CN-115203872-B - Method for determining pollution degree near well bore based on skin factor of thermodynamic parameter

CN115203872BCN 115203872 BCN115203872 BCN 115203872BCN-115203872-B

Abstract

The invention relates to a method for determining pollution degree near a shaft based on a skin factor of a thermodynamic parameter, which comprises the steps of measuring the shaft parameter and the thermodynamic parameter, establishing a pressure relation equation near the shaft according to the shaft parameter and the thermodynamic parameter, establishing a temperature relation equation near the shaft according to the shaft parameter and the thermodynamic parameter, solving the skin factor according to the pressure relation equation and the temperature relation equation, and determining the pollution degree near the shaft based on the skin factor. According to the invention, under the condition of known thermodynamic parameters, the skin factor can be rapidly calculated from the thermodynamic angle, fitting of a well test curve is not needed, well test interpretation efficiency is improved to a certain extent, calculation steps are simple, and the method is rapid.

Inventors

ZHANG LIJUN
ZHAO LIN
YANG RENFENG
PENG SHIQIANG
Jiao Yujia
LI NAN
Tian Tafeng
WANG TAICHAO
XIE HAOJUN
BAI YUTING

Assignees

中海石油(中国)有限公司
中海石油（中国）有限公司北京研究中心

Dates

Publication Date: 20260505
Application Date: 20220720

Claims (3)

1. A method of determining contamination levels near a wellbore based on skin factors of thermodynamic parameters, comprising: measuring wellbore parameters and thermodynamic parameters; establishing a near-wellbore pressure relation equation according to the wellbore parameters and the thermodynamic parameters; establishing a near-wellbore temperature relation equation according to the wellbore parameters and the thermodynamic parameters; Solving a skin factor according to the pressure relation equation and the temperature relation equation, and determining a contamination level near the wellbore based on the skin factor; Establishing a near-wellbore pressure relation equation according to the wellbore parameters and the thermodynamic parameters, wherein the near-wellbore pressure relation equation comprises the following steps: (1) Wherein, the Representing the bottom hole pressure, pa; represents the radius of the well bore, m; Represents the epidermal factor, dimensionless; representing the pressure, Representing the radius; establishing a near wellbore temperature relationship equation from the wellbore parameter and the thermodynamic parameter includes: Calculating heat flux of a shaft unit length: (2) according to rami and wilkini, the overall heat conductivity is defined: (3) considering the influence of the surface factors on the effective well diameter, calculating the comprehensive heat conductivity coefficient between the shaft and the stratum during oil pipe production: (4) Calculating the comprehensive heat conductivity coefficient between the shaft and the stratum during casing production: (5) the temperature relationship in the vicinity of the well bore obtained by combining the formula (2) and the formula (3) is: (6) In the formula, Representing the bottom hole temperature, K; represents the radius of the well bore, m; the inner diameter of the oil pipe is represented by m; The outer diameter of the oil pipe is represented by m; represents the inner diameter of the sleeve, m; Represents the outer diameter of the sleeve, m; Represents the epidermal factor, dimensionless; Represents the heat conductivity coefficient of the stratum, w/(m.K); Represents the annular heat conductivity coefficient, w/(m.K); The thermal conductivity coefficient of the cement sheath is represented by w/(m.K); Representing the comprehensive heat conductivity coefficient between a shaft and a stratum, wherein w/(m2.K); Represents heat flux, w/m 2 ; Representing temperature; Representing the radius; Solving a skin factor from the pressure relationship equation and the temperature relationship equation includes: Can be obtained according to the formulas (1) and (6) (7) Joule Thomson coefficient is defined as (8) In the formula, Represents the Joule Thomson coefficient, K/Pa; Thus formula (5) can be written as (9) The epidermal factor can be expressed as (10) Substituting the formula (4) and the formula (5) into the formula (10) respectively to obtain the expression of the epidermal factor: during oil pipe production, the expression of the surface factor is (11) When the sleeve is produced, the expression of the surface factor is (12)。
2. The method of determining contamination level near a wellbore based on a skin factor of thermodynamic parameters of claim 1, wherein the wellbore parameters comprise at least one of the group consisting of wellbore radius, tubing inner diameter, tubing outer diameter, casing inner diameter, and casing outer diameter.
3. The method of determining contamination level near a wellbore of claim 1, wherein the thermodynamic parameter comprises at least one of the group consisting of annulus thermal conductivity, cement sheath thermal conductivity, and formation thermal conductivity.

Description

Method for determining pollution degree near well bore based on skin factor of thermodynamic parameter Technical Field The invention relates to the technical field of well testing, in particular to a method for determining pollution degree near a shaft by using a skin factor based on thermodynamic parameters. Background Contamination occurs near the wellbore due to imperfections in perforation opening during drilling, the extent of contamination being generally expressed in terms of skin factors. In contaminated areas, changes in permeability occur in near wellbore zones due to skin factors, and likewise thermodynamic parameters (e.g., thermal conductivity, etc.) are affected. At present, the pressure recovery well test is a common method for calculating the skin factor, and establishing the relationship between the skin factor and the thermodynamic parameter can become a new idea for calculating the skin factor. The magnitude of the skin factor is often used as a basis for whether or not to perform stimulation to increase the productivity of a single well. The determination of the skin factor becomes particularly important to ensure proper production of the well. The surface factors are calculated from the thermodynamic angle, fitting of a well test curve is not needed, and well test interpretation efficiency can be improved to a certain extent. The well test interpretation can also be combined, so that the calculation result of the surface factor is more accurate. Disclosure of Invention Aiming at the problems, the invention aims to provide a method for determining the pollution degree near a shaft by using a skin factor based on thermodynamic parameters, which aims to solve the problems of interpretation and calculation of the skin factor and the like. In order to achieve the above purpose, the present invention adopts the following technical scheme: a method of determining contamination levels near a wellbore based on skin factors of thermodynamic parameters, comprising: measuring wellbore parameters and thermodynamic parameters; establishing a near-wellbore pressure relation equation according to the wellbore parameters and the thermodynamic parameters; establishing a near-wellbore temperature relation equation according to the wellbore parameters and the thermodynamic parameters; A skin factor is solved according to the pressure relationship equation and the temperature relationship equation, and a contamination level near the wellbore is determined based on the skin factor. The wellbore parameters include at least one of the group consisting of wellbore radius, tubing inner diameter, tubing outer diameter, casing inner diameter, and casing outer diameter. The thermodynamic parameters include at least one of the group consisting of annulus thermal conductivity, cement sheath thermal conductivity, and formation thermal conductivity. Establishing a near-wellbore pressure relation equation according to the wellbore parameters and the thermodynamic parameters, wherein the near-wellbore pressure relation equation comprises the following steps: (1) Wherein, the Representing the bottom hole pressure, pa; represents the radius of the well bore, m; Represents the epidermal factor, dimensionless; representing the pressure, Representing the radius. Establishing a near wellbore temperature relationship equation from the wellbore parameter and the thermodynamic parameter includes: Calculating heat flux of a shaft unit length: (2) The overall heat transfer coefficient is defined in terms of Ramey and Weilhaite (Willhite): (3) considering the influence of the surface factors on the effective well diameter, calculating the comprehensive heat conductivity coefficient between the shaft and the stratum during oil pipe production: (4) Calculating the comprehensive heat conductivity coefficient between the shaft and the stratum during casing production: (5) the temperature relationship in the vicinity of the well bore obtained by combining the formula (2) and the formula (3) is: (6) In the formula, Representing the bottom hole temperature, K; represents the radius of the well bore, m; the inner diameter of the oil pipe is represented by m; The outer diameter of the oil pipe is represented by m; represents the inner diameter of the sleeve, m; Represents the outer diameter of the sleeve, m; Represents the epidermal factor, dimensionless; Represents the heat conductivity coefficient of the stratum, w/(m.K); Represents the annular heat conductivity coefficient, w/(m.K); The thermal conductivity coefficient of the cement sheath is represented by w/(m.K); Representing the comprehensive heat conductivity coefficient between a shaft and a stratum, wherein w/(m2.K); Represents heat flux, w/m 2; Representing temperature; Representing the radius. Solving a skin factor from the pressure relationship equation and the temperature relationship equation includes: Can be obtained according to the formulas (1) and (6) (7) Jo