阅读说明：本技术 一种用于多夹层盐穴储气库造腔期夹层垮塌的判别方法 (Method for judging interlayer collapse during cavity construction period of multi-interlayer salt cavern gas storage ) 是由 张蕾 王振兴 陈晓源 于 2019-10-29 设计创作，主要内容包括：本发明提出一种用于多夹层盐穴储气库造腔期夹层垮塌的判别方法,单井岩心进行地质评价,分析岩性并进行岩心水溶实验,将目的岩层内的盐层、夹层按厚度值、岩性进行地质层位划分,计算每个层位的水溶物矿物离子SO<Sub>4</Sub><Sup>2-</Sup>总含量,层内每小层的水溶物矿物离子SO<Sub>4</Sub><Sup>2-</Sup>含量按对应小层厚度加权求和,依据SO<Sub>4</Sub><Sup>2-</Sup>总含量绘制曲线,得到其离子总量在不同层位的波动变化规律,依据溶腔回卤Na<Sub>2</Sub>SO<Sub>4</Sub>浓度日度数据绘制曲线,得到其随时间变化规律,获得回卤卤水Na<Sub>2</Sub>SO<Sub>4</Sub>浓度变化与夹层对应曲线,可判断不同夹层垮塌状况,本发明实现了地质工程一体化直观判别,可判别各个夹层的垮塌过程,垮塌初期即可及时规避夹层垮塌对管柱和溶腔的不利影响。(The invention provides a method for judging interlayer collapse in a cavity-making period of a multi-interlayer salt cavern gas storage 4 2‑ Total content, water soluble mineral ions SO per sublayer in the layer 4 2‑ The contents are weighted and summed according to the thickness of the corresponding small layer according to SO 4 2‑ Drawing a curve of the total content to obtain the fluctuation change rule of the total ion content at different layers according to the cavity brine-returning Na 2 SO 4 Drawing a curve according to the daily concentration data to obtain the time-varying rule of the concentration data, and obtaining the bittern Na 2 SO 4 The concentration change and the corresponding curve of the interlayer can judge the collapse conditions of different interlayers, and the invention realizes the integrated visual judgment of geological engineeringIn addition, the collapse process of each interlayer can be judged, and the adverse effects of interlayer collapse on the tubular column and the dissolving cavity can be avoided in time at the initial collapse stage.)

1. A method for judging interlayer collapse in the cavity-making period of a multi-interlayer salt cavern gas storage is characterized by comprising the following steps of:

s1) taking a single-well core for geological evaluation;

s2) carrying out geological horizon division on a salt layer and an interlayer in the target rock stratum according to the thickness value and lithology;

s3) the different layers are sequenced according to the depth, and the water soluble mineral ions SO of each layer are calculated₄ ^2-The total content;

s4) SO per horizon₄ ^2-Drawing a fluctuation change curve of the total content;

s5) based on cavity-dissolving back-halogenating Na₂SO₄The daily data of the concentration is used for drawing a time-varying curve;

s6) adding SO₄ ^2-Drawing a fluctuation curve and Na by total content₂SO₄Marking the concentration change curve correspondingly to judge the collapse condition of the interlayer。

2. The method for discriminating interlayer collapse during the cavity-making period of the multi-interlayer salt cavern gas storage according to claim 1, wherein the geological evaluation in the step S1) comprises the following steps: and analyzing lithology and carrying out a core water-soluble experiment to obtain the composition of rock components of each stratum of the target rock stratum and the composition data of the content of water-soluble mineral ions.

3. The method for discriminating interlayer collapse during cavity-making period of multi-interlayer salt cavern gas storage as claimed in claim 1 or 2, wherein the SO in step S3)₄ ^2-The total content is calculated by water soluble mineral ions SO in each small layer in the layer₄ ^2-The contents are weighted and summed according to the thickness of the corresponding small layer.

4. The method as claimed in claim 3, wherein the abscissa of the fluctuation curve in the step S4) is the horizon and the ordinate is the corresponding SO₄ ^2-The total content is obtained, the fluctuation change rule of the total ion content at different layers is obtained, and the peak point a is marked₁...a_nValley point b₁...b_nN is the number of layers and the peak point is SO corresponding to the salt layer₄ ^2-Total content, valley point is SO corresponding to interlayer₄ ^2-And (4) the total content.

5. The method as claimed in claim 4, wherein the curve of time variation in step S5) has an abscissa of time and an ordinate of Na for cavity-returning brine in the cavity of the multi-layered salt cavern gas storage₂SO₄The concentration is obtained, the time variation rule is obtained, and the peak point A is marked₁...A_nValley point B₁...B_n。

6. The method as claimed in claim 5, wherein the method for discriminating interlayer collapse during the cavity-making period of the multi-interlayer salt cavern gas storage is characterized in thatStep S6) includes the following: the peak point a₁...a_nAnd valley point b₁...b_nAre respectively reacted with A₁...A_nAnd B₁...B_nCorresponding mark, from a₁...a_nAnd b₁...b_nDetermining whether the corresponding horizon is a salt or an interlayer, from A₁...A_nAnd B₁...B_nAnd judging whether the corresponding interlayer collapses or not.

Technical Field

The invention belongs to the technical field of cavity construction of salt cavern underground gas storage, and particularly relates to a method for judging interlayer collapse in the cavity construction period of a multi-interlayer salt cavern gas storage.

Background

With the contradiction between the continuously and highly increased consumption of natural gas and the insufficient storage capacity of the gas storage in China, the country accelerates the promotion of the construction strength of the gas storage. Wherein the multi-interlayer salt cavern type gas storage is mainly distributed in Jianghan continental facies sedimentary basin, and the distribution area of the salt rock in the basin is as wide as 1800km². The single well target layer contains 4-7 layers of interlayers, and interlayer collapse has great influence on the stress limit of the underground pipe column and the regular dissolving and dripping of the dissolving cavity form. Whether the interlayer collapses or not is judged in time, and effective measures are taken to avoid engineering risks caused by the collapse of the interlayer, so that the method has great significance for the safe and stable dissolved cavity of the gas storage.

The method for judging interlayer collapse in the cavity-making period of the multi-interlayer salt cavern gas storage by water dissolution mainly comprises an on-site sonar cavity-measuring method and an indoor numerical simulation method, and the defects of the two methods mainly comprise the following aspects:

(1) the field method mainly depends on real-time monitoring, one method is that the sonar cavity measuring technology can visually test and judge the collapse of the interlayer, but the operation construction period is long and the cost is high. One method is to monitor the abnormal change points such as the brine return amount and the water injection pressure and judge, but is greatly influenced by environmental factors and artificial measurement errors, and the judgment accuracy is low.

(2) Based on the traditional mechanism research and analysis of the Mohr-Coulomb strength criterion, the maximum tensile stress criterion and the critical stress instability criterion, the method only aims at the single stress state of the interlayer and inconsistent incentive recognition respectively, does not consider the dynamic continuous change of the stress field of the interlayer, and has large difference of the judgment results of the three criteria.

(3) Based on numerical simulation calculation of three-dimensional rapid Lagrange analysis software FLAC3D, the interlayer is regarded as a symmetrical circular plate geometric form, and only the probability of interlayer collapse can be analyzed through calculation of parameters such as the plastic region range of the interlayer, the radial displacement and the axial displacement of the interlayer and the like, and whether the interlayer collapses cannot be accurately judged.

(4) The two methods have poor applicability in engineering application, and the analysis result has large error with field practice, so that the two methods have no good engineering guidance significance.

Disclosure of Invention

The invention aims to solve the technical problems and provides a method for judging interlayer collapse in the cavity-making period of a multi-interlayer salt cavern gas storage, which can visually judge the interlayer collapse process on site and provide guidance and basis for the optimization design of the parameters of the cavity-dissolving engineering.

The technical scheme adopted by the invention for solving the technical problems is as follows: a method for judging interlayer collapse in the cavity-making period of a multi-interlayer salt cavern gas storage is characterized by comprising the following steps of:

s1) taking a single-well core for geological evaluation;

s2) carrying out geological horizon division on a salt layer and an interlayer in the target rock stratum according to the thickness value and lithology;

s3) the different layers are sequenced according to the depth, and the water soluble mineral ions SO of each layer are calculated₄ ^2-The total content;

s4) SO per horizon₄ ^2-Drawing a fluctuation change curve of the total content;

s5) based on cavity-dissolving back-halogenating Na₂SO₄The daily data of the concentration is used for drawing a time-varying curve;

s6) adding SO₄ ^2-Drawing a fluctuation curve and Na by total content₂SO₄And (5) judging the collapse condition of the interlayer by marking the concentration change curve correspondingly.

According to the technical scheme, the geological evaluation in the step S1) comprises the following contents: and analyzing lithology and carrying out a core water-soluble experiment to obtain the composition of rock components of each stratum of the target rock stratum and the composition data of the content of water-soluble mineral ions.

According to the technical scheme, the SO in the step S3)₄ ^2-The total content is calculated by water soluble mineral ions SO in each small layer in the layer₄ ^2-The contents are weighted and summed according to the thickness of the corresponding small layer.

According to the technical scheme, the abscissa of the fluctuation change curve in the step S4) is the horizon, and the ordinate is the corresponding SO₄ ^2-The total content is marked to obtain the fluctuation change rule of the total ion amount in different layersPeak point a₁...a_nValley point b₁...b_nN is the number of layers and the peak point is SO corresponding to the salt layer₄ ^2-Total content, valley point is SO corresponding to interlayer₄ ^2-And (4) the total content.

According to the technical scheme, the time-varying curve in the step S5) has the abscissa as time and the ordinate as cavity back-halogen Na₂SO₄The concentration is obtained, the time variation rule is obtained, and the peak point A is marked₁...A_nValley point B₁...B_n。

According to the above technical solution, step S6) includes the following contents: the peak point a₁...a_nAnd valley point b₁...b_nAre respectively reacted with A₁...A_nAnd B₁...B_nCorresponding mark, from a₁...a_nAnd b₁...b_nDetermining whether the corresponding horizon is a salt or an interlayer, from A₁...A_nAnd B₁...B_nAnd judging whether the corresponding interlayer collapses or not.

The invention has the beneficial effects that: compared with other on-site monitoring and indoor research and analysis methods, the method utilizes the on-site bittern-returning brine Na₂SO₄The concentration change can reflect the solution and dripping process and the change characteristic of the underground interlayer more truly without being influenced by conditions such as underground temperature, pressure and the like, static data such as geological lithology, rock chemical analysis, rock stratum component ion analysis and the like and brine ion dynamic data returned by the cavity dissolving engineering are combined, and the correlation of the two data and curve characteristic reaction of similar change are utilized, so that the integrated visual discrimination of the geological engineering is realized, the complicated mechanism and numerical simulation calculation analysis are avoided, the method can be applied to the discrimination of the interlayer collapse of the salt cavern gas storage well in the cavity construction period on site, and has the characteristics of rapidness, effectiveness, strong practicability and no operation cost.

Drawings

FIG. 1 is a SO according to an embodiment of the present invention₄ ^2-The total content change is plotted against different formations.

FIG. 2 is a graph illustrating the discrimination curves of one embodiment of the present invention.

FIG. 3 is a schematic diagram of a single well cavern of a multi-interbedded gas reservoir according to an embodiment of the invention.

Detailed Description

For a better understanding of the present invention, reference is made to the following description taken in conjunction with the accompanying drawings and examples.

The invention relates to a method for judging interlayer collapse based on geological rock stratum characteristics, rock stratum water-soluble substance ion content and field bittern-returning brine concentration change, which comprises the following steps:

(1) and (3) taking the single-well rock core for geological evaluation, analyzing lithology and carrying out a rock core water-soluble experiment to obtain the data of rock component composition and water-soluble mineral ion content composition of each stratum of the target rock stratum.

(2) And carrying out geological horizon division on salt layers and interlayers in the target rock stratum according to the thickness value and lithology (see figure 3).

(3) Calculating water soluble mineral ions SO of each layer according to the depth sequence of different layers₄ ^2-The total content is calculated by water soluble mineral ions SO in each small layer in the layer₄ ^2-The contents are weighted and summed according to the thickness of the corresponding small layer.

(4) According to SO₄ ^2-And (4) drawing a curve by the total content, wherein the horizontal coordinate is the horizon, and the vertical coordinate is the total ion amount, so as to obtain the fluctuation change rule of the total ion amount in different horizons. Marking the peak a₁、a₂、a₃...a_nValley point b₁、b₂、b₃...b_nThe peak point and the valley point are SO corresponding to different salt layers and interlayers₄ ^2-And (4) the total content.

(5) By reference to the lumen for returning brine Na₂SO₄Concentration day data is plotted, the abscissa is time, and the ordinate is cavern bittern-returning Na₂SO₄And (4) obtaining the time-varying rule of the concentration. Marking the Peak Point A₁、A₂、A₃...A_nValley point B₁、B₂、B₃...B_n。

(6) Applying the curve of the step (5) and converting the peak point a of the curve of the step (4)₁、a₂、a₃...a_nValley point b₁、b₂、b₃...b_nCorresponding to the mark A₁、A₂、A₃...A_n，B₁、B₂、B₃...B_n. From a to a₁、a₂、a₃...a_n，b₁、b₂、b₃...b_nAnd judging the corresponding salt layer or interlayer. From A₁、A₂、A₃...A_n，B₁、B₂、B₃...B_nAnd judging whether different interlayers collapse or not.

FIG. 1 shows SO in different salt layers and interlayers of a well rock layer₄ ^2-Total content change curve.

Fig. 2 is a discrimination graph. B can be determined according to the curve₁The collapse of interlayer No. 1 is over, A₂-B₂Is the whole process of the collapse of No. 2 interlayer, A₂The collapse of the interlayer No. 2 is started, the collapse conditions of other interlayers can be judged by analogy, and the collapse time of each interlayer can be judged according to a curve.