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CN-120706046-B - Method for predicting cold and hot cycle damage of granular rock

CN120706046BCN 120706046 BCN120706046 BCN 120706046BCN-120706046-B

Abstract

The invention relates to the technical field of cold and hot circulation damage treatment, in particular to a granular rock cold and hot circulation damage prediction method, which comprises the steps of establishing a numerical model based on grains by using discrete element software, setting initial temperature and confining pressure of a rock sample, constructing heating, balancing and cooling experimental processes, setting different preset temperature values, heating and cooling step sizes, obtaining elastic modulus damage and crack quantity development, calculating thermal damage by using the elastic modulus damage and the crack quantity development, obtaining the relation between thermal strain of different confining pressure rock volumes and rock heating-cooling damage, and constructing damage prediction models of different confining pressure rocks under cold and hot circulation conditions. According to the invention, a thermal damage and volumetric thermal strain model which takes heating and cooling into consideration is constructed aiming at the problem of rock damage caused by rock heating expansion and cooling shrinkage, and the model has strong universality.

Inventors

  • ZHANG SHIFENG
  • XU YUQING
  • CUI XINYING
  • ZHUANG YAN
  • Xing Qinze

Assignees

  • 常州大学

Dates

Publication Date
20260505
Application Date
20250604

Claims (7)

  1. 1. The method for predicting the cold and hot cycle damage of the granular rock is characterized by comprising the following steps of: firstly, collecting quartz content of a rock core, and establishing a numerical model based on particles by using discrete meta-software; setting initial temperature and confining pressure of the rock sample, and constructing heating, balancing and cooling experimental processes; Thirdly, calculating thermal damage by utilizing elastic modulus damage and crack quantity development to obtain the relation between thermal strain of different confining pressure rock volumes and rock heating-cooling damage, and constructing damage prediction models of different confining pressure rocks under the condition of cold-hot circulation; calculating thermal damage using elastic modulus damage and crack count development includes: Calculating the thermal damage of the rock through elastic modulus reduction after circulation; Solving the temperature rise damage and the temperature reduction damage of each cycle reversely; the formula of the temperature rise damage is as follows: D H =1-(1-D T1 )(1-D T3 ); (2) Wherein D T1 is the ratio of the number of broken microelements after the 1 st cycle temperature rise to the total number of the microelements before the rock damage, and D T3 is the ratio of the number of broken microelements after the 2 nd cycle temperature rise to the total number of the microelements before the rock damage; The formula of cooling damage is as follows: D C =1-(1-D T2 )(1-D T4 ); (3) wherein D T2 is the ratio of the number of broken microelements after the 1 st cycle cooling to the total number of the microelements before the rock breaking, and D T4 is the ratio of the number of broken microelements after the 2 nd cycle cooling to the total number of the microelements before the rock breaking.
  2. 2. The method for predicting cyclic damage to crystalline rock Dan Lengre as recited in claim 1, wherein the second step specifically comprises: And (3) when the first circulation of the first preset temperature is carried out, firstly carrying out 1 ℃ per 100 steps from the initial temperature, keeping the temperature circulation for 5000 steps after the temperature is raised to the first preset temperature value, and then carrying out 1 ℃ per 100 steps to reduce the temperature and stopping after returning to the initial temperature.
  3. 3. The method for predicting cyclic damage to crystalline rock Dan Lengre as recited in claim 1, wherein the damage prediction model is formulated as: (4) Wherein, the Is the damage of rock caused by the influence of temperature transformation; Is the volumetric thermal strain, K, m is the weibull distribution scale parameter and the shape parameter respectively.
  4. 4. The method for predicting cyclic damage to crystalline rock Dan Lengre as claimed in claim 2, wherein the initial temperature is 25 ℃, and the confining pressure is 0, 15, 45, 120MPa.
  5. 5. The method of claim 2, wherein the predetermined temperature values include 150 °, 300 °, 600 °.
  6. 6. A system for predicting cold and hot cyclic damage to a granular rock, comprising a memory for storing instructions executable by a processor, and a processor for executing the instructions to implement the cyclic damage predicting method for a granular rock Dan Lengre as set forth in any one of claims 1-5.
  7. 7. A computer readable medium storing computer program code, characterized in that the computer program code, when executed by a processor, implements the cyclic damage prediction method of grain-like rock Dan Lengre as defined in any one of claims 1-5.

Description

Method for predicting cold and hot cycle damage of granular rock Technical Field The invention relates to the technical field of cold and hot cycle damage treatment, in particular to a method for predicting cold and hot cycle damage of granular rock. Background The dry hot rock energy source is spotlighted as a brand-new renewable energy source, and has great potential, but the development and utilization of the dry hot rock energy source still face a series of challenges; In the dry hot rock drilling process, the damage state of stratum rock is analyzed in time, and the mechanical property has profound influence on the exploitation efficiency and safety of the dry hot rock. The publication number is CN117473716A, the rock thermal damage prediction method based on PFC value research of different compositions adopts the relation between thermal damage and volumetric thermal strain, but the model has no theoretical support and has poor model compatibility. Disclosure of Invention Aiming at the defects of the existing method, the invention builds a thermal damage and volumetric thermal strain model which gives consideration to heating and cooling aiming at the problem of rock damage caused by rock heating expansion and cooling contraction, has strong universality, predicts the damage state and mechanical property of stratum rock at a certain depth in the drilling process of an oil-gas field, and provides guarantee for exploitation of the oil-gas field. The technical scheme adopted by the invention is that the method for predicting the cold and hot cycle damage of the granular rock comprises the following steps: firstly, collecting quartz content of a rock core, and establishing a numerical model based on particles by using discrete meta-software; setting initial temperature and confining pressure of the rock sample, and constructing heating, balancing and cooling experimental processes; as a preferred embodiment of the present invention, the second step specifically includes: And (3) when the first circulation of the first preset temperature is carried out, firstly carrying out 1 ℃ per 100 steps from the initial temperature, keeping the temperature circulation for 5000 steps after the temperature is raised to the first preset temperature value, and then carrying out 1 ℃ per 100 steps to reduce the temperature and stopping after returning to the initial temperature. As a preferred embodiment of the invention, the initial temperature is 25 ℃, and the confining pressure is 0, 15, 45 and 120MPa. As a preferred embodiment of the present invention, the preset temperature value includes 150 °, 300 °, 600 °. Thirdly, calculating thermal damage by utilizing elastic modulus damage and crack quantity development to obtain the relation between thermal strain of different confining pressure rock volumes and rock heating-cooling damage, and constructing damage prediction models of different confining pressure rocks under the condition of cold-hot circulation; as a preferred embodiment of the present invention, calculating thermal damage using elastic modulus damage and crack number development comprises: Calculating the thermal damage of the rock through elastic modulus reduction after circulation; and solving the temperature rise damage and the temperature reduction damage in each cycle in the reverse direction. As a preferred embodiment of the present invention, the equation for the temperature increase damage is: DH＝1-(1-DT1)(1-DT3); (2) wherein D T1 is the ratio of the number of broken microelements to the total number of the microelements before rock breaking after the 1 st cycle temperature rise, and D T3 is the ratio of the number of broken microelements to the total number of the microelements before rock breaking after the 2 nd cycle temperature rise. As a preferred embodiment of the present invention, the formula of the cooling damage is: DC＝1-(1-DT2)(1-DT4); (3) wherein D T2 is the ratio of the number of broken microelements after the 1 st cycle cooling to the total number of the microelements before the rock breaking, and D T4 is the ratio of the number of broken microelements after the 2 nd cycle cooling to the total number of the microelements before the rock breaking. As a preferred embodiment of the present invention, the damage prediction model is formulated as follows: Wherein D T is damage of rock caused by temperature transformation, epsilon v is volumetric thermal strain, and K, m is weibull distribution scale parameter and shape parameter respectively. As a preferred embodiment of the invention, the system for predicting cyclic damage to the grain-like rock Dan Lengre comprises a memory for storing instructions executable by a processor and a processor for executing the instructions to implement the method for predicting cyclic damage to the grain-like rock Dan Lengre. As a preferred embodiment of the invention, a computer readable medium storing computer program code which, when executed by a processo