A quantitative evaluation method for diagenetic facies of low permeability sandstone

Abstract

The invention discloses a quantitative evaluation method for diagenetic phase of low permeability sandstone, including determining a target stratum; obtaining the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity and apparent microporosity of the target stratum; obtaining a diagenetic index; obtaining the porosity, permeability, pore type and main diagenesis of the target stratum; determining the diagenetic phase of the target stratum according to the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity, apparent microporosity, diagenetic index, porosity, permeability, pore type and main diagenesis of the target stratum; taking corresponding measures for exploration and development according to the diagenetic phase of the target stratum. The two parameters of apparent cementation rate and apparent dissolution rate are optimized to make the characterization of the influence of dissolution and cementation on the reservoir more accurate. The apparent porosity parameter is added to characterize the influence of intergranular pores on the reservoir, and finally the diagenetic index is summarized by five parameters. The result is more accurate.

Description

Technical Field

[0001] The invention belongs to the field of reservoir exploration and development, and particularly relates to a quantitative evaluation method for low-permeability sandstone diagenetic phases. Background Art

[0002] Diagenetic phase refers to the diagenesis after sediments form sedimentary rocks but before metamorphism occurs, covering research contents such as diagenetic minerals, diagenetic environment, diagenetic stage, and diagenetic evolution sequence. Diagenesis is generally divided into destructive diagenesis and constructive diagenesis. Destructive diagenesis mainly includes mechanical compaction and pressure dissolution, calcareous cementation, argillaceous cementation, siliceous cementation, etc., all of which make the reservoir performance worse. The apparent compaction rate and apparent cementation rate are used to evaluate the intensity of diagenesis. Constructive diagenesis mainly includes dissolution and micropores, which can improve or preserve better reservoir performance. The apparent dissolution rate and apparent microporosity are used to characterize the diagenetic intensity.

[0003] For low-permeability sandstone reservoirs dominated by micropores, the current diagenetic phase evaluation index cannot fully and objectively reflect the impact of diagenesis on the reservoir. In the present invention, we optimize the two parameters of apparent cementation rate and apparent dissolution rate to make the characterization of the impact of dissolution and cementation on the reservoir more accurate. And add the apparent porosity parameter to characterize the impact of intergranular pores on the reservoir, and finally summarize the diagenetic index with five parameters. Summary of the invention

[0004] The purpose of the present invention is to provide a quantitative evaluation method for low permeability sandstone diagenetic phase, so as to characterize the influence of dissolution and cementation on the reservoir more accurately, and to add the apparent porosity parameter to characterize the influence of intergranular pores on the reservoir.

[0005] The object of the present invention is achieved by the following technical means: a quantitative evaluation method for low permeability sandstone diagenetic phase, comprising:

[0006] Determine the target formation;

[0007] Obtain the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity and apparent microporosity of the target stratum;

[0008] Obtaining diagenetic index;

[0009] Obtain the porosity, permeability, pore type and main diagenesis of the target formation;

[0010] Determine the diagenetic phase of the target formation based on the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity, apparent microporosity, diagenetic index, porosity, permeability, pore type and main diagenesis of the target formation;

[0011] Take corresponding measures for exploration and development according to the diagenetic phase of the target stratum.

[0012] Said

[0013] The original pore volume is: φ = 20.91 + (22.9 / So), and the parameter So is the Trask sorting system. Q1: The particle diameter corresponding to 25% on the particle size accumulation curve (mm); Q3: The particle diameter corresponding to 75% on the particle size accumulation curve;

[0014] Intergranular volume after compaction: intergranular pore volume and cement volume in rock cast thin sections.

[0015] Said

[0016] The cement volume is the content of cement in the rock casting thin section,

[0017] Original pore volume: φ = 20.91 + (22.9 / So), parameter So is the Trask sorting system, Q1: The particle diameter (mm) corresponding to 25% on the cumulative particle size curve; Q3: The particle diameter (mm) corresponding to 75% on the cumulative particle size curve.

[0018] Said In the formula, the dissolution surface ratio is the surface ratio of the dissolution pores in the rock casting thin section; porosity is the physical porosity of the rock.

[0019] Said

[0020] The intergranular pores in the formula are the surface ratio of the intergranular pores in the rock casting thin section.

[0021] Original pore volume: φ = 20.91 + (22.9 / So), parameter So is the Trask sorting system, Q1: The particle diameter corresponding to 25% on the cumulative particle size curve; Q3: The particle diameter corresponding to 75% on the cumulative particle size curve.

[0022] Said Where: surface porosity is the sum of surface porosities in rock casting thin sections, and porosity is the physical porosity of the rock.

[0023] Said

[0024] The specific method for determining the diagenetic phase of the target formation according to the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity, apparent microporosity, diagenetic index, porosity, permeability, pore type and main diagenesis of the target formation is:

[0025] Determine the classification thresholds, including:

[0026] Regarding the compaction rate \(a\), if \(a > 70\%\), the compaction degree is strong; if \(30\% < a < 70\%\), the compaction degree is medium; if \(a < 30\%\), the compaction strength is weak;

[0027] Regarding the cementation rate \(b\), if \(b > 70\%\), the cementation degree is strong; if \(30\% < b < 70\%\), the cementation degree is medium; if \(b < 30\%\), the cementation strength is relatively weak;

[0028] Regarding the dissolution rate \(c\), if \(c < 5\%\), the dissolution is weak; if \(5\% < c < 15\%\), the dissolution is medium; if \(c > 15\%\), the dissolution is strong;

[0029] Regarding the porosity \(d\), if \(d < 5\%\), the degree is low; if \(5\% < d < 15\%\), the degree is medium; if \(d > 15\%\), the degree is high;

[0030] Regarding the microporosity \(e\), if \(e < 30\%\), the microporosity is low; if \(30\% < e < 70\%\), it is medium; if \(e > 70\%\), the microporosity is high;

[0031] Regarding the diagenetic index \(Di\), if \(Di < 5\), the degree is low; if \(5 < Di < 15\), it is medium; if \(Di > 15\), the degree is high;

[0032] The quantitative classification of diagenetic facies includes:

[0033] Weak cementation intergranular pore facies, simultaneously satisfying \(12\leqslant\) porosity \(\leqslant20\), \(1\leqslant\) permeability \(\leqslant100\), the pore type belongs to intergranular pores, the main diagenetic process is compaction, \(40\leqslant\) compaction rate \(\leqslant50\), \(20\leqslant\) cementation rate \(\leqslant40\), \(1\leqslant\) dissolution rate \(\leqslant10\), \(10\leqslant\) porosity \(\leqslant15\), \(40\leqslant\) microporosity \(\leqslant50\), diagenetic index \(< 5\);

[0034] Chlorite cementation intergranular pore facies, simultaneously satisfying \(12\leqslant\) porosity \(\leqslant17\), \(1\leqslant\) permeability \(\leqslant10\), the pore type belongs to intergranular pores, the main diagenetic process is cementation, \(50\leqslant\) compaction rate \(\leqslant60\), \(25\leqslant\) cementation rate \(\leqslant35\), \(5\leqslant\) dissolution rate \(\leqslant15\), \(8\leqslant\) porosity \(\leqslant12\), \(40\leqslant\) microporosity \(\leqslant50\), diagenetic index \(< 5\);

[0035] Medium compaction strong dissolution facies, simultaneously satisfying \(8\leqslant\) porosity \(\leqslant15\), \(0.3\leqslant\) permeability \(\leqslant3\), the pore type belongs to dissolved pores, the main diagenetic process is dissolution, \(50\leqslant\) compaction rate \(\leqslant70\), \(20\leqslant\) cementation rate \(\leqslant40\), \(15\leqslant\) dissolution rate \(\leqslant35\), \(1\leqslant\) porosity \(\leqslant8\), \(50\leqslant\) microporosity \(\leqslant60\), diagenetic index \(< 5\);

[0036] Medium compaction micropore dissolution facies, simultaneously satisfying \(7\leqslant\) porosity \(\leqslant12\), \(0.1\leqslant\) permeability \(\leqslant0.5\), the pore type belongs to micropore - dissolved pores, the main diagenetic process is dissolution, \(40\leqslant\) compaction rate \(\leqslant50\), \(40\leqslant\) cementation rate \(\leqslant50\), \(1\leqslant\) dissolution rate \(\leqslant5\), \(1\leqslant\) porosity \(\leqslant5\), \(80\leqslant\) microporosity \(\leqslant90\), \(5\leqslant\) diagenetic index \(\leqslant15\);

[0037] Medium compacted microporous phase, at the same time, meets the following conditions: 7≤porosity≤10, 0.1≤permeability≤0.5, pore type belongs to solution pore-micropore, main diagenesis is dissolution, 50≤apparent compaction rate≤70, 40≤apparent cementation rate≤50, 1≤apparent dissolution rate≤5, 1≤apparent porosity≤5, 80≤apparent microporosity≤90, 5≤diagenetic index≤15;

[0038] Strongly compacted dense phase, at the same time, meets the following conditions: 2≤porosity≤8, permeability<0.1, pore type belongs to micropores, the main diagenesis is compaction, apparent compaction ratio>60, 30≤apparent cementation ratio≤50, apparent dissolution ratio<1, apparent porosity<1, apparent microporosity>90, 15≤diagenetic index≤35;

[0039] Strongly cemented dense phase, at the same time, meets the following conditions: 2≤porosity≤8, permeability<0.1, pore type belongs to cementation, main diagenesis is compaction, 50≤apparent compaction≤60, apparent cementation>60, apparent dissolution<1, apparent porosity<1, apparent microporosity>90, 15≤diagenetic index≤35;

[0040] Medium compaction and medium cementation dense phase, at the same time, meets the following conditions: 2≤porosity≤8, permeability<0.1, pore type belongs to micropore, the main diagenesis is compaction, 50≤apparent compaction rate≤70, 40≤apparent cementation rate≤60, apparent dissolution rate<1, apparent porosity<1, apparent microporosity>90, 15≤diagenetic index≤35.

[0041] The beneficial effects of the present invention are as follows: the two parameters of apparent cementation rate and apparent dissolution rate are optimized, so that the influence of dissolution and cementation on the reservoir is more accurately characterized. The apparent porosity parameter is added to characterize the influence of intergranular pores on the reservoir, and finally the diagenetic index is summarized by five parameters. The result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a comparison chart of the apparent cementation rate and cementing material content;

[0043] Figure 2 This is a comparison chart of the visual dissolution rate and the dissolution surface rate;

[0044] Figure 3 is the correlation diagram between the surface ratio content and the diagenetic index;

[0045] Figure 4 is the correlation diagram between intergranular pore content and diagenetic index;

[0046] Figure 5 is the correlation diagram between porosity and diagenetic index;

[0047] Figure 6 is the correlation diagram between permeability and diagenetic index;

[0048] Figure 7 It is a comprehensive evaluation standard for diagenetic facies;

[0049] Figure 8 is the apparent compaction rate histogram;

[0050] Fig. 9 is the frequency distribution histogram of apparent compaction rate;

[0051] Fig.10 is the histogram of apparent cementation rate;

[0052] Fig.11 is the frequency distribution histogram of apparent cementation rate;

[0053] Fig.12 Apparent dissolution rate histogram

[0054] Fig.13 is the frequency distribution histogram of the apparent dissolution rate

[0055] Fig.14 is the apparent porosity histogram;

[0056] Fig.15 is the apparent porosity frequency distribution histogram;

[0057] Fig.16 is the apparent microporosity histogram;

[0058] Fig.17 is the frequency distribution histogram of apparent microporosity;

[0059] Fig.18 is the diagenetic index histogram;

[0060] Fig.19 It is the frequency distribution histogram of diagenetic index.

[0061] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0062] [Example 1]

[0063] A quantitative evaluation method for low permeability sandstone diagenetic phases, including

[0064] Determine the target formation;

[0065] Obtain the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity and apparent microporosity of the target stratum;

[0066] Obtaining diagenetic index;

[0067] Obtain the porosity, permeability, pore type and main diagenesis of the target formation;

[0068] Determine the diagenetic phase of the target formation based on the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity, apparent microporosity, diagenetic index, porosity, permeability, pore type and main diagenesis of the target formation;

[0069] By extracting experimental analysis data such as casting thin sections, image particle size, and reservoir rock properties, the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity, and apparent microporosity are calculated, and the diagenetic index formula is derived.

[0070] Take corresponding measures for exploration and development according to the diagenetic phase of the target stratum.

[0071] Said

[0072] The original pore volume is: φ = 20.91 + (22.9 / So), and the parameter So is the Trask sorting system. Q1: The particle diameter corresponding to 25% on the cumulative particle size curve (mm); Q3: The particle diameter corresponding to 75% on the cumulative particle size curve (mm);

[0073] Intergranular volume after compaction: intergranular pore volume and cement volume in rock cast thin sections.

[0074] Visual compaction rate evaluation is used to characterize the intensity of the impact of compaction on reservoir performance through quantitative calculation of rock casting thin sections and image particle size data.

[0075] Said

[0076] The cement volume is the content of cement in the rock casting thin section,

[0077] Original pore volume: φ = 20.91 + (22.9 / So), parameter So is the Trask sorting system, Q1: The particle diameter (mm) corresponding to 25% on the cumulative particle size curve; Q3: The particle diameter (mm) corresponding to 75% on the cumulative particle size curve.

[0078] The current formula for calculating the apparent cementation rate is:

[0079] The calculation formula of this apparent cementation rate is:

[0080] When the original porosity value is introduced to replace the currently commonly used intergranular volume value in the calculation of the apparent cementation rate, the correlation between the cement content and the apparent cementation rate is greatly improved. Figure 1 This shows that this parameter can better reflect the degree of diagenesis.

[0081] Visual cementation evaluation is used to characterize the intensity of the impact of cementation on reservoir performance through quantitative calculation of rock casting thin sections and image grain size data.

[0082] Said In the formula, the dissolution surface ratio is the surface ratio of the dissolution pores in the rock casting thin section; porosity is the physical porosity of the rock.

[0083] The current calculation formula for apparent dissolution rate is:

[0084]

[0085] The calculation formula of this apparent dissolution rate is:

[0086]

[0087] like Figure 2 As shown, Figure 2 (a) is a correlation diagram between the apparent dissolution rate and the dissolution surface ratio calculated based on the currently commonly used apparent dissolution rate formula. It can be seen that the dissolution pores and the dissolution rate are positively correlated overall. However, if the reservoir only has dissolution pores as a single pore, the dissolution rate reaches 100%, exaggerating the impact of dissolution on the reservoir. This time, the reference to porosity participation in the calculation can solve this defect. Figure 2 (b) shows that the correlation between the two is very good.

[0088] Visual dissolution rate evaluation is used to characterize the impact of dissolution on reservoir performance through quantitative calculation of rock casting thin sections and physical property data.

[0089] Said

[0090] The intergranular pores in the formula are the surface ratio of the intergranular pores in the rock casting thin section.

[0091] Original pore volume: φ = 20.91 + (22.9 / So), parameter So is the Trask sorting system, Q1: The particle diameter (mm) corresponding to 25% on the cumulative particle size curve; Q3: The particle diameter (mm) corresponding to 75% on the cumulative particle size curve.

[0092] Apparent porosity evaluation is quantitatively calculated through rock casting thin sections and image grain size data to characterize the intensity of the impact of residual intergranular pores on reservoir performance.

[0093] Said Where: surface porosity is the sum of surface porosities in rock casting thin sections, and porosity is the physical porosity of the rock.

[0094] Visual microporosity evaluation is a content parameter used to characterize the content of tiny pores (pore diameter less than 0.5 μm) that are difficult to flow through in the reservoir, which is quantitatively calculated through thin sections of rock castings and physical property data.

[0095] The

[0096] A new diagenetic index evaluation formula is proposed based on comprehensive diagenetic parameters, with the visual compaction rate, visual cementation rate, and visual microporosity that have a bad influence on the reservoir as the numerator, and the visual dissolution rate, visual porosity, and porosity that have a good influence as the denominator. The lower the index, the lower the degree of diagenesis, indicating that the diagenetic processes favorable for pore preservation and formation are dominant.

[0097] The diagenetic index has a good correlation with the content of pore face ratio, intergranular pore content, porosity, and permeability value ( Figures 3 to 6 ), that is, the smaller the diagenetic index, the better the reservoir storage performance, indicating that this evaluation method can be well applied to the quantitative evaluation of diagenetic facies in low-permeability sandstone reservoirs.

[0098] Diagenetic index evaluation is a comprehensive quantitative parameter for studying and identifying the changes in reservoir storage space caused by diagenetic processes. The lower the index, the lower the degree of diagenesis, indicating that the diagenetic processes favorable for pore preservation and formation are dominant.

[0099] The specific method for determining the diagenetic facies of the target formation based on the visual compaction rate, visual cementation rate, visual dissolution rate, visual porosity, visual microporosity, diagenetic index, porosity, permeability, pore type, and main diagenetic processes of the target formation is as follows:

[0100] Define the classification thresholds, including:

[0101] Visual compaction rate a, when a > 70%, the compaction degree is strong; when 30% < a < 70%, the compaction degree is medium; when a < 30%, the compaction strength is weak;

[0102] Visual cementation rate b, when b > 70%, the cementation degree is strong; when 30% < b < 70%, the cementation degree is medium; when b < 30%, the cementation strength is weak;

[0103] Visual dissolution rate c, when c < 5%, weak dissolution; when 5% < c < 15%, medium dissolution; when c > 15%, strong dissolution;

[0104] Visual porosity d, when d < 5%, the degree is low; when 5% < d < 15%, the degree is medium; when d > 15%, the degree is high;

[0105] Visual microporosity e, when e < 30%, low microporosity; when 30% < e < 70%, medium; when e > 70%, high microporosity;

[0106] Diagenetic index Di, when Di < 5, the degree is low; when 5 < Di < 15, medium; when Di > 15, the degree is high;

[0107] The quantitative classification of diagenetic facies includes:

[0108] Weakly cemented intergranular pore phase, at the same time, meets the following conditions: 12≤porosity≤20, 1≤permeability≤100, pore type belongs to intergranular pore, main diagenesis is compaction, 40≤apparent compaction rate≤50, 20≤apparent cementation rate≤40, 1≤apparent dissolution rate≤10, 10≤apparent porosity≤15, 40≤apparent microporosity≤50, diagenetic index<5;

[0109] Chlorite cemented intergranular pore phase, at the same time, meets the following conditions: 12≤porosity≤17, 1≤permeability≤10, the pore type belongs to intergranular pores, the main diagenesis is cementation, 50≤apparent compaction rate≤60, 25≤apparent cementation rate≤35, 5≤apparent dissolution rate≤15, 8≤apparent porosity≤12, 40≤apparent microporosity≤50, diagenetic index<5;

[0110] Moderately compacted strong dissolution phase, at the same time, meets the following conditions: 8≤porosity≤15, 0.3≤permeability≤3, pore type belongs to solution pore, main diagenesis is dissolution, 50≤apparent compaction rate≤70, 20≤apparent cementation rate≤40, 15≤apparent dissolution rate≤35, 1≤apparent porosity≤8, 50≤apparent microporosity≤60, diagenetic index<5;

[0111] Medium compacted microporous dissolution phase, which satisfies the following conditions: 7≤porosity≤12, 0.1≤permeability≤0.5, the pore type belongs to micropore-dissolution pore, the main diagenesis is dissolution, 40≤apparent compaction rate≤50, 40≤apparent cementation rate≤50, 1≤apparent dissolution rate≤5, 1≤apparent porosity≤5, 80≤apparent microporosity≤90, 5≤diagenetic index≤15;

[0112] Medium compacted microporous phase, at the same time, meets the following conditions: 7≤porosity≤10, 0.1≤permeability≤0.5, pore type belongs to solution pore-micropore, main diagenesis is dissolution, 50≤apparent compaction rate≤70, 40≤apparent cementation rate≤50, 1≤apparent dissolution rate≤5, 1≤apparent porosity≤5, 80≤apparent microporosity≤90, 5≤diagenetic index≤15;

[0113] Strongly compacted dense phase, at the same time, meets the following conditions: 2≤porosity≤8, permeability<0.1, pore type belongs to micropores, the main diagenesis is compaction, apparent compaction ratio>60, 30≤apparent cementation ratio≤50, apparent dissolution ratio<1, apparent porosity<1, apparent microporosity>90, 15≤diagenetic index≤35;

[0114] Strongly cemented dense phase, at the same time, meets the following conditions: 2≤porosity≤8, permeability<0.1, pore type belongs to cementation, main diagenesis is compaction, 50≤apparent compaction≤60, apparent cementation>60, apparent dissolution<1, apparent porosity<1, apparent microporosity>90, 15≤diagenetic index≤35;

[0115] Medium compaction and medium cementation dense phase, at the same time, meets the following conditions: 2≤porosity≤8, permeability<0.1, pore type belongs to micropore, the main diagenesis is compaction, 50≤apparent compaction rate≤70, 40≤apparent cementation rate≤60, apparent dissolution rate<1, apparent porosity<1, apparent microporosity>90, 15≤diagenetic index≤35.

[0116] like Figure 7 As shown in Figure 2, the comprehensive evaluation standard of diagenetic facies is shown in Figure 2.

[0117] [Example 2]

[0118] On the basis of Example 1, the reservoirs of Chang 1 to Chang 9 in the Jiyuan area were evaluated. The study showed that the diagenesis in the Jiyuan area was mainly characterized by medium compaction, medium to weak cementation, medium dissolution, high microporosity, and medium diagenesis. The upper combination of the Yanchang Formation and Chang 9 were relatively low in the vertical direction, and the reservoir properties were good.

[0119] (1) Visual compaction rate

[0120] Figure 8 and Fig. 9 As shown in the figure, the average apparent compaction rate in Jiyuan area is 60.1%, mainly between 48.1% and 62.3%, and the strength is mainly medium compaction. Among them, the apparent compaction rate of Chang 3 and Chang 6 is relatively large, mainly due to the fine particle size, high content of flaky rock debris, etc., and the compaction resistance is relatively poor.

[0121] (2) Visual cementation rate

[0122] like Fig.10 and Fig.11 As shown in the figure, the average apparent cementation rate in Jiyuan area is 32.7%, mainly ranging from 27.2% to 44.0%, with medium to weak cementation as the main feature. Among them, Chang 1, Chang 4+5, and Chang 7 have stronger cementation, Chang 6, Chang 8, and Chang 9 have medium to weak cementation, and Chang 2 and Chang 3 have weaker cementation.

[0123] (3) Visual dissolution rate

[0124] like Fig.12 and 13 The average apparent dissolution rate in the Jiyuan area is 12.3%, mainly between 8.7% and 13.4%, with medium dissolution being the main factor. The contribution of the upper Yanchang combination and the secondary pores of Chang 9 is large, while the rest are relatively low.

[0125] (4) Apparent porosity

[0126] like Fig.14 and 15 The apparent porosity in the Jiyuan area shown varies greatly, with an average of 7.8%, mainly ranging from 2.69% to 11.78%. On the whole, the intergranular pores are developed to a medium to low degree. The intergranular pores in Chang 9 and the upper combination are remnant, and the intergranular pores in Chang 7 are the least.

[0127] (5) Microporosity

[0128] like Fig.16 and 17 As shown, the average apparent microporosity in Jiyuan area is 67.4%, mainly ranging from 51.1% to 82.1%, with medium to high microporosity being the main one. The microporosity in Chang 4+5 to Chang 7 is high, about 80%.

[0129] (6) Diagenetic index

[0130] like Fig.18 and 19 As shown in the figure, the average diagenetic index of the Jiyuan area is 7.1, mainly ranging from 3.8 to 11.9, with low to medium diagenetic degree as the main feature. The upper assemblage has a low diagenetic degree and good reservoir properties, while Chang 4+5 and Chang 7 have a high diagenetic degree and poor reservoir properties.

[0131] From the above, it can be seen that the evaluation method is applied to the evaluation of diagenesis in the Jiyuan area, showing that the main characteristics of this area are medium compaction, medium-weak cementation, medium dissolution, high microporosity, and medium diagenesis. In the vertical direction, the diagenetic index of the extended groups Chang 1, Chang 2, Chang 3 and Chang 9 is low, and the reservoir is good. This is consistent with the research results, and further confirms that the diagenetic phase evaluated by the present invention is consistent with the actual geological characteristics.

Claims

1. A method for quantitative evaluation of low permeability sandstone diagenetic phase, characterized by: Including determining the target formation; Obtaining the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity, and apparent microporosity of the target formation; Obtaining the diagenetic index; Obtaining the porosity, permeability, pore type, and main diagenetic processes of the target formation; Determining the diagenetic facies of the target formation based on the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity, apparent microporosity, diagenetic index, porosity, permeability, pore type, and main diagenetic processes of the target formation; Taking corresponding measures for exploration and development according to the diagenetic facies of the target formation; Said 2. A method for quantitatively evaluating diagenetic phases of low permeability sandstone according to claim 1, characterized in that: Said The original pore volume is: φ = 20.91 + (22.9 / So), and the parameter So is the Trask sorting system. Q1: The particle diameter corresponding to 25% on the particle size accumulation curve; Q3: The particle diameter corresponding to 75% on the cumulative grain size curve; Intergranular volume after compaction: The intergranular pore volume and cement volume in the thin section of the rock cast.

3. A method for quantitatively evaluating diagenetic facies of low permeability sandstone according to claim 1, characterized in that: Said The cement volume is the content of cement in the rock casting thin section, Original pore volume: φ = 20.91 + (22.9 / So), parameter So is the Trask sorting system, Q1: The particle diameter corresponding to 25% on the particle size accumulation curve; Q3: The particle diameter corresponding to 75% on the cumulative grain size curve.

4. A method for quantitatively evaluating diagenetic phases of low permeability sandstone according to claim 1, characterized in that: Said In the formula, the dissolution surface ratio is the surface ratio of the dissolution pores in the rock casting thin section; porosity is the physical porosity of the rock.

5. A method for quantitatively evaluating diagenetic facies of low permeability sandstone according to claim 1, characterized in that: Said The intergranular pores in the formula are the surface ratio of the intergranular pores in the rock casting thin section. Original pore volume: φ = 20.91 + (22.9 / So), parameter So is the Trask sorting system, Q1: The particle diameter corresponding to 25% on the particle size accumulation curve; Q3: The particle diameter corresponding to 75% on the cumulative grain size curve.

6. A method for quantitatively evaluating diagenetic facies of low permeability sandstone according to claim 1, characterized in that: Said Where: surface porosity is the sum of surface porosities in rock casting thin sections, and porosity is the physical porosity of the rock.

7. A method for quantitatively evaluating diagenetic facies of low permeability sandstone according to claim 1, characterized in that: The specific method for determining the diagenetic facies of the target formation based on the apparent compaction rate, apparent cementation rate, apparent dissolution rate, apparent porosity, apparent microporosity, diagenetic index, porosity, permeability, pore type, and main diagenetic processes of the target formation is as follows: Defining classification thresholds, including: Apparent compaction rate a, where a > 70%, strong compaction degree; 30% < a < 70%, medium compaction degree; a < 30%, weak compaction intensity; Apparent cementation rate b, where b > 70%, strong cementation degree; 30% < b < 70%, medium cementation degree; b < 30%, weak cementation intensity; Apparent dissolution rate c, where c < 5%, weak dissolution; 5% < c < 15%, medium dissolution; c > 15%, strong dissolution; Apparent porosity d, where d < 5%, low degree; 5% < d < 15%, medium degree; d > 15%, high degree; Apparent microporosity e, where e < 30%, low microporosity; 30% < e < 70%, medium; e > 70%, high microporosity; Diagenetic index Di, where Di < 5, low degree, 5 < Di < 15, medium, Di > 15, high degree; Quantitative classification of diagenetic facies includes: Weakly cemented intergranular pore facies, simultaneously satisfying 12 ≤ porosity ≤ 20, 1 ≤ permeability ≤ 100, pore type belonging to intergranular pores, main diagenetic process being compaction, 40 ≤ apparent compaction rate ≤ 50, 20 ≤ apparent cementation rate ≤ 40, 1 ≤ apparent dissolution rate ≤ 10, 10 ≤ apparent porosity ≤ 15, 40 ≤ apparent microporosity ≤ 50, diagenetic index < 5; Chlorite-cemented intergranular pore facies, simultaneously satisfying 12 ≤ porosity ≤ 17, 1 ≤ permeability ≤ 10, pore type belonging to intergranular pores, main diagenetic process being cementation, 50 ≤ apparent compaction rate ≤ 60, 25 ≤ apparent cementation rate ≤ 35, 5 ≤ apparent dissolution rate ≤ 15, 8 ≤ apparent porosity ≤ 12, 40 ≤ apparent microporosity ≤ 50, diagenetic index < 5; Medium-compacted and strongly dissolved facies, simultaneously satisfying 8 ≤ porosity ≤ 15, 0.3 ≤ permeability ≤ 3, pore type belonging to dissolved pores, main diagenetic process being dissolution, 50 ≤ apparent compaction rate ≤ 70, 20 ≤ apparent cementation rate ≤ 40, 15 ≤ apparent dissolution rate ≤ 35, 1 ≤ apparent porosity ≤ 8, 50 ≤ apparent microporosity ≤ 60, diagenetic index < 5; Medium compacted microporous dissolution phase, which satisfies the following conditions: 7≤porosity≤12, 0.1≤permeability≤0.5, the pore type belongs to micropore-dissolution pore, the main diagenesis is dissolution, 40≤apparent compaction rate≤50, 40≤apparent cementation rate≤50, 1≤apparent dissolution rate≤5, 1≤apparent porosity≤5, 80≤apparent microporosity≤90, 5≤diagenetic index≤15; Medium compacted microporous phase, at the same time, meets the following conditions: 7≤porosity≤10, 0.1≤permeability≤0.5, pore type belongs to solution pore-micropore, main diagenesis is dissolution, 50≤apparent compaction rate≤70, 40≤apparent cementation rate≤50, 1≤apparent dissolution rate≤5, 1≤apparent porosity≤5, 80≤apparent microporosity≤90, 5≤diagenetic index≤15; Strongly compacted dense phase, at the same time, meets the following conditions: 2≤porosity≤8, permeability<0.1, pore type belongs to micropores, the main diagenesis is compaction, apparent compaction ratio>60, 30≤apparent cementation ratio≤50, apparent dissolution ratio<1, apparent porosity<1, apparent microporosity>90, 15≤diagenetic index≤35; Strongly cemented dense phase, at the same time, meets the following conditions: 2≤porosity≤8, permeability<0.1, pore type belongs to cementation, main diagenesis is compaction, 50≤apparent compaction≤60, apparent cementation>60, apparent dissolution<1, apparent porosity<1, apparent microporosity>90, 15≤diagenetic index≤35; Medium compaction and medium cementation dense phase, at the same time, meets the following conditions: 2≤porosity≤8, permeability<0.1, pore type belongs to micropore, the main diagenesis is compaction, 50≤apparent compaction rate≤70, 40≤apparent cementation rate≤60, apparent dissolution rate<1, apparent porosity<1, apparent microporosity>90, 15≤diagenetic index≤35.

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