CN112147687B - Reservoir gas content prediction method and prediction system - Google Patents
Reservoir gas content prediction method and prediction system Download PDFInfo
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Abstract
The invention discloses a reservoir gas-bearing property prediction method and a prediction system, comprising the following steps: analyzing the reservoir acoustic curve to obtain the value domain characteristics of the gas-containing section of the reservoir acoustic; reconstructing a reservoir gas-containing section acoustic curve based on the value domain characteristics of the reservoir gas-containing section acoustic; and performing wave impedance inversion based on the reconstructed acoustic curve of the gas-containing section of the reservoir to predict the gas-containing property of the reservoir. According to the reservoir gas-containing property prediction method and the prediction system, under the condition that the acoustic impedance difference between the gas-containing section and the non-gas-containing section of the reservoir is not obvious, the acoustic curve of the gas-containing section is reconstructed, the acoustic value of the gas-containing section is highlighted to be different from the acoustic curve of the non-gas-containing section, and wave impedance inversion is carried out on the basis of the reconstructed gas-containing section acoustic curve, so that the gas-containing section of the reservoir is accurately distinguished, and the gas-containing section of the reservoir is simply and accurately predicted.
Description
Technical Field
The invention belongs to the field of oil and gas exploration and development, and particularly relates to a reservoir gas content prediction method and a reservoir gas content prediction system.
Background
Since the 90 s of the twentieth century, China has increased the exploration of natural gas, and the exploration reserves are rapidly and steadily increased every year, but the exploration degree is still very low, and is only 6.7%. As the extent of exploration and development increases, reservoir evaluation and gas bearing predictions become a core part of the work. The wave impedance is the product of density and speed, is one of important parameters for describing the lithology of the stratum, and utilizes the wave impedance to carry out wave impedance inversion to predict the reservoir distribution. At present, the reservoir and the reservoir gas content are predicted by adopting a method of distinguishing and then inverting the wave impedance difference between a reservoir or a reservoir gas-containing section and surrounding rock. The lithologic wave impedance characteristics of different regions are different, and when the difference between the wave impedance value of a gas-containing section of a reservoir in a target region and the wave impedance value of a reservoir in a non-gas-containing section is small, how to carry out inversion prediction on the gas-containing property of the reservoir is a problem which is often encountered.
When the difference between a reservoir of a gas-containing section and surrounding rock is not obvious, the wave impedance curve is reconstructed by using the constraint or explanation result of other logging curves at present, and wave impedance inversion is carried out by using the reconstructed wave impedance curve so as to predict the gas content of the reservoir. Along with the continuous deepening of the oil and gas exploration degree, inversion is carried out by adopting a logging curve reconstruction technology when the wave impedance difference between a reservoir and a surrounding rock is not obvious, and the method is one of methods for predicting the gas content of the reservoir. Currently, there are 4 common well log reconstruction techniques: (1) the method is used for correcting the curve of the conventional logging curve, and only abnormal values of the acoustic curve which are interfered are corrected; (2) an empirical formula or statistical fitting, wherein the method adopts the empirical formula to calculate the acoustic curve, or obtains the acoustic curve according to the fitting curve relationship of the intersection of the two curves (for example, the acoustic curve is obtained by the density of the Gardner formula, the acoustic curve is obtained by the resistance rate of the Faust formula, etc.); (3) information statistics weighting, in which natural gamma, natural potential, density, resistivity and other curves are added into the acoustic curve according to a given weight so as to highlight lithological reaction of the reconstructed acoustic curve; (4) based on the reconstruction technology of wavelet transformation, the wavelet transformation is carried out after various well logging data are subjected to standardization processing, the regional characteristics of different frequency bands are selected according to the resolution, and finally, the reconstructed acoustic wave curve is obtained through inverse transformation. In the aspect of quantitative prediction of fluid saturation, the Zhu military (2017) proposes that a sound wave curve and a wave impedance curve cannot effectively identify a sandstone reservoir stratum and a mudstone layer, a gamma curve and a density curve can well identify the reservoir stratum, in order to improve lithology identification capability of the sound wave curve, the density curve is adopted to reconstruct the sound wave curve, prediction is carried out, and a good prediction result is obtained. The spaciousness bright (2009) predicts the favorable area by utilizing the gamma curve reconstruction sound wave inversion technology, effectively improves the resolution of the inversion section and obtains good effect. The Jiangzhou (2016) proposes that when the wave impedance difference between a reservoir and a non-reservoir is not obvious, the reservoir prediction is carried out by utilizing a gamma curve reconstruction sound wave inversion technology, and a good effect is obtained. The Luwei (2016) utilizes the high-frequency component of the resistivity and the low-frequency component of the acoustic curve to construct an acoustic simulation curve, and utilizes the acoustic simulation curve to perform seismic inversion research. The good effect is obtained.
In reservoir prediction, under the influence of various factors such as the well environment, stratum compaction and the like, sometimes the acoustic curve cannot well reflect the lithology change of the stratum, especially the wave impedance change of a gas-containing section in the reservoir, and wave impedance inversion cannot effectively distinguish the lithology and predict the gas-containing distribution condition of the reservoir. This is a difficult point. In the prior art, other sensitive parameter curves are generally searched, and the wave impedance curve is reconstructed by using the other sensitive parameter curves. However, the main problems of this method are: under the condition that the wave impedance of a gas-containing segment and a non-gas-containing segment of a reservoir are not distinguished obviously, a pseudo-wave impedance curve with the wave impedance dimension is obtained, and the difference between the pseudo-wave impedance curve and an original wave impedance curve is large, so that the gas-containing distribution condition of the reservoir cannot be effectively predicted, and therefore a method for effectively and accurately predicting the gas-containing distribution condition of the reservoir is particularly needed.
Disclosure of Invention
The invention aims to effectively and accurately predict the gas-bearing distribution condition of a reservoir.
In order to achieve the above object, the present invention provides a reservoir gas bearing capacity prediction method, including: analyzing the reservoir acoustic curve to obtain the value domain characteristics of the gas-containing section of the reservoir acoustic; reconstructing a reservoir gas-containing section acoustic curve based on the value domain characteristics of the reservoir gas-containing section acoustic; and performing wave impedance inversion based on the reconstructed acoustic curve of the gas-containing section of the reservoir to predict the gas-containing property of the reservoir.
Preferably, analyzing the reservoir acoustic curve to obtain the value domain characteristics of the reservoir acoustic gas-containing section comprises: and acquiring the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section based on the reservoir lithology analysis.
Preferably, the analyzing the reservoir acoustic curve comprises: and performing value domain analysis of acoustic lithology and value domain analysis of the acoustic gas-containing section on the reservoir acoustic curve according to the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section.
Preferably, reconstructing the acoustic curve of the gas-containing section of the reservoir by adopting a mirror image method comprises transversely inverting the acoustic curve of the gas-containing section of the reservoir by taking the maximum value of the absolute value of the acoustic curve of the gas-containing section of the reservoir as an axis.
Preferably, the acoustic curve of the gas-containing section of the reservoir is reconstructed by the following formula:
P＝2*|A|MAX-(-A)
wherein P is a reconstructed acoustic curve of the gas-containing section of the reservoir, A is an acoustic curve of the gas-containing section of the reservoir, | A | YMAXAnd the maximum value of the absolute value of the acoustic curve of the reservoir.
According to another aspect of the present invention, a system for predicting reservoir gas bearing is provided, the system comprising: a memory storing computer-executable instructions; a processor executing computer executable instructions in the memory to perform the steps of: analyzing the reservoir acoustic curve to obtain the value domain characteristics of the gas-containing section of the reservoir acoustic; reconstructing a reservoir gas-containing section acoustic curve based on the value domain characteristics of the reservoir gas-containing section acoustic; and performing wave impedance inversion based on the reconstructed acoustic curve of the gas-containing section of the reservoir to predict the gas-containing property of the reservoir.
Preferably, analyzing the reservoir sonic curve to obtain the value domain characteristics of the reservoir sonic gas-containing section comprises: and acquiring the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section based on the reservoir lithology analysis.
Preferably, the analyzing the reservoir acoustic curve comprises: and performing value domain analysis of acoustic lithology and value domain analysis of the acoustic gas-containing section on the reservoir acoustic curve according to the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section.
Preferably, reconstructing the acoustic curve of the gas-containing section of the reservoir by using a mirror image method comprises: and transversely inverting the acoustic curve of the gas-containing section of the reservoir by taking the maximum value of the absolute value of the acoustic curve of the gas-containing section of the reservoir as an axis.
Preferably, the acoustic curve of the gas-containing section of the reservoir is reconstructed by the following formula:
P＝2*|A|MAX-(-A)
wherein P is a reconstructed acoustic curve of the gas-containing section of the reservoir, A is an acoustic curve of the gas-containing section of the reservoir, | A | YMAXAnd the maximum value of the absolute value of the acoustic curve of the reservoir.
The invention has the beneficial effects that: according to the reservoir gas-containing property prediction method and the prediction system, under the condition that the acoustic impedance difference between the gas-containing section and the non-gas-containing section of the reservoir is not obvious, the acoustic curve of the gas-containing section is reconstructed, the acoustic value of the gas-containing section is highlighted to be different from the acoustic curve of the non-gas-containing section, and wave impedance inversion is carried out on the basis of the reconstructed gas-containing section acoustic curve, so that the gas-containing section of the reservoir is accurately distinguished, and the gas-containing section of the reservoir is simply and accurately predicted.
The present invention has other features and advantages which will be apparent from or are set forth in detail in the accompanying drawings and the following detailed description, which are incorporated herein, and which together serve to explain certain principles of the invention.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.
Fig. 1 shows a flow diagram of a reservoir gas fraction prediction method according to an embodiment of the invention.
Fig. 2 shows a sonic signature of a reservoir gas bearing prediction method according to an embodiment of the invention.
Fig. 3 illustrates a reconstructed acoustic curve of a reservoir gas fraction prediction method according to an embodiment of the invention.
Fig. 4 shows a raw acoustic curve intersection.
Fig. 5 shows a reconstructed sonic profile junction of reservoir gas sections for a reservoir gas fraction prediction method according to an embodiment of the invention.
Fig. 6 shows a wave impedance inversion profile before the reconstructed curve.
FIG. 7 illustrates a reconstructed post-acoustic-curve wave-impedance inversion profile of a reservoir gas-bearing prediction method according to an embodiment of the invention.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
The reservoir gas content prediction method comprises the following steps: analyzing the reservoir acoustic curve to obtain the value domain characteristics of the gas-containing section of the reservoir acoustic; reconstructing a reservoir gas-containing section acoustic curve based on the value domain characteristics of the reservoir gas-containing section acoustic; and performing wave impedance inversion based on the reconstructed acoustic curve of the gas-containing section of the reservoir to predict the gas-containing property of the reservoir.
Specifically, under the condition that the acoustic impedance difference between the gas-containing section and the non-gas-containing section of the reservoir is not obvious, a reservoir acoustic curve is read from the acoustic logging curve, the abscissa of the reservoir acoustic curve is an acoustic value domain representing the acoustic velocity (m/s), and the ordinate of the reservoir acoustic curve is the depth (m). The gas-containing sound wave velocity and the gas-free sound wave velocity are mixed together, the sound wave velocity range is 4000m/s-5500m/s, and the sound wave velocity range belongs to a large value range, so that the sound wave velocity range is difficult to distinguish obviously. Thus, the depth range of sandstone, the depth range of gas-containing segment, and the depth range of gas-free segment are obtained from the reservoir lithology analysis results, for example, from lithology curves. And reading corresponding acoustic velocity in the reservoir acoustic curve by combining the depth ranges of the gas-containing section and the gas-free section, namely the value range of the gas-containing section of the reservoir acoustic and the value range of the gas-free section of the acoustic. Based on the value range of the gas-free section of the acoustic wave, reconstructing the acoustic curve of the gas-containing section of the reservoir, reserving the original acoustic curve of the gas-free section, reconstructing the acoustic curve of the gas-containing section of the reservoir only, reducing the artificial participation degree brought by the reconstruction of the whole section of the curve, obviously distinguishing the gas-containing section of the reservoir from the non-gas-containing section of the reservoir by the acoustic curve after image reconstruction, acquiring a speed value, and performing acoustic impedance inversion by using the reconstructed acoustic curve of the gas-containing section of the reservoir to predict the gas content of the reservoir.
According to the illustrative reservoir gas-containing property prediction method, under the condition that the acoustic impedance difference between a gas-containing section and a non-gas-containing section of a reservoir is not obvious, a gas-containing section acoustic curve is reconstructed, the gas-containing section acoustic value is highlighted to be different from the non-gas-containing section acoustic curve, and wave impedance inversion is carried out on the basis of the reconstructed gas-containing section acoustic curve, so that the gas-containing section of the reservoir is accurately distinguished, and the gas-containing section of the reservoir is simply and accurately predicted.
As a preferred scheme, analyzing the reservoir acoustic curve, and before obtaining the value domain characteristics of the reservoir acoustic gas-containing segment, the method comprises the following steps: and acquiring the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section based on the reservoir lithology analysis.
Preferably, analyzing the reservoir sonic profile comprises: and performing value domain analysis of acoustic lithology and value domain analysis of the acoustic gas-containing section on the reservoir acoustic curve according to the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section.
Specifically, the reservoir sonic curve is subjected to sonic lithology value domain analysis and sonic gas-containing section value domain analysis, the depth range of sandstone, the depth range of gas-containing section and the depth range of gas-free section are determined through the lithology analysis, based on the depth range of sandstone, the depth range of gas-containing section and the depth range of gas-free section, the sonic velocity of sandstone, the sonic velocity of gas-containing section and the sonic velocity of gas-free section are read from the reservoir sonic curve, namely the reservoir sonic sandstone value domain, the sonic gas-containing section value domain and the sonic gas-free section value domain. And judging whether the sound wave speed is a large value, a small value or a small value in the large value by combining the value range of the gas-containing section of the sound wave.
As a preferred scheme, a mirror image method is adopted to reconstruct a gas-containing section acoustic curve of a reservoir, and the method comprises the following steps: and transversely inverting the acoustic curve of the gas-containing section of the reservoir by taking the maximum value of the absolute value of the acoustic curve of the gas-containing section of the reservoir as an axis.
As a preferred scheme, the acoustic curve of the gas-containing section of the reservoir is reconstructed by the following formula:
P＝2*|A|MAX-(-A)
wherein P is a reconstructed acoustic curve of the gas-containing section of the reservoir, A is an acoustic curve of the gas-containing section of the reservoir, | A | YMAXAnd the maximum value of the absolute value of the acoustic curve of the reservoir.
Specifically, the gas-containing section of the underground reservoir cannot be directly distinguished by using the acoustic impedance characteristics sometimes, so that inversion cannot be performed by using acoustic impedance, the acoustic curve of the gas-containing section of the reservoir is reserved and only the acoustic curve of the gas-containing section is reconstructed under the condition that the acoustic curves of the gas-containing section of the reservoir and the non-gas-containing section of the reservoir cannot be distinguished, the acoustic impedance value of the gas-containing section is highlighted, the acoustic curve of the gas-containing section of the reservoir is transversely inverted by taking the maximum value of the absolute value of the acoustic curve of the reservoir as an axis, so that a relatively low value is changed into a high value, and more than a certain threshold value in reservoir inversion is easily selected as an effective reservoir range. The reconstruction method is different from the traditional reconstruction method for reconstructing the whole acoustic curve, the characteristic of the acoustic curve of the gas-containing section is used for reconstructing the gas-containing section and performing subsequent gas-containing inversion prediction, and wave impedance inversion is performed on the basis of the reconstructed acoustic curve of the gas-containing section, so that the gas-containing section of the reservoir is accurately distinguished, and the simple and accurate prediction of the gas-containing section of the reservoir is realized.
Specifically, the maximum value of the absolute value of the acoustic curve of the reservoir is read, negative value operation is carried out on the acoustic curve of the gas-containing section of the reservoir, a reconstructed curve is obtained by subtracting the negative value operation from the double maximum value absolute value, and the formula is as follows:
P＝2*|A|MAX-(-A)
wherein P is a reconstructed acoustic curve of the gas-containing section of the reservoir, A is an acoustic curve of the gas-containing section of the reservoir, | A | YMAXAnd the maximum value of the absolute value of the acoustic curve of the reservoir.
According to another aspect of the present invention, a system for predicting reservoir gas bearing is provided, the system comprising: a memory storing computer-executable instructions; a processor executing computer executable instructions in the memory to perform the steps of: analyzing the reservoir acoustic curve to obtain the value domain characteristics of the gas-containing section of the reservoir acoustic; reconstructing a reservoir gas-containing section acoustic curve based on the value domain characteristics of the reservoir gas-containing section acoustic; and performing wave impedance inversion based on the reconstructed acoustic curve of the gas-containing section of the reservoir to predict the gas-containing property of the reservoir.
Specifically, under the condition that the acoustic impedance difference between the gas-containing section and the non-gas-containing section of the reservoir is not obvious, a reservoir acoustic curve is read from the acoustic logging curve, the abscissa of the reservoir acoustic curve is an acoustic value domain representing the acoustic velocity (m/s), and the ordinate of the reservoir acoustic curve is the depth (m). The velocity of the gas-containing sound waves and the velocity of the gas-free sound waves are mixed, the range of the sound wave velocity is 4000m/s-5500m/s, the sound wave velocity belongs to a large value range, and the sound wave velocity is difficult to distinguish obviously. Thus, the depth range of sandstone, the depth range of gas-containing segment, and the depth range of gas-free segment are obtained from the reservoir lithology analysis results, for example, from lithology curves. And reading corresponding acoustic velocity in the reservoir acoustic curve by combining the depth ranges of the gas-containing section and the gas-free section, namely the value range of the gas-containing section of the reservoir acoustic and the value range of the gas-free section of the acoustic. Based on the value range of the gas-free section of the acoustic wave, reconstructing the acoustic curve of the gas-containing section of the reservoir, reserving the original acoustic curve of the gas-free section, reconstructing the acoustic curve of the gas-containing section of the reservoir only, reducing the artificial participation degree brought by the reconstruction of the whole section of the curve, obviously distinguishing the gas-containing section of the reservoir from the non-gas-containing section of the reservoir by the acoustic curve after image reconstruction, acquiring a speed value, and performing acoustic impedance inversion by using the reconstructed acoustic curve of the gas-containing section of the reservoir to predict the gas content of the reservoir.
According to the illustrative reservoir gas-containing property prediction system, under the condition that the acoustic impedance difference between a gas-containing section and a non-gas-containing section of a reservoir is not obvious, a gas-containing section acoustic curve is reconstructed, the gas-containing section acoustic value is highlighted to be different from the non-gas-containing section acoustic curve, and wave impedance inversion is carried out on the basis of the reconstructed gas-containing section acoustic curve, so that the gas-containing section of the reservoir is accurately distinguished, and the gas-containing section of the reservoir is simply and accurately predicted.
As a preferred scheme, analyzing the reservoir acoustic curve, and before obtaining the value domain characteristics of the reservoir acoustic gas-containing segment, the method comprises the following steps: and acquiring the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section based on the reservoir lithology analysis.
Preferably, analyzing the reservoir sonic profile comprises: and performing value domain analysis of acoustic lithology and value domain analysis of the acoustic gas-containing section on the reservoir acoustic curve according to the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section.
Specifically, the reservoir sonic curve is subjected to sonic lithology value domain analysis and sonic gas-containing section value domain analysis, the depth range of sandstone, the depth range of gas-containing section and the depth range of gas-free section are determined through the lithology analysis, based on the depth range of sandstone, the depth range of gas-containing section and the depth range of gas-free section, the sonic velocity of sandstone, the sonic velocity of gas-containing section and the sonic velocity of gas-free section are read from the reservoir sonic curve, namely the reservoir sonic sandstone value domain, the sonic gas-containing section value domain and the sonic gas-free section value domain. And judging whether the sound wave speed is a large value, a small value or a small value in the large value by combining the value range of the gas-containing section of the sound wave.
As a preferred scheme, a mirror image method is adopted to reconstruct a gas-containing section acoustic curve of a reservoir, and the method comprises the following steps: and transversely inverting the acoustic curve of the gas-containing section of the reservoir by taking the maximum value of the absolute value of the acoustic curve of the reservoir as an axis.
As a preferred scheme, the acoustic curve of the gas-containing section of the reservoir is reconstructed by the following formula:
P＝2*|A|MAX-(-A)
wherein P is a reconstructed acoustic curve of the gas-containing section of the reservoir, A is an acoustic curve of the gas-containing section of the reservoir, | A | YMAXAnd the maximum value of the absolute value of the acoustic curve of the reservoir.
Specifically, the gas-containing section of the underground reservoir cannot be directly distinguished by using the acoustic impedance characteristics sometimes, so that inversion cannot be performed by using acoustic impedance, the acoustic curve of the gas-containing section of the reservoir is reserved and only the acoustic curve of the gas-containing section is reconstructed under the condition that the acoustic curves of the gas-containing section of the reservoir and the non-gas-containing section of the reservoir cannot be distinguished, the acoustic impedance value of the gas-containing section is highlighted, the acoustic curve of the gas-containing section of the reservoir is transversely inverted by taking the maximum value of the absolute value of the acoustic curve of the gas-containing section of the reservoir as an axis, so that a relatively low value is changed into a high value, and more than a certain threshold value in reservoir inversion is easily selected as an effective reservoir range. The reconstruction method is different from the traditional reconstruction method for reconstructing the whole acoustic curve, the characteristic of the acoustic curve of the gas-containing section is used for reconstructing the gas-containing section and performing subsequent gas-containing inversion prediction, and wave impedance inversion is performed on the basis of the reconstructed acoustic curve of the gas-containing section, so that the gas-containing section of the reservoir is accurately distinguished, and the simple and accurate prediction of the gas-containing section of the reservoir is realized.
Specifically, the maximum value of the absolute value of the acoustic curve of the reservoir is read, negative value operation is carried out on the acoustic curve of the gas-containing section of the reservoir, a reconstructed curve is obtained by subtracting the negative value operation from the double maximum value absolute value, and the formula is as follows:
P＝2*|A|MAX-(-A)
wherein P is a reconstructed acoustic curve of the gas-containing section of the reservoir, A is an acoustic curve of the gas-containing section of the reservoir, | A | YMAXThe maximum value of the absolute value of the reservoir acoustic curve.
Examples
Fig. 1 shows a flow diagram of a reservoir gas fraction prediction method according to an embodiment of the invention. Fig. 2 shows a sonic signature of a reservoir gas bearing prediction method according to an embodiment of the invention. Fig. 3 illustrates a reconstructed acoustic curve of a reservoir gas fraction prediction method according to an embodiment of the invention. Fig. 4 shows a raw acoustic curve intersection. Fig. 5 shows a reconstructed sonic profile intersection of reservoir gas segments for a method of reservoir gas fraction prediction according to an embodiment of the present invention. Fig. 6 shows a wave impedance inversion profile before the reconstructed curve. FIG. 7 illustrates a reconstructed post-acoustic-curve wave-impedance inversion profile of a reservoir gas-bearing prediction method according to an embodiment of the invention.
As shown in fig. 1, the method for predicting the gas content of the reservoir comprises the following steps:
s102: analyzing the reservoir acoustic curve to obtain the value domain characteristics of the gas-containing section of the reservoir acoustic;
as shown in FIG. 2, the acoustic curve of a reservoir non-gas-containing section is 4700m/s-5100m/s, the gas-containing section is 4300-5000m/s, and surrounding rocks are lower than 5000 m/s. The original acoustic curve can not be inverted by using the wave impedance characteristics of the gas-containing section in the subsequent inversion to predict the gas-containing property.
The method comprises the following steps of analyzing a reservoir acoustic curve, and obtaining value domain characteristics of a reservoir acoustic gas-containing section: and acquiring the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section based on the reservoir lithology analysis.
Wherein, according to the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section, analyzing the acoustic curve of the reservoir comprises the following steps: and performing value domain analysis of acoustic lithology and value domain analysis of acoustic gas-containing sections on the reservoir acoustic curve.
S104: reconstructing a reservoir gas-containing section acoustic curve based on the value domain characteristics of the reservoir gas-containing section acoustic;
the method for reconstructing the gas-containing section acoustic curve of the reservoir by adopting the mirror image method comprises the following steps: and transversely inverting the acoustic curve of the gas-containing section of the reservoir by taking the maximum value of the absolute value of the acoustic curve of the reservoir as an axis.
The method comprises the following steps of (1) reconstructing a gas-containing section acoustic curve of a reservoir by the following formula:
P＝2*|A|MAX-(-A)
wherein P is a reconstructed acoustic curve of the gas-containing section of the reservoir, A is an acoustic curve of the gas-containing section of the reservoir, | A | YMAXThe maximum value of the absolute value of the reservoir acoustic curve.
As shown in FIG. 3, the acoustic curve of the non-gas-containing section is unchanged after the mirror image processing, the acoustic value of the gas-containing section is within the range of 5000m/s-5300m/s, and the gas-containing range of the reservoir is easily selected to be more than 5000m/s-5300m/s in the reservoir inversion.
As shown in FIG. 4, the original sonic profile cannot distinguish gas-containing sections from non-gas-containing sections, and all reservoirs are in the range of 4300m/s to 5300 m/s. As shown in FIG. 5, the reconstructed acoustic curve contains gas segments which are clearly within the range of 4500m/s-5300m/s of the acoustic curve.
S106: and performing wave impedance inversion based on the reconstructed acoustic curve of the gas-containing section of the reservoir to predict the gas-containing property of the reservoir.
As shown in fig. 6, the a-well is a top productive well and has no significant response on the original wave impedance inversion profile.
As shown in fig. 7, the a-well is a top productive well, and the effect is obvious on the reconstructed curvilinear wave impedance inversion section. The reconstructed wave impedance curve inversion can well reflect the gas-bearing stratum of the reservoir. Experiments show that the gas content prediction coincidence rate is improved by 5% by applying the technology of the invention.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (8)
1. A method for predicting reservoir gas bearing capacity, comprising:
analyzing the reservoir acoustic curve to obtain the value domain characteristics of the gas-containing section of the reservoir acoustic;
reconstructing a reservoir gas-containing section acoustic curve based on the value domain characteristics of the reservoir gas-containing section acoustic;
performing wave impedance inversion based on the reconstructed acoustic curve of the gas-containing section of the reservoir to predict the gas-containing property of the reservoir;
reconstructing the acoustic curve of the gas-containing section of the reservoir by the following formula:
P＝2*|A|MAX-(-A)
wherein P is a reconstructed acoustic curve of the gas-containing section of the reservoir, A is an acoustic curve of the gas-containing section of the reservoir, | A | YMAXAnd the maximum value of the absolute value of the acoustic curve of the reservoir.
2. The method for predicting the gas content of the reservoir according to claim 1, wherein the step of analyzing the acoustic curve of the reservoir to obtain the value domain characteristics of the acoustic gas content section of the reservoir comprises the following steps: and acquiring the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section based on the reservoir lithology analysis.
3. A reservoir gas bearing prediction method as claimed in claim 2 wherein said analyzing a reservoir sonic profile comprises: and performing value domain analysis of acoustic lithology and value domain analysis of the acoustic gas-containing section on the reservoir acoustic curve according to the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section.
4. The method for predicting the gas content of the reservoir according to claim 1, wherein the step of reconstructing the acoustic curve of the gas-containing section of the reservoir by adopting a mirror image method comprises the following steps: and transversely inverting the acoustic curve of the gas-containing section of the reservoir by taking the maximum value of the absolute value of the acoustic curve of the reservoir as an axis.
5. A reservoir gas bearing capacity prediction system, the system comprising:
a memory storing computer-executable instructions;
a processor executing computer executable instructions in the memory to perform the steps of:
analyzing the reservoir acoustic curve to obtain the value domain characteristics of the gas-containing section of the reservoir acoustic;
reconstructing a reservoir gas-containing section acoustic curve based on the value domain characteristics of the reservoir gas-containing section acoustic;
performing wave impedance inversion based on the reconstructed acoustic curve of the gas-containing section of the reservoir to predict the gas-containing property of the reservoir;
reconstructing the acoustic curve of the gas-containing section of the reservoir by the following formula:
P＝2*|A|MAX-(-A)
wherein P is a reconstructed acoustic curve of the gas-containing section of the reservoir, A is an acoustic curve of the gas-containing section of the reservoir, | A | YMAXAnd the maximum value of the absolute value of the acoustic curve of the reservoir.
6. The reservoir gas fraction prediction system of claim 5, wherein analyzing the reservoir sonic curve to obtain the value domain characteristic of the reservoir sonic gas fraction comprises: and acquiring the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section based on the reservoir lithology analysis.
7. A reservoir gas void prediction system as defined in claim 6, wherein the analyzing the reservoir sonic profile comprises: and performing value domain analysis of acoustic lithology and value domain analysis of the acoustic gas-containing section on the reservoir acoustic curve according to the depth of the sandstone, the depth of the gas-free section and the depth of the gas-containing section.
8. A reservoir gas fraction prediction system according to claim 5, characterized in that the reconstruction of the reservoir gas fraction sonic profile using a mirroring method comprises: and transversely inverting the acoustic curve of the gas-containing section of the reservoir by taking the maximum value of the absolute value of the acoustic curve of the reservoir as an axis.
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