnetic field of the monitoring point according to the electric field signal or the magnetic field signal of the monitoring point before fracturing.
Preferably, the obtaining of the electric field residual degree or the magnetic field residual degree or the resistivity residual degree according to the residual electric field or the residual magnetic field specifically includes:
and obtaining a frequency-residual electric field or frequency-residual magnetic field or frequency-residual resistivity relation based on the residual electric field or residual magnetic field, and performing integration processing on negative anomalies in the frequency-residual electric field or frequency-residual magnetic field or frequency-residual resistivity relation to obtain an electric field residual degree or magnetic field residual degree or resistivity residual degree, and a corresponding first-order second-order space vector difference and a corresponding second-order time domain vector difference.
Preferably, the method for evaluating the geometrical spread range of the fracturing fracture in the space, the main fracture network fracture characteristic and the intersegment fracturing fluid series flow comprises the following steps of:
obtaining a plane contour map according to the electric field residual degree or the magnetic field residual degree or the resistivity residual degree of each monitoring point of all the fracturing sections and corresponding first-order second-order space vector difference and second-order time domain vector difference, and monitoring the geometric distribution range of the fracturing fracture in the space according to the plane contour map, wherein the monitoring comprises the monitoring of the length, width and height of the fracture;
judging whether the fracturing fracture is a main large fracture or a uniform fracture network according to the change characteristics of the electric field or magnetic field signal along with time;
and judging whether the fracturing fluid is guided to a fracture network of the adjacent fracturing section in the construction process of the current fracturing section by monitoring the electromagnetic field data of the fracturing section adjacent to the current fracturing section.
A four-dimensional real-time electromagnetic monitoring system for oil and gas fracturing comprises:
the electromagnetic wave excitation source is used for emitting electromagnetic wave excitation signals with different frequencies to the fracturing target layer at a set distance in a direction parallel to or vertical to the horizontal well;
the electric field or magnetic field signal monitoring device is used for acquiring electric field signals or magnetic field signals before fracturing and electric field signals or magnetic field signals in the fracturing process at a plurality of monitoring points in the fracturing pilot hole monitoring range;
the signal processor is used for solving a residual electric field or a residual magnetic field or residual resistivity of each monitoring point obtained based on an electric field signal or a magnetic field signal before fracturing and an electric field signal or a magnetic field signal in the fracturing process, obtaining an electric field residual degree or a magnetic field residual degree or a resistivity residual degree according to the residual electric field or the residual magnetic field or the residual resistivity, and obtaining a first-order second-order space vector difference and a second-order time domain vector difference corresponding to the electric field residual degree or the magnetic field residual degree or the resistivity residual degree; and acquiring the geometric distribution range of the fracturing fracture in the space, the main fracture network fracture characteristic evaluation and the intersegmental fracturing fluid series flow evaluation based on the residual electric field, the residual magnetic field, the residual resistivity and the time domain difference of each monitoring point, the electric field residual degree, the magnetic field residual degree or the resistivity residual degree, the corresponding first-order second-order space vector difference and the corresponding second-order time domain vector difference.
Preferably, the electric field or magnetic field signal monitoring device comprises a plurality of electric field monitoring sensors or magnetic field monitoring sensors and a monitoring receiving host, the electric field monitoring sensors or magnetic field monitoring sensors are arranged in the monitoring range of the fracturing pilot hole, the electric field monitoring sensors or magnetic field monitoring sensors are connected with the monitoring receiving host, and the monitoring receiving host is used for continuously monitoring electric field signals or magnetic field signals of fracturing target layers of different fracturing periods of each fracturing section, which respond to electromagnetic wave excitation signals.
Preferably, the electromagnetic wave excitation source comprises an electromagnetic wave excitation signal excitation source and an electric dipole.
According to the oil-gas fracturing four-dimensional real-time electromagnetic monitoring method and system, the electromagnetic wave excitation signal is transmitted, the feedback electric field or magnetic field signal is received, and the change characteristics of the electric field or magnetic field signal in space and time are utilized to monitor the fracture section transverse and longitudinal distribution fracture spreading range; the ideal effect of oil and gas fracturing is that a uniform fracture network is formed after fracturing construction, the change curve characteristic of an electric field or magnetic field signal along with time is obtained by continuous observation to analyze the fracture characteristic, and whether the fracture formed by fracturing is a main large fracture or an ideal uniform fracture network can be inferred; and analyzing and judging whether the fracturing fluid of the current fracturing section flows into the adjacent fracturing section or not by observing the change of the electromagnetic field data of the fracturing section adjacent to the current fracturing section.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a flow chart of a real-time electromagnetic monitoring method for oil and gas fracturing according to the present invention;
FIG. 2 is a characteristic diagram of a main large crack and uniform crack network monitoring curve of the invention;
FIG. 3 is a graph of percentage of differential electric field for single point monitoring according to the present invention;
FIG. 4 is a block diagram of an embodiment of a real-time electromagnetic monitoring system for oil and gas fracturing.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, a four-dimensional real-time electromagnetic monitoring method for oil and gas fracturing is shown, which comprises the following steps:
in the construction process of each fracturing section, electromagnetic wave excitation signals with different frequencies are transmitted to a fracturing target layer at a certain distance (set distance) in a direction parallel to or vertical to a horizontal well, and electric field or magnetic field signals before fracturing and electric field or magnetic field signals in the fracturing process at a plurality of monitoring points in the monitoring range of a fracturing pilot hole well are obtained; before the construction of each fracturing section is started, electromagnetic wave excitation signals with different frequencies are transmitted through a transmitting source, and data are fed back by continuously observing electric field or magnetic field signals on each monitoring point until the construction of the fracturing section is finished; the variation characteristics of the electric field or magnetic field signals fed back in space and time can be utilized to monitor the fracture section transverse and longitudinal distribution fracture spreading range.
Specifically, a residual electric field or a residual magnetic field of each monitoring point is obtained based on an electric field or a magnetic field signal before fracturing and an electric field or a magnetic field signal in the fracturing process, and an electric field or a magnetic field residual degree or a resistivity residual degree, a first-order second-order space vector difference (namely a first-order space vector difference and a second-order space vector difference) and a second-order time domain vector difference (namely a first-order time domain vector difference and a second-order time domain vector difference) are obtained according to the residual electric field or the residual magnetic field; differential calculation is carried out on electric field or magnetic field signals monitored at different times during fracturing construction by taking the electric field or magnetic field signals measured before fracturing as a reference, a residual electric field or residual magnetic field is obtained, and fracturing wave conditions of each monitoring station in a monitoring range can be analyzed; the electric field or magnetic field residual error degree or resistivity residual error degree, first-order second-order space vector difference and second-order time domain vector difference are obtained by utilizing the negative abnormal integration of the residual electric field or residual magnetic field of each monitoring point, and the fracturing effect of a single monitoring point can be analyzed;
acquiring the spatial spread range and the fracturing effect of the fracturing fracture based on the electric field or magnetic field residue degree or resistivity residue degree of each monitoring point and the first-order second-order space vector difference and the second-order time vector difference thereof; the characteristics of the single-section fracture network can be judged by utilizing the curve of the normalized electric field or magnetic field changing along with time in a single monitoring station, whether a uniform fracture network or a plurality of main large fractures are formed or not is judged, and the fracturing effect is evaluated, wherein the larger the residual degree of the electric field or the magnetic field or the residual degree of the resistivity is, the better the fracturing effect is, and the worse the fracturing effect is otherwise. And judging whether the fracturing fluid of the current fracturing section flows into the adjacent fracturing section or not by observing the electromagnetic field data change of the fracturing section adjacent to the current fracturing section.
Specifically, in this embodiment, before each fracturing segment is constructed, the method further includes:
and arranging a signal emission source comprising a plurality of main frequencies and harmonic waves outside the fracturing target layer at a certain distance in a direction parallel to or vertical to the horizontal well, wherein the signal emission source comprises an electromagnetic wave excitation signal excitation source and electric dipoles (electrodes A and B).
In this embodiment, acquiring an electric field or a magnetic field signal before fracturing and an electric field or a magnetic field signal during fracturing at a plurality of monitoring points within a fracture pilot hole monitoring range specifically includes:
and a plurality of monitoring points are arranged in the monitoring range of the fracturing pilot hole well, and each monitoring point is provided with an electric field (or magnetic field) monitoring sensor for continuously monitoring electric field or magnetic field signals of the fracturing target layer of each fracturing section at different fracturing times in response to the electromagnetic wave excitation signals.
In this embodiment, after the electromagnetic wave excitation signals with different frequencies are emitted to the fracturing target layer at a certain distance in a direction parallel to or perpendicular to the horizontal well, the method further includes:
and recording the current intensities corresponding to the electromagnetic wave excitation signals with different frequencies, normalizing the electric field or magnetic field signals by using the current intensities obtained by the signal transmitting station, and drawing the normalized electric field or magnetic field signal intensities in different fracturing time periods into a frequency-resistivity curve.
Specifically, obtaining a residual electric field or a residual magnetic field of each monitoring point based on an electric field or a magnetic field signal before fracturing and an electric field or a magnetic field signal in a fracturing process specifically includes:
acquiring electric field or magnetic field signals of monitoring points before fracturing and electric field or magnetic field signals corresponding to electromagnetic wave excitation signals with different frequencies in the fracturing process, normalizing the electric field or magnetic field signals in the fracturing process according to the current intensities corresponding to the electromagnetic wave excitation signals with different frequencies, carrying out differential calculation on the electric field or magnetic field signals monitored at different times in the fracturing construction period by taking the electric field or magnetic field signals measured before fracturing as a reference to obtain residual electric fields or residual magnetic fields of the monitoring points, drawing frequency-residual electric fields or residual magnetic field curves by using the residual electric fields or residual magnetic fields, and analyzing and deducing the transverse spread range of each section of fracturing fracture by using the residual electric fields or residual magnetic field curves of the monitoring points.
Specifically, in this embodiment, the outline of the process of calculating the residual electric field or the residual magnetic field is as follows:
the monitoring receiver firstly obtains potential difference data of each monitoring point in different fracturing stages to calculate an electric field, Eif＝ΔVif/(IifMN) using a magnetic bar to collect HifWhere i represents the location of the monitored point, f represents the frequency, and MN represents the distance of the monitored point.
Calculating a residual electric field or a residual magnetic field or residual resistivity by using potential difference data of each monitoring point before and in the fracturing process, wherein the formula is as follows:
wherein t is0Before fracturing, t represents a certain moment in the fracturing process, and is a signal percentage curve chart of a single-point monitoring differential electric field or magnetic field as shown in figure 2.
In this embodiment, obtaining the residual electric field or magnetic field residual or resistivity residual and the first-order second-order space vector difference and the second-order time vector difference thereof according to the residual electric field or residual magnetic field specifically includes:
and obtaining a frequency-residual electric field or residual magnetic field relation based on the residual electric field or residual magnetic field, and performing integration processing on negative anomalies in the frequency-residual electric field or residual magnetic field relation to obtain electric field or magnetic field residual degree or resistivity residual degree, a first-order second-order space vector difference and a second-order time domain vector difference.
Specifically, a frequency-residual electric field or residual magnetic field curve is drawn by using a residual electric field or a residual magnetic field, and the transverse spread range of each section of the fracturing fracture is analyzed and deduced by using the frequency-residual electric field or residual magnetic field curve of each monitoring point. And integrating the negative anomaly in the frequency-residual electric field or residual magnetic field curve to form a parameter-electric field or magnetic field residual degree or resistivity residual degree for evaluating the single-point fracturing effect, and a first-order second-order space vector difference and a second-order time domain vector difference thereof.
The formulas for calculating the electric field residual degree, the magnetic field residual degree and the resistivity residual degree are respectively as follows:
the above formula represents the electric field or magnetic field residual degree or resistivity residual degree at the ith monitoring point t in the fracturing process.
Specifically, in this embodiment, the method for obtaining the spatial distribution range and the fracturing effect of the fracture based on the electric field or magnetic field residual degree or resistivity residual degree of each monitoring point and the first-order second-order space vector difference and the second-order time vector difference thereof specifically includes:
drawing a frequency-residual electric field or residual magnetic field curve by using a residual electric field or a residual magnetic field, and analyzing and deducing the transverse wave coverage of each section of the fracturing fracture by using the residual electric field or the residual magnetic field curve of each monitoring point, wherein the transverse wave coverage comprises the length, the width and the modification volume of the fracture; the method comprises the steps that the longitudinal thickness and the height of a fractured fracture are obtained by analyzing the frequency-residual electric field or residual magnetic field curve characteristics of each monitoring point and combining with a monitoring response quantity plate established according to a fracturing well earth electric model; the method comprises the following steps of monitoring the geometric spreading range of transverse and longitudinal distributed fractures of a fracturing section by utilizing the change characteristics of a feedback electric field or magnetic field signal in space and time;
drawing a plane contour map by using the electric field or magnetic field residual degree or resistivity residual degree of each monitoring point of all fracturing sections, and deducing the spreading range and the fracturing effect of the fracturing fracture in the space, wherein the larger the electric field or magnetic field residual degree or resistivity residual degree is, the better the fracturing effect is, and otherwise, the fracturing effect is poor; the ideal effect of oil and gas fracturing is that a uniform fracture network is formed after fracturing construction, in the embodiment, the characteristics of the fractures are analyzed by using the characteristics of the change curve of the electric field along with time obtained by continuous observation, and whether the fractures formed by fracturing are main large fractures or uniform fracture networks can be inferred.
And the fracture characteristics can be judged by drawing a curve graph according to the change of the normalized electric field or magnetic field signals of each monitoring point along with the fracture time. As shown in fig. 3, the solid line shows that the normalized electric field or magnetic field signal is gradually and uniformly reduced as the fracturing time advances, and the characteristic shows that the target layer forms a uniform fracture network, so that the fracturing effect is good; and the electric field that the dotted line represents reduces rapidly in fracturing earlier stage, and it is gentle in the middle and later stages's of fracturing change, and this kind of characteristic shows that the target zone forms a plurality of main big cracks, is unfavorable for the release of reservoir oil gas, and fracturing effect is not good.
This embodiment still includes a four-dimensional real-time electromagnetic monitoring system of oil and gas fracturing, as shown in fig. 4, includes:
the electromagnetic wave excitation source is used for emitting electromagnetic wave excitation signals with different frequencies to the fracturing target layer at a certain distance in a direction parallel to or vertical to the horizontal well;
the electric field or magnetic field signal monitoring device is used for acquiring electric field or magnetic field signals of a plurality of monitoring points in the monitoring range of the fracturing pilot hole well before fracturing and electric field or magnetic field signals in the fracturing process;
electric field, magnetic field data that the sensor was gathered transmit fracturing command car through wireless communication, and fracturing command car carries on signal processor and achievement show platform.
The signal processor is used for obtaining a residual electric field or a residual magnetic field of each monitoring point based on an electric field or a magnetic field signal before fracturing and an electric field or a magnetic field signal in the fracturing process, and obtaining an electric field or a magnetic field residual degree or a resistivity residual degree and a first-order second-order space vector difference and a second-order time domain vector difference thereof according to the residual electric field or the residual magnetic field; and obtaining the spatial spread range and the fracturing effect of the fracturing fracture based on the electric field or magnetic field residue degree or resistivity residue degree of each monitoring point, the first-order second-order space vector difference and the second-order time vector difference.
Specifically, in this embodiment, electric field or magnetic field signal monitoring devices include a plurality of electric field (or magnetic field) monitoring sensors and monitoring receiver, electric field (or magnetic field) monitoring sensors arrange in fracturing pilot hole monitoring range, just electric field (or magnetic field) monitoring sensors connect monitoring receiver, monitoring receiver is used for the electric field or the magnetic field signal of each different fracturing time fracturing target layer of fracturing section to electromagnetic wave excitation signal response in succession.
Specifically, in this embodiment, the electromagnetic wave excitation source includes an electromagnetic wave excitation signal excitation source and an electric dipole.
In summary, according to the four-dimensional real-time electromagnetic monitoring method and system for oil-gas fracturing provided by the embodiment of the invention, by transmitting electromagnetic wave excitation signals and receiving feedback electric field or magnetic field signals at the same time, the spreading ranges of the transverse and longitudinal distributed fractures of the fracturing section are monitored by using the change characteristics of the electric field or magnetic field signals in space and time; the ideal effect of oil and gas fracturing is that a uniform fracture network is formed after fracturing construction, the change curve characteristic of an electric field or magnetic field signal along with time is obtained by continuous observation to analyze the fracture characteristic, and whether the fracture formed by fracturing is a main large fracture or a uniform fracture network can be inferred; the fracturing of oil and gas resources can be efficiently, economically and effectively monitored in real time, the parameters of electric field, magnetic field and resistivity of four dimensions (x, y, z and t) of a fracturing target area are obtained, the fracturing effect of each fracturing section of a fracturing well is evaluated, the fracturing operation construction is effectively guided, the drilling parameters are optimized, the fracturing monitoring cost is greatly reduced, and the fracturing monitoring effect is improved, so that the yield of a single well is improved, and the method plays an important role in improving the yield of the single well in the development process of the oil and gas resources in China.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of the embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A four-dimensional real-time electromagnetic monitoring method for oil and gas fracturing is characterized by comprising the following steps:
in the construction process of each fracturing section, electromagnetic wave excitation signals containing different frequencies are simultaneously transmitted to a fracturing target layer at a set distance in a direction parallel to or vertical to a horizontal well, and an electric field signal or a magnetic field signal before fracturing and an electric field signal or a magnetic field signal in the fracturing process at a plurality of monitoring points in the monitoring range of the fracturing pilot hole well are obtained;
obtaining a residual electric field or a residual magnetic field or residual resistivity of each monitoring point based on an electric field signal or a magnetic field signal before fracturing and an electric field signal or a magnetic field signal in the fracturing process, and obtaining an electric field residual degree or a magnetic field residual degree or a resistivity residual degree, a first-order second-order space vector difference and a second-order time domain vector difference corresponding to the electric field residual degree or the magnetic field residual degree or the resistivity residual degree according to the residual electric field residual or the residual magnetic field residual resistivity;
acquiring a geometric spread range of a fracturing fracture in a space, evaluation of main fracture network fracture characteristics and evaluation of an intersegment fracturing fluid series flow based on a residual electric field, a residual magnetic field, residual resistivity and corresponding time domain difference of each monitoring point, as well as electric field residual degree or magnetic field residual degree or resistivity residual degree, corresponding first-order second-order space vector difference and corresponding second-order time domain vector difference;
the method for obtaining the residual electric field or residual magnetic field or residual resistivity of each monitoring point based on the electric field signal or magnetic field signal before fracturing and the electric field signal or magnetic field signal in the fracturing process specifically comprises the following steps:
acquiring an electric field signal or a magnetic field signal of a monitoring point before fracturing and an electric field signal or a magnetic field signal corresponding to an electromagnetic wave excitation signal with different frequencies in the fracturing process, normalizing the electric field signal or the magnetic field signal in the fracturing process according to the current intensity corresponding to the electromagnetic wave excitation signal with different frequencies, and obtaining a residual electric field or a residual magnetic field or residual resistivity of the monitoring point according to the electric field signal or the magnetic field signal of the monitoring point before fracturing;
the obtaining of the electric field residual degree or the magnetic field residual degree or the resistivity residual degree according to the residual electric field or the residual magnetic field specifically includes:
and obtaining a relation of frequency-residual electric field or frequency-residual magnetic field or frequency-residual resistivity based on the residual electric field or residual magnetic field, and performing integration processing on negative anomalies in the relation of the frequency-residual electric field or frequency-residual magnetic field or frequency-residual resistivity to obtain electric field residual degree or magnetic field residual degree or resistivity residual degree, and corresponding first-order second-order space vector difference and second-order time domain vector difference.
2. The method for four-dimensional real-time electromagnetic monitoring of hydrocarbon fracturing of claim 1, wherein each fracturing section further comprises, before construction:
and arranging a signal emission source comprising a plurality of main frequencies and harmonic waves outside the fracturing target layer at a set distance in a direction parallel to or vertical to the horizontal well, wherein the signal emission source comprises an electromagnetic wave excitation signal excitation source and an electric dipole.
3. The method for four-dimensional real-time electromagnetic monitoring of hydrocarbon fracturing of claim 1, wherein each fracturing section further comprises, before construction:
and a plurality of monitoring points are arranged in the monitoring range of the fracturing pilot hole well, and each monitoring point is provided with an electric field monitoring sensor or a magnetic field monitoring sensor and is used for continuously monitoring electric field signals or magnetic field signals of the fracturing target layer of each fracturing section at different fracturing times in response to the electromagnetic wave excitation signals.
4. The oil and gas fracturing four-dimensional real-time electromagnetic monitoring method of claim 1, wherein after transmitting electromagnetic wave excitation signals of different frequencies to a fracturing target layer outside a set distance in a direction parallel or perpendicular to a horizontal well, the method further comprises:
and recording the current intensity corresponding to the electromagnetic wave excitation signals with different frequencies.
5. The oil and gas fracturing four-dimensional real-time electromagnetic monitoring method of claim 1, wherein the geometric spread range of the fracturing fracture in space, the evaluation of the main fracture network fracture characteristics and the evaluation of the fracturing fluid stream between stages are obtained based on the electric field or magnetic field residue or resistivity residue of each monitoring point and the first-order second-order space vector difference and the second-order time vector difference thereof, and specifically comprises the following steps:
obtaining a plane contour map according to the electric field residual degree or the magnetic field residual degree or the resistivity residual degree of each monitoring point of all the fracturing sections and corresponding first-order second-order space vector difference and second-order time domain vector difference, and monitoring the geometric distribution range of the fracturing fracture in the space according to the plane contour map, wherein the monitoring comprises the monitoring of the length, width and height of the fracture;
judging whether the fracturing fracture is a main large fracture or a uniform fracture network according to the change characteristics of the electric field or magnetic field signal along with time;
and judging whether the fracturing fluid is guided to a fracture network of the adjacent fracturing section in the construction process of the current fracturing section by monitoring the electromagnetic field data of the fracturing section adjacent to the current fracturing section.
6. The utility model provides a four-dimensional real-time electromagnetic monitoring system of oil gas fracturing which characterized in that includes:
the electromagnetic wave excitation source is used for emitting electromagnetic wave excitation signals with different frequencies to the fracturing target layer at a set distance in a direction parallel to or vertical to the horizontal well;
the electric field or magnetic field signal monitoring device is used for acquiring electric field signals or magnetic field signals before fracturing and electric field signals or magnetic field signals in the fracturing process at a plurality of monitoring points in the fracturing pilot hole monitoring range;
the signal processor is used for solving a residual electric field or a residual magnetic field or residual resistivity of each monitoring point obtained based on an electric field signal or a magnetic field signal before fracturing and an electric field signal or a magnetic field signal in the fracturing process, obtaining an electric field residual degree or a magnetic field residual degree or a resistivity residual degree according to the residual electric field or the residual magnetic field or the residual resistivity, and obtaining a first-order second-order space vector difference and a second-order time domain vector difference corresponding to the electric field residual degree or the magnetic field residual degree or the resistivity residual degree; acquiring a geometric distribution range of the fracturing fracture in the space, evaluation of main fracture network characteristics and evaluation of inter-stage fracturing fluid series flow based on a residual electric field, a residual magnetic field, residual resistivity and time domain difference of each monitoring point, electric field residual degree or magnetic field residual degree or resistivity residual degree, a corresponding first-order second-order space vector difference and a corresponding second-order time domain vector difference;
the method for obtaining the residual electric field or residual magnetic field or residual resistivity of each monitoring point based on the electric field signal or magnetic field signal before fracturing and the electric field signal or magnetic field signal in the fracturing process specifically comprises the following steps:
acquiring an electric field signal or a magnetic field signal of a monitoring point before fracturing and an electric field signal or a magnetic field signal corresponding to an electromagnetic wave excitation signal with different frequencies in the fracturing process, normalizing the electric field signal or the magnetic field signal in the fracturing process according to the current intensity corresponding to the electromagnetic wave excitation signal with different frequencies, and obtaining a residual electric field or a residual magnetic field or residual resistivity of the monitoring point according to the electric field signal or the magnetic field signal of the monitoring point before fracturing;
the obtaining of the electric field residual degree or the magnetic field residual degree or the resistivity residual degree according to the residual electric field or the residual magnetic field specifically includes:
and obtaining a relation of frequency-residual electric field or frequency-residual magnetic field or frequency-residual resistivity based on the residual electric field or residual magnetic field, and performing integration processing on negative anomalies in the relation of the frequency-residual electric field or frequency-residual magnetic field or frequency-residual resistivity to obtain electric field residual degree or magnetic field residual degree or resistivity residual degree, and corresponding first-order second-order space vector difference and second-order time domain vector difference.
7. The system for four-dimensional real-time electromagnetic monitoring for hydrocarbon fracturing of claim 6, wherein the device for monitoring electric field or magnetic field signals comprises a plurality of electric field monitoring sensors or magnetic field monitoring sensors and a monitoring receiving host, the electric field monitoring sensors or magnetic field monitoring sensors are arranged in the monitoring range of the fracturing pilot hole, the electric field monitoring sensors or magnetic field monitoring sensors are connected with the monitoring receiving host, and the monitoring receiving host is used for continuously monitoring electric field signals or magnetic field signals of fracturing target layers in different fracturing time of each fracturing section, which respond to electromagnetic wave excitation signals.
8. The system of claim 6, wherein the electromagnetic wave excitation source comprises an electromagnetic wave excitation signal excitation source and an electric dipole.
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| CN112302636A (en) * | 2019-07-26 | 2021-02-02 | 中国石油天然气集团有限公司 | Hydraulic fracturing monitoring method and device |
| CN110501746A (en) * | 2019-08-19 | 2019-11-26 | 孙启隆 | Roller three-dimensional controllable source electrical method monitoring and evaluation drilling fracturing method |
| CN110865245B (en) * | 2019-10-12 | 2021-10-26 | 陈国能 | Single-hole monitoring system and method for fracture diffusion electric field intensity |
| CN111123369B (en) * | 2020-01-06 | 2021-11-30 | 湖南省有色地质勘查局二四七队 | Geological exploration wave detection method, device, equipment and medium |
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