CN113266420B - Method for monitoring stability of cavity of salt cavern gas storage - Google Patents
Method for monitoring stability of cavity of salt cavern gas storage Download PDFInfo
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- CN113266420B CN113266420B CN202110479556.3A CN202110479556A CN113266420B CN 113266420 B CN113266420 B CN 113266420B CN 202110479556 A CN202110479556 A CN 202110479556A CN 113266420 B CN113266420 B CN 113266420B
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- 150000003839 salts Chemical class 0.000 title claims abstract description 195
- 238000012544 monitoring process Methods 0.000 title claims abstract description 138
- 238000000034 method Methods 0.000 title claims abstract description 58
- 230000002159 abnormal effect Effects 0.000 claims abstract description 92
- 238000004519 manufacturing process Methods 0.000 claims abstract description 82
- 230000005856 abnormality Effects 0.000 claims abstract description 15
- 238000011156 evaluation Methods 0.000 claims abstract description 15
- 239000007789 gas Substances 0.000 claims description 97
- 238000002347 injection Methods 0.000 claims description 73
- 239000007924 injection Substances 0.000 claims description 73
- 238000004062 sedimentation Methods 0.000 claims description 24
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 18
- 239000000700 radioactive tracer Substances 0.000 claims description 14
- 230000001687 destabilization Effects 0.000 claims description 10
- 239000003345 natural gas Substances 0.000 claims description 9
- 238000012797 qualification Methods 0.000 claims description 6
- 238000012360 testing method Methods 0.000 claims description 6
- 230000008859 change Effects 0.000 claims description 5
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 3
- 230000006835 compression Effects 0.000 claims description 3
- 238000007906 compression Methods 0.000 claims description 3
- 238000010276 construction Methods 0.000 claims description 3
- 238000003795 desorption Methods 0.000 claims description 3
- 230000005686 electrostatic field Effects 0.000 claims description 3
- 230000002045 lasting effect Effects 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 3
- 230000008439 repair process Effects 0.000 claims description 3
- 239000011435 rock Substances 0.000 claims description 3
- 238000004088 simulation Methods 0.000 claims description 3
- 239000011780 sodium chloride Substances 0.000 claims description 3
- 238000005516 engineering process Methods 0.000 description 7
- 238000007789 sealing Methods 0.000 description 3
- 238000004817 gas chromatography Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000009412 basement excavation Methods 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000011232 storage material Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
- E21F17/18—Special adaptations of signalling or alarm devices
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
- E21B49/08—Obtaining fluid samples or testing fluids, in boreholes or wells
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
- E21F17/16—Modification of mine passages or chambers for storage purposes, especially for liquids or gases
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
Abstract
The invention discloses a method for monitoring the stability of a salt cavern gas storage cavity, which comprises the following steps: step one, acquiring relevant parameters of a salt cavern gas storage and judging whether abnormality exists in a storage area, wherein the method comprises the following steps: 1) monitoring whether single well production dynamics are abnormal, 2) monitoring whether salt cavern cavity tightness is abnormal, 3) monitoring whether salt cavern cavity stability is abnormal, and 4) monitoring whether ground subsidence is abnormal; step two, according to the abnormal data in the monitoring process of the step one, the conditions of salt cavity creep, settlement, caving, collapse, leakage and the like which cause the instability of the salt cavity are specifically confirmed and processed: the method realizes the overall evaluation of the salt cavern gas storage stability monitoring system, defines various monitoring means, effectively monitors the creep, settlement, ledge, collapse, leakage and other conditions of the salt cavern, ensures the timely occurrence of problems, and ensures the safe use of the salt cavern and the operation safety of the staff in the storage area.
Description
Technical Field
The invention relates to the technical field of salt cavern gas storage, in particular to a method for monitoring the stability of a cavity of a salt cavern gas storage.
Background
Salt cavern gas storage is an artificial gas reservoir formed by re-injecting high-pressure natural gas into underground dissolved salt. Under the condition of frequent alternating stress of multi-period injection and production, the salt cavern is influenced by various factors such as complexity of underground geological structures, easy flowability of natural gas, sealing damage of cement rings, failure of injection and production pipe columns, high temperature, high pressure, high flow rate and the like, and accidents such as gas leakage, shaft damage and the like are easy to occur, so that a great safety risk exists in operation of the gas storage.
At present, four states of salt cavern destabilization are aimed at: creep, settlement, caving collapse and leakage, along with the use of the monitoring technology in the domestic salt cavern gas storage for more than ten years, the existing monitoring means can form a set of monitoring system which is suitable for field application and is effective. The single well operation parameters, ground subsidence and pressure measuring cavity have accumulated monitoring experience and data for more than ten years, and successful application of microseism monitoring indicates that new technology can gradually replace old technology so as to more perfect a monitoring system. In the early stage, the technologies of oil-gas exploration, cavity stopping and pressure stabilizing and the like are considered for the monitoring technology, but the technologies are replaced by the excessive investment in the monitoring period, wherein the implementation of the oil-gas exploration technology needs to carry out excavation operation around a wellhead, and belongs to high-risk operation in the injection and production period; and the cavity-stopping pressure-stabilizing monitoring needs to re-inject halogen into the produced injection well for exhausting, so that the monitoring cost is high.
Based on the above problems, a corresponding monitoring method is provided for the instability of the salt cavern cavity so as to ensure the long-term stable operation of the salt cavern gas storage cavity.
Disclosure of Invention
The invention aims to provide a method for monitoring the stability of a salt cavern gas storage cavity, which can effectively monitor the instability condition of the salt cavern cavity of the salt cavern gas storage.
For this purpose, the technical scheme of the invention is as follows:
a method for monitoring the stability of a cavity of a salt cavern gas storage comprises the following steps:
step one, acquiring relevant parameters of a salt cavern gas storage and judging whether abnormality exists in a storage area, wherein the method comprises the following steps: 1) monitoring whether single well production dynamics are abnormal, 2) monitoring whether salt cavern cavity tightness is abnormal, 3) monitoring whether salt cavern cavity stability is abnormal, and 4) monitoring whether ground subsidence is abnormal; the monitoring of whether the salt cavern cavity tightness is abnormal or not is realized through monitoring the pressure state of a monitoring well, the tracer and microseism; monitoring whether the stability of the salt caverns is abnormal or not is realized by five stability evaluation indexes, namely tensile stress, plastic area evaluation, linear expansion coefficient, creep rate and volume shrinkage rate, of the salt caverns;
step two, confirming the specific condition of causing instability of salt cavern cavities according to the data abnormality in the monitoring process of the step one, wherein the specific steps are as follows:
1) When the production dynamic state of a certain salt cavity in the first step is abnormal, the method comprises the following steps:
(1) the microseism monitoring result of the latest time is called, and whether two destabilization conditions of ledge or collapse exist in the salt cavern cavity at present is judged by combining production dynamic abnormal data; or alternatively, the first and second heat exchangers may be,
(2) the method comprises the steps of calling a salt cavity stability monitoring result in the latest time, and judging whether two destabilization conditions of ledge or collapse exist in the salt cavity at present by combining production dynamic abnormal data;
2) When the tracer in the second step monitors that a certain salt cavity is likely to have leakage, then:
(1) the recent production dynamic abnormal data of the salt cavern cavity is called, and whether leakage exists in the salt cavern cavity at present is further judged; and/or the number of the groups of groups,
(2) the microseism monitoring result in the latest time and the monitoring result corresponding to the pressure state of the monitoring well are called, and whether leakage exists in the salt cavern cavity or not is further judged;
3) When the stability of a certain salt cavity in the first step is abnormal, the method comprises the following steps:
(1) judging whether two destabilization conditions of creep or sedimentation exist in the salt cavern currently according to the abnormal data; and, a step of, in the first embodiment,
(2) the salt cavern stability monitoring result in the latest time is called, and whether two instability conditions of creep or settlement exist in the salt cavern currently is judged by combining the salt cavern stability abnormal data;
in the cases 1) to 3) of the above step two,
if the salt cavern cavity does not currently have four instability conditions of creep, settlement, lasting and collapse, the current monitoring data and the historical monitoring data are called to establish a simulation model, and whether the salt cavern cavity has possibility of impending instability conditions of corresponding types is pre-judged; if the possibility of instability is about to occur, adjusting working parameters of the salt cavern cavity, including upper limit pressure of the cavity, lower limit pressure of the cavity, gas injection production rate and gas production rate;
if the salt cavern cavity does currently have four instability conditions of creep, settlement, caving and collapse, adjusting working parameters of the salt cavern cavity, including upper limit pressure of the cavity, lower limit pressure of the cavity, gas injection and production rate and gas production rate;
if the salt cavern cavity has the leakage condition currently, well repair or well abandonment is selected according to the leakage condition.
Further, in the first step, the method for monitoring whether the single well production dynamics have abnormality comprises the following steps: the method comprises the steps of collecting wellhead pressure, bottom hole temperature and wellhead flow of an injection well in real time, collecting wellhead pressure and bottom hole temperature of a monitoring well in real time, and judging as follows:
1) During the gas injection period of the injection well, if the pressure and the temperature of the salt cavern cavity are gradually increased and the gas storage amount of the salt cavern cavity is gradually increased, judging that the production state of the injection well is normal; otherwise, judging the production state of the injection well as abnormal;
2) During the gas production period of the injection and production well, if the pressure of the salt cavern cavity is gradually reduced, the temperature is gradually reduced, and the gas storage quantity of the salt cavern cavity is gradually reduced, the production state of the injection and production well is judged to be normal; otherwise, judging the production state of the injection well as abnormal;
3) In the well stopping period after gas injection, if the salt cavern cavity pressure gradually drops to the balance point, the temperature gradually recovers to the stratum temperature, and the salt cavern cavity gas storage amount is unchanged, judging that the production state of the injection well is normal; otherwise, judging the production state of the injection well as abnormal;
4) In the well stopping period of the injection and production well after gas production, if the salt cavern cavity pressure gradually rises to the balance point, the temperature gradually recovers to the stratum temperature, and the salt cavern cavity inventory gas quantity is unchanged, judging that the production state of the injection and production well is normal; otherwise, judging the production state of the injection well as abnormal;
5) The monitoring well is in any state, and if the wellhead pressure value and the bottom hole temperature value are basically maintained in the unchanged state, the monitoring well state is judged to be normal; otherwise, the monitoring well state is judged to be abnormal;
6) Using the gas state equation:calculating the cavity pressure as P i Corresponding stock natural gas quantity DeltaV Library And compares it with DeltaV 'calculated using wellhead flow data of the injection well' Library Comparing the values of DeltaV Library And DeltaV' Library If the error rate does not exceed the qualified threshold, judging that the state of the injection well is normal; otherwise, judging the production state of the injection well as abnormal; wherein V is c Is the volume of the cavity, T c For the cavity temperature, T 0 Is the gas temperature under the standard condition; p (P) 0 Z is the gas pressure under standard conditions i Is the natural gas compression factor in state i;
in any of the above cases 1) to 6), if any of the cases is judged to be abnormal, there is an abnormality in the production dynamics of the salt cavern.
Further, the tracer monitoring is at least once a year, and the microseismic monitoring is at least once a year.
Further, in the first step, the method for monitoring whether the salt cavity sealing performance is abnormal comprises the following steps:
monitoring the pressure state of a well: collecting wellhead pressure and shaft annular pressure of a monitoring well in real time; if the wellhead pressure value and the shaft annulus pressure value are basically maintained in the unchanged state, the monitoring well state is judged to be normal; otherwise, the monitoring well state is judged to be abnormal;
tracer monitoring: the method comprises the steps of simultaneously injecting trace gas into a salt cavern cavity in the gas injection process of an injection well at regular intervals, and collecting multi-point air samples in a full reservoir area by adopting an atmosphere sampler after 1 month; then separating a plurality of air samples by using a gas chromatography Fourier transform electrostatic field orbit trap mass spectrometer, a multi-atmosphere thermal desorption furnace and an ultra-high resolution mass spectrometerAnalyzing to obtain the concentration of the trace gas in each air sample, and determining the salt cavity position where the trace gas is likely to leak by reversely tracking the air sample for detecting the trace gas; wherein, the injection amount of the tracer gas in each salt cavern is as follows: at every 25×10 4 m 3 5m of saline hole cavity injection 3 Is a trace gas of (2);
microseism monitoring: and (3) regularly carrying out microseism monitoring on the reservoir area, and analyzing whether the underground fault is activated or whether the salt cavern cavity is collapsed or not by collecting underground sound data.
Further, in the first step, the method for monitoring whether the stability of the salt cavern is abnormal is as follows: the cavity morphology and the volume of each salt cavity are measured by adopting a sonar logging method with pressure at regular intervals, and the following judgment is carried out:
1) When the current cavity shape of the salt cavity is compared with the cavity shape measured last time, judging that the cavity shape of the salt cavity is abnormal when the local structure is absent or arched in the current cavity shape;
2) When the current inner cavity volume of the salt cavity is compared with the inner cavity volume measured before, the annual average change rate of the current inner cavity volume is more than or equal to 1%, judging that the inner cavity volume of the salt cavity is abnormal;
3) Substituting data obtained by monitoring the corresponding under-pressure sonar of each salt cavity, stratum parameters of a reservoir area, rock mechanical test parameters, ground stress test data, construction operation history data, mechanical parameter checking data, salt cavity geometric parameters and salt cavity operation parameters into abaqus and/or Flac3D software to obtain five stability evaluation index results of tensile stress, plastic area evaluation, linear expansion coefficient, creep rate and volume shrinkage rate; comparing the obtained result with a set qualification threshold, and judging the stability of the salt cavity as abnormal if any stability evaluation index result is not within the qualification threshold;
in any of the above cases 1) to 3), if any of the cases is judged to be abnormal, the stability of the salt cavity is abnormal.
Further, monitoring salt cavity stability is monitored at least once every three years.
Further, in the first step, the method for monitoring whether the ground subsidence is abnormal comprises the following steps: the ground subsidence condition of the reservoir area is monitored by a leveling method or a synthetic aperture radar method at regular intervals to obtain the ground subsidence quantity of the reservoir area in the current year, wherein the ground subsidence quantity comprises the subsidence quantity in the vertical direction and the subsidence quantity in the horizontal direction, the ground subsidence total quantity from the initial time of measurement to the current year comprises the ground vertical subsidence total quantity and the ground horizontal subsidence total quantity, and the annual ground average subsidence rate comprises the annual ground vertical average subsidence rate and the annual ground horizontal average subsidence rate, and the following judgment is carried out:
1) If the total vertical ground sedimentation is more than or equal to 250mm or the total horizontal ground sedimentation is more than or equal to 150mm, judging that the ground sedimentation is abnormal;
2) If the annual ground average sedimentation rate in the reservoir occurs three years in succession: the annual ground horizontal average sedimentation rate is more than or equal to 15 mm/year or the annual ground vertical average sedimentation rate is more than or equal to 20 mm/year, and judging that the ground sedimentation is abnormal;
in the above cases 1) and 2), if any one of the cases is judged to be abnormal, there is an abnormality in the ground subsidence.
Further, ground subsidence monitoring is performed at least once a year.
Compared with the prior art, the method for monitoring the stability of the salt cavern gas storage cavity realizes the overall evaluation of a salt cavern gas storage stability monitoring system, defines various monitoring means required to be implemented in the salt cavern stability monitoring process, indicates the composition of the comprehensive method, effectively monitors the conditions of creep, settlement, ledge, collapse, leakage and the like of the salt cavern, ensures the timely occurrence of problems, and ensures the safe use of the salt cavern and the operation safety of the staff in a storage area.
Drawings
FIG. 1 is a flow chart of a method of salt cavern gas storage cavity stability monitoring of the present invention.
Detailed Description
The invention will now be further described with reference to the accompanying drawings and specific examples, which are in no way limiting.
Specifically, in this embodiment, the salt cavern reservoir area is provided with a plurality of single-well single-cavity salt caverns, and the specific storage materials are energy gases such as natural gas, hydrogen and the like; each salt cavern cavity is provided with only one channel communicated with the ground, and the channel is a vertical well or a directional well; the effective volume of each salt cavity is about 5-100 square, the diameter of the cavity is 60-80 m, the distance between the top of the cavity and the salt top is 25-35 m, and the distance between the top of the cavity and the production sleeve shoes is 10-15 m.
As shown in fig. 1, the method for monitoring the stability of the cavity of the salt cavern gas storage comprises the following specific monitoring methods:
step one, acquiring relevant parameters of a salt cavern gas storage and a storage area where the salt cavern gas storage is positioned, and judging whether abnormality exists;
1. single well production dynamic monitoring:
the method comprises the steps of collecting wellhead pressure, bottom hole temperature and wellhead flow of an injection well in real time, collecting wellhead pressure and bottom hole temperature of a monitoring well in real time, and judging as follows:
1) During the gas injection period of the injection well, if the pressure and the temperature of the salt cavern cavity are gradually increased and the gas storage amount of the salt cavern cavity is gradually increased, judging that the production state of the injection well is normal; otherwise, judging the production state of the injection well as abnormal;
2) During the gas production period of the injection and production well, if the pressure of the salt cavern cavity is gradually reduced, the temperature is gradually reduced, and the gas storage quantity of the salt cavern cavity is gradually reduced, the production state of the injection and production well is judged to be normal; otherwise, judging the production state of the injection well as abnormal;
3) In the well stopping period after gas injection, if the salt cavern cavity pressure gradually drops to the balance point, the temperature gradually recovers to the stratum temperature, and the salt cavern cavity gas storage amount is unchanged, judging that the production state of the injection well is normal; otherwise, judging the production state of the injection well as abnormal;
4) In the well stopping period of the injection and production well after gas production, if the salt cavern cavity pressure gradually rises to the balance point, the temperature gradually recovers to the stratum temperature, and the salt cavern cavity inventory gas quantity is unchanged, judging that the production state of the injection and production well is normal; otherwise, judging the production state of the injection well as abnormal;
5) The monitoring well is in any state, and if the wellhead pressure value and the bottom hole temperature value are kept in a basically unchanged state (if the set change rate is always kept within 0.5 percent), the monitoring well state is judged to be normal; otherwise, the monitoring well state is judged to be abnormal;
6) Using the gas state equation:calculating the cavity pressure as P i Corresponding stock natural gas quantity DeltaV Library And compares it with DeltaV 'calculated using wellhead flow data of the injection well' Library Comparing the values of DeltaV Library And DeltaV' Library If the error rate between the two is not beyond the qualified threshold (if the qualified threshold is set to +/-1%), the state of the injection well is judged to be normal; otherwise, judging the production state of the injection well as abnormal; wherein V is c Is the volume of the cavity, T c For the cavity temperature, T 0 Is the gas temperature under the standard condition; p (P) 0 Z is the gas pressure under standard conditions i Is the natural gas compression factor in state i;
in any of the above cases 1) to 6), if any of the cases is judged to be abnormal, there is an abnormality in the production dynamics of the salt cavern.
2. Salt cavern sealing performance monitoring:
2-1, monitoring the pressure state of the monitoring well:
collecting wellhead pressure and shaft annular pressure of a monitoring well in real time; if the wellhead pressure value and the well bore annulus pressure value are kept in a basically unchanged state (if the set change rate is always kept within 0.5 percent), the monitoring well state is judged to be normal; otherwise, the monitoring well state is judged to be abnormal.
2-2, tracer monitoring:
the tracer gas (SF 6) is injected into the salt cavern cavity at the same time in the gas injection process of the injection well at regular intervals (such as once a year), and after 1 month, an atmosphere sampler is adopted to collect multi-point air samples in the whole reservoir area; then separating and analyzing a plurality of air samples by utilizing a gas chromatography Fourier transform electrostatic field orbit trap mass spectrometer, a multi-atmosphere thermal desorption furnace and an ultra-high resolution mass spectrometer to obtain the concentration of trace gas (SF 6) in each air sample, and reversely detecting the air sample showing the trace gasTracking, and determining salt cavern positions where trace gas leakage is likely to exist; wherein, the injection amount of the tracer gas in each salt cavern is as follows: at every 25×10 4 m 3 5m of saline hole cavity injection 3 Is used for the trace gas of the (a).
2-3, microseism monitoring:
microseismic monitoring is performed on the reservoir area periodically (e.g., once a year), and by collecting downhole acoustic data, it is analyzed whether downhole faults are activated or whether salt caverns collapse.
3. Salt cavern stability monitoring:
the cavity morphology and volume of each salt cavity are measured by adopting a sonar logging method with pressure at regular intervals (every 3 years), and the following judgment is carried out:
1) When the current cavity shape of the salt cavity is compared with the cavity shape measured last time, judging that the cavity shape of the salt cavity is abnormal when the local structure is absent or arched in the current cavity shape;
2) When the current inner cavity volume of the salt cavity is compared with the inner cavity volume measured before, the annual average change rate of the current inner cavity volume is more than or equal to 1%, judging that the inner cavity volume of the salt cavity is abnormal;
3) Substituting data obtained by monitoring the corresponding under-pressure sonar of each salt cavity, stratum parameters of a reservoir area, rock mechanical test parameters, ground stress test data, construction operation history data, mechanical parameter checking data, salt cavity geometric parameters and salt cavity operation parameters into abaqus and/or Flac3D software to obtain five stability evaluation index results of tensile stress, plastic area evaluation, linear expansion coefficient, creep rate and volume shrinkage rate; comparing the obtained result with a set qualification threshold, and judging the stability of the salt cavity as abnormal if any stability evaluation index result is not within the qualification threshold;
in any of the above cases 1) to 3), if any of the cases is judged to be abnormal, the stability of the salt cavity is abnormal.
4. Ground subsidence monitoring:
the ground subsidence condition of the reservoir area is monitored by adopting a leveling method or a synthetic aperture radar method every year to obtain the ground subsidence quantity (including the subsidence quantity in the vertical direction, namely the subsidence quantity in the vertical direction and the subsidence quantity in the horizontal direction, namely the horizontal subsidence quantity) of the reservoir area in the current year, the total ground subsidence quantity (including the total ground vertical subsidence quantity and the total ground horizontal subsidence quantity) from the initial measurement time to the current year, and the annual ground average subsidence rate (including the annual ground vertical average subsidence rate and the annual ground horizontal average subsidence rate), and the following judgment is carried out:
1) If the total vertical ground sedimentation is more than or equal to 250mm or the total horizontal ground sedimentation is more than or equal to 150mm, judging that the ground sedimentation is abnormal;
2) If the annual ground average sedimentation rate in the reservoir occurs three years in succession: the annual ground horizontal average sedimentation rate is more than or equal to 15 mm/year or the annual ground vertical average sedimentation rate is more than or equal to 20 mm/year, and judging that the ground sedimentation is abnormal;
in the above cases 1) and 2), when any one of the cases is judged to be abnormal, there is an abnormality in the ground subsidence;
step two, confirming the specific condition of causing instability of salt cavern cavities according to the data abnormality in the monitoring process of the step one:
1) When the production dynamic state of a certain salt cavity in the first step is abnormal, the method comprises the following steps:
(1) the microseism monitoring result of the latest time is called, and whether two destabilization conditions of ledge or collapse exist in the salt cavern cavity at present is judged by combining production dynamic abnormal data; or alternatively, the first and second heat exchangers may be,
(2) the method comprises the steps of calling a salt cavity stability monitoring result in the latest time, and judging whether two destabilization conditions of ledge or collapse exist in the salt cavity at present by combining production dynamic abnormal data; 2) When the tracer in the second step monitors that a certain salt cavity is likely to have leakage, then:
(1) the recent production dynamic abnormal data of the salt cavern cavity is called, and whether leakage exists in the salt cavern cavity at present is further judged; and/or the number of the groups of groups,
(2) the microseism monitoring result in the latest time and the monitoring result corresponding to the pressure state of the monitoring well are called, and whether leakage exists in the salt cavern cavity or not is further judged;
3) When the stability of a certain salt cavity in the third step is abnormal, the following steps are:
(1) judging whether two destabilization conditions of creep or sedimentation exist in the salt cavern currently according to the abnormal data; and, a step of, in the first embodiment,
(2) the salt cavern stability monitoring result in the latest time is called, and whether two instability conditions of creep or settlement exist in the salt cavern currently is judged by combining the salt cavern stability abnormal data;
in the cases 1) to 3) of the above step two,
if the salt cavern cavity does not currently have four instability conditions of creep, settlement, lasting and collapse, the current monitoring data and the historical monitoring data are called to establish a simulation model, and whether the salt cavern cavity has possibility of impending instability conditions of corresponding types is pre-judged; if the possibility of instability is about to occur, adjusting working parameters of the salt cavern cavity, including upper limit pressure of the cavity, lower limit pressure of the cavity, gas injection production rate and gas production rate;
if the salt cavern cavity does currently have four instability conditions of creep, settlement, caving and collapse, adjusting working parameters of the salt cavern cavity, including upper limit pressure of the cavity, lower limit pressure of the cavity, gas injection and production rate and gas production rate;
if the salt cavern cavity has the leakage condition currently, well repair or well abandonment is selected according to the leakage condition.
The foregoing description is only for the convenience of those skilled in the art to understand the technical solution of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. The method for monitoring the stability of the cavity of the salt cavern gas storage is characterized by comprising the following steps:
step one, acquiring relevant parameters of a salt cavern gas storage and judging whether abnormality exists in a storage area, wherein the method comprises the following steps: 1) monitoring whether single well production dynamics are abnormal, 2) monitoring whether salt cavern cavity tightness is abnormal, 3) monitoring whether salt cavern cavity stability is abnormal, and 4) monitoring whether ground subsidence is abnormal; the monitoring of whether the salt cavern cavity tightness is abnormal or not is realized through monitoring the pressure state of a monitoring well, the tracer and microseism; monitoring whether the stability of the salt caverns is abnormal or not is realized by five stability evaluation indexes, namely tensile stress, plastic area evaluation, linear expansion coefficient, creep rate and volume shrinkage rate, of the salt caverns;
step two, confirming the specific condition of causing instability of salt cavern cavities according to the data abnormality in the monitoring process of the step one, wherein the specific steps are as follows:
1) When the production dynamic state of a certain salt cavity in the first step is abnormal, the method comprises the following steps:
(1) the microseism monitoring result of the latest time is called, and whether two destabilization conditions of ledge or collapse exist in the salt cavern cavity at present is judged by combining production dynamic abnormal data; or alternatively, the first and second heat exchangers may be,
(2) the method comprises the steps of calling a salt cavity stability monitoring result in the latest time, and judging whether two destabilization conditions of ledge or collapse exist in the salt cavity at present by combining production dynamic abnormal data;
2) When the tracer detects that a salt cavity may have leakage in the first step, then:
(1) the recent production dynamic abnormal data of the salt cavern cavity is called, and whether leakage exists in the salt cavern cavity at present is further judged; and/or the number of the groups of groups,
(2) the microseism monitoring result in the latest time and the monitoring result corresponding to the pressure state of the monitoring well are called, and whether leakage exists in the salt cavern cavity or not is further judged;
3) When the stability of a certain salt cavity in the first step is abnormal, the method comprises the following steps:
(1) judging whether two destabilization conditions of creep or sedimentation exist in the salt cavern currently according to the abnormal data; and, a step of, in the first embodiment,
(2) the salt cavern stability monitoring result in the latest time is called, and whether two instability conditions of creep or settlement exist in the salt cavern currently is judged by combining the salt cavern stability abnormal data;
in the cases 1) to 3) of the above step two,
if the salt cavern cavity does not currently have four instability conditions of creep, settlement, lasting and collapse, the current monitoring data and the historical monitoring data are called to establish a simulation model, and whether the salt cavern cavity has possibility of impending instability conditions of corresponding types is pre-judged; if the possibility of instability is about to occur, adjusting working parameters of the salt cavern cavity, including upper limit pressure of the cavity, lower limit pressure of the cavity, gas injection production rate and gas production rate;
if the salt cavern cavity does currently have four instability conditions of creep, settlement, caving and collapse, adjusting working parameters of the salt cavern cavity, including upper limit pressure of the cavity, lower limit pressure of the cavity, gas injection and production rate and gas production rate;
if the salt cavern cavity has the leakage condition currently, well repair or well abandonment is selected according to the leakage condition.
2. The method for monitoring the stability of a salt cavern gas storage cavity according to claim 1, wherein in the step one, the method for monitoring whether the single well production dynamics have abnormality is as follows: the method comprises the steps of collecting wellhead pressure, bottom hole temperature and wellhead flow of an injection well in real time, collecting wellhead pressure and bottom hole temperature of a monitoring well in real time, and judging as follows:
1) During the gas injection period of the injection well, if the pressure and the temperature of the salt cavern cavity are gradually increased and the gas storage amount of the salt cavern cavity is gradually increased, judging that the production state of the injection well is normal; otherwise, judging the production state of the injection well as abnormal;
2) During the gas production period of the injection and production well, if the pressure of the salt cavern cavity is gradually reduced, the temperature is gradually reduced, and the gas storage quantity of the salt cavern cavity is gradually reduced, the production state of the injection and production well is judged to be normal; otherwise, judging the production state of the injection well as abnormal;
3) In the well stopping period after gas injection, if the salt cavern cavity pressure gradually drops to the balance point, the temperature gradually recovers to the stratum temperature, and the salt cavern cavity gas storage amount is unchanged, judging that the production state of the injection well is normal; otherwise, judging the production state of the injection well as abnormal;
4) In the well stopping period of the injection and production well after gas production, if the salt cavern cavity pressure gradually rises to the balance point, the temperature gradually recovers to the stratum temperature, and the salt cavern cavity inventory gas quantity is unchanged, judging that the production state of the injection and production well is normal; otherwise, judging the production state of the injection well as abnormal;
5) The monitoring well is in any state, and if the wellhead pressure value and the bottom hole temperature value are basically maintained in the unchanged state, the monitoring well state is judged to be normal; otherwise, the monitoring well state is judged to be abnormal;
6) Using the gas state equation:calculating the cavity pressure as P i Corresponding stock natural gas quantity DeltaV Library And compares it with DeltaV 'calculated using wellhead flow data of the injection well' Library Comparing the values of DeltaV Library And DeltaV' Library If the error rate does not exceed the qualified threshold, judging that the state of the injection well is normal; otherwise, judging the production state of the injection well as abnormal; wherein V is c Is the volume of the cavity, T c For the cavity temperature, T 0 Is the gas temperature under the standard condition; p (P) 0 Z is the gas pressure under standard conditions i Is the natural gas compression factor in state i;
in any of the above cases 1) to 6), if any of the cases is judged to be abnormal, there is an abnormality in the production dynamics of the salt cavern.
3. The method for monitoring the stability of a salt cavern gas storage cavity according to claim 1, wherein in the first step, the method for monitoring whether the salt cavern cavity tightness is abnormal is as follows:
monitoring the pressure state of a well: collecting wellhead pressure and shaft annular pressure of a monitoring well in real time; if the wellhead pressure value and the shaft annulus pressure value are basically maintained in the unchanged state, the monitoring well state is judged to be normal; otherwise, the monitoring well state is judged to be abnormal;
tracer monitoring: the method comprises the steps of simultaneously injecting trace gas into a salt cavern cavity in the gas injection process of an injection well at regular intervals, and collecting multi-point air samples in a full reservoir area by adopting an atmosphere sampler after 1 month; then utilizing gas chromatograph Fourier transform electrostatic field orbit trap mass spectrometer and multipleThe method comprises the steps of separating and analyzing a plurality of air samples by an atmosphere thermal desorption furnace and an ultra-high resolution mass spectrometer to obtain the concentration of trace gas in each air sample, and determining the salt cavity position where trace gas leakage possibly exists by carrying out reverse tracking on the air sample for detecting the trace gas; wherein, the injection amount of the tracer gas in each salt cavern is as follows: at every 25×10 4 m 3 5m of saline hole cavity injection 3 Is a trace gas of (2);
microseism monitoring: and (3) regularly carrying out microseism monitoring on the reservoir area, and analyzing whether the underground fault is activated or whether the salt cavern cavity is collapsed or not by collecting underground sound data.
4. A method of salt cavern gas storage cavity stability monitoring as claimed in claim 3 wherein tracer monitoring is at least once per year and microseismic monitoring is at least once per year.
5. The method for monitoring the stability of a salt cavern gas storage cavity according to claim 1, wherein in the first step, the method for monitoring whether the stability of the salt cavern cavity is abnormal is as follows: the cavity morphology and the volume of each salt cavity are measured by adopting a sonar logging method with pressure at regular intervals, and the following judgment is carried out:
1) When the current cavity shape of the salt cavity is compared with the cavity shape measured last time, judging that the cavity shape of the salt cavity is abnormal when the local structure is absent or arched in the current cavity shape;
2) When the current inner cavity volume of the salt cavity is compared with the inner cavity volume measured before, the annual average change rate of the current inner cavity volume is more than or equal to 1%, judging that the inner cavity volume of the salt cavity is abnormal;
3) Substituting data obtained by monitoring the corresponding under-pressure sonar of each salt cavity, stratum parameters of a reservoir area, rock mechanical test parameters, ground stress test data, construction operation history data, mechanical parameter checking data, salt cavity geometric parameters and salt cavity operation parameters into abaqus and/or Flac3D software to obtain five stability evaluation index results of tensile stress, plastic area evaluation, linear expansion coefficient, creep rate and volume shrinkage rate; comparing the obtained result with a set qualification threshold, and judging the stability of the salt cavity as abnormal if any stability evaluation index result is not within the qualification threshold;
in any of the above cases 1) to 3), if any of the cases is judged to be abnormal, the stability of the salt cavity is abnormal.
6. A method of salt cavern gas storage cavity stability monitoring as claimed in claim 5 wherein in step one salt cavern cavity stability monitoring is monitored at least once every three years.
7. The method for monitoring the stability of a salt cavern gas storage cavity according to claim 1, wherein in the first step, the method for monitoring whether the ground subsidence is abnormal is as follows: the ground subsidence condition of the reservoir area is monitored by a leveling method or a synthetic aperture radar method at regular intervals to obtain the ground subsidence quantity of the reservoir area in the current year, wherein the ground subsidence quantity comprises the subsidence quantity in the vertical direction and the subsidence quantity in the horizontal direction, the ground subsidence total quantity from the initial time of measurement to the current year comprises the ground vertical subsidence total quantity and the ground horizontal subsidence total quantity, and the annual ground average subsidence rate comprises the annual ground vertical average subsidence rate and the annual ground horizontal average subsidence rate, and the following judgment is carried out:
1) If the total vertical ground sedimentation is more than or equal to 250mm or the total horizontal ground sedimentation is more than or equal to 150mm, judging that the ground sedimentation is abnormal;
2) If the annual ground average sedimentation rate in the reservoir occurs three years in succession: the annual ground horizontal average sedimentation rate is more than or equal to 15 mm/year or the annual ground vertical average sedimentation rate is more than or equal to 20 mm/year, and judging that the ground sedimentation is abnormal;
in the above cases 1) and 2), if any one of the cases is judged to be abnormal, there is an abnormality in the ground subsidence.
8. A method of salt cavern gas storage cavity stability monitoring as claimed in claim 7 wherein in step one, ground subsidence is monitored at least once per year.
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