US 2026/0309606 A1Published application

Method for measuring downhole holdup, and method for determining downhole fluid interface and geometric distribution

AssigneeChina University of Petroleum (East China)

InventorXuanhua ZHANG

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Abstract

The present disclosure relates to a method for measuring downhole holdup, and a method for determining downhole fluid interface and geometric distribution, which belongs to the field of oil and gas exploration technology. The method for measuring downhole holdup uses a plurality of tuning forks distributed on the flow cross-section to achieve the oil-water determination by comparing the fluid density collected by tuning forks with a preset oil-water density discrimination threshold. The time proportion of oil/water collected by the tuning forks is used to characterize downhole fluid holdup. This method offers advantages such as good versatility, high measurement efficiency, and high resolution. The method for measuring downhole fluid interface uses a plurality of tuning forks distributed on the flow cross-section to achieve the oil-water determination. Based on the oil-water alternating switching phenomenon, oil-water interface points are identified, and the oil-water interface of the horizontal well is determined.

Claims10

Dependent claims

A method for measuring a downhole holdup, employing a distributed tuning fork downhole fluid holdup measuring instrument for a measurement, wherein the distributed tuning fork downhole fluid holdup measuring instrument comprises a housing and at least eight tuning forks arranged at equal phase intervals along a circumferential direction of the housing, each tuning fork is connected to the housing via a corresponding telescopic arm, the telescopic arms corresponding to the tuning forks have different lengths to make a plurality of tuning forks distributed in a multi-turn ring shape relative to the axis of the housing after the telescopic arm is deployed;

the method for measuring comprises the following steps:
S11, placing the distributed tuning fork downhole fluid holdup measuring instrument with the telescopic arms in a retracted state downhole along a wellbore, and deploying the telescopic arms so that a plurality of tuning forks are located at different positions of a flow cross-section to be measured downhole;
S12, using each tuning fork of the distributed tuning fork downhole fluid holdup measuring instrument to continuously collect a fluid density flowing through the position of the tuning fork, and when the fluid density collected by the tuning fork is greater than a preset oil-water density discrimination threshold, determining that the fluid currently flowing through the position of the tuning fork is water, otherwise determining it to be oil;
and
S13, according to formulas (1-1) and (1-2), calculating a local water holdup and a local oil holdup at the position of each tuning fork, respectively, and according to formulas (1-3) and (1-4), calculating a total water holdup and a total oil holdup corresponding to the flow cross-section to be measured, respectively;
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where i=1, 2, 3 . . . n;
n is a number of tuning forks, dimensionless;
yw(i) is a local water holdup at the position of an ith tuning fork, %;
yo(i) is a local oil holdup at the position of the ith tuning fork, %;
Σtw(i) is a cumulative total time that the fluid density collected by the ith tuning fork is greater than the preset oil-water density discrimination threshold, s;
Σto(i) is a cumulative total time that the fluid density collected by the ith tuning fork is less than or equal to the preset oil-water density discrimination threshold, s;
yw is a total water holdup of the flow cross-section to be measured, %;
yo is a total oil holdup of the flow cross-section to be measured, %.

132 more elements

A method for determining a downhole fluid interface, applied to a horizontal well, employing a distributed tuning fork downhole fluid holdup measuring instrument to determine a fluid interface of the horizontal well, the distributed tuning fork downhole fluid holdup measuring instrument comprises a housing and at least eight tuning forks arranged at equal phase intervals along a circumferential direction of the housing, each tuning fork is connected to the housing via a corresponding telescopic arm, the telescopic arms corresponding to the tuning forks have different lengths to make a plurality of tuning forks distributed in a multi-turn ring shape relative to the axis of the housing after the telescopic arm is deployed;

the method for determining a downhole fluid interface comprises the following steps:
S21, horizontally placing the distributed tuning fork downhole fluid holdup measuring instrument with the telescopic arms in a retracted state into a measurement position of the horizontal well along a wellbore, and deploying the telescopic arms so that a plurality of tuning forks are located at different positions of a flow cross-section at the current measurement position;
S22, using each tuning fork of the distributed tuning fork downhole fluid holdup measuring instrument to continuously collect a fluid density flowing through the position of the tuning fork, and when the fluid density collected by the tuning fork is greater than a preset oil-water density discrimination threshold, determining that the fluid currently flowing through the position of the tuning fork is water, otherwise determining it to be oil;
in a preset collection time, when a fluid flowing through a position of a certain tuning fork is continuously and alternately switched between water and oil for many times, identifying the position of the tuning fork as an oil-water interface point of a flow cross-section at a current measurement position, and identifying at least three oil-water interface points on the flow cross-section at the current measurement position;
S23, retracting the telescopic arms and moving the distributed tuning fork downhole fluid holdup measuring instrument to a next adjacent measurement position along a horizontal direction, deploying the telescopic arms so that a plurality of tuning forks are located at different positions of the flow cross-section at the current measurement position, and repeating step S22;
and
S24, repeating step S23, determining the oil-water interface points on the flow cross-section at several different measurement positions in the horizontal well, connecting the oil-water interface points and performing a surface fitting to obtain the oil-water interface of the horizontal well.

4 more elements

A method for determining a downhole fluid geometric distribution, applied to a vertical well, employing a distributed tuning fork downhole fluid holdup measuring instrument to determine a geometric distribution of the vertical well, the distributed tuning fork downhole fluid holdup measuring instrument comprises a housing and at least eight tuning forks arranged at equal phase intervals along a circumferential direction of the housing, each tuning fork is connected to the housing via a corresponding telescopic arm, the telescopic arms corresponding to the tuning forks have different lengths to make a plurality of tuning forks distributed in a multi-turn ring shape relative to the axis of the housing after the telescopic arm is deployed;

the method for determining a downhole fluid geometric distribution comprises the following steps:
S31, vertically placing the distributed tuning fork downhole fluid holdup measuring instrument with the telescopic arms in a retracted state into the vertical well along a wellbore, and deploying the telescopic arms so that a plurality of tuning forks are located at different positions of the flow cross-section to be measured of the vertical well;
S32, using each tuning fork of the distributed tuning fork downhole fluid holdup measuring instrument to continuously collect a fluid density flowing through the position of the tuning fork, and when the fluid density collected by the tuning fork is greater than a preset oil-water density discrimination threshold, determining that the fluid currently flowing through the position of the tuning fork is water, otherwise determining it to be oil;
S33, according to formula (2-1), calculating a local oil holdup at the position of each tuning fork;
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where i=1, 2, 3 . . . n;
n is a number of tuning forks, dimensionless;
yo(i) is a local oil holdup at the position of an ith tuning fork, %;
Σtw(i) is a cumulative total time that the fluid density collected by the ith tuning fork is greater than the preset oil-water density discrimination threshold, s;
Σto(i) is a cumulative total time that the fluid density collected by the ith tuning fork is less than or equal to the preset oil-water density discrimination threshold, s;
S34, drawing a circular area to represent a flow cross-section to be measured of the vertical well, determining a corresponding position of each tuning fork in the circular area according to the position of each tuning fork on the flow cross-section to be measured, and for all tuning forks with a local oil holdup not being zero, drawing a circular oil bubble at the corresponding position of the tuning fork in the circular area, so as to obtain a fluid geometric distribution diagram corresponding to the flow cross-section;
wherein an area of the circular oil bubble at the position corresponding to each tuning fork in the circular area is calculated according to formula (2-2);
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where Si is an area of the circular oil bubble at the position of the ith tuning fork, and S is an area of the circular area.

67 more elements

Dependencies are inferred from the claim text.

Facts

Application: 19/682,598Filed 20 May 2026
Priority: CN 202610236572.228 Feb 2026
Published: 8 Oct 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G01N 9/002
Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity: using variation of the…
E21B 49/0875
Well testing, e.g. testing for reservoir productivity or formation parameters: determining specific fluid parameters
G01N 33/2823
Oils , i.e. hydrocarbon liquids: raw oil, drilling fluid or polyphasic mixtures
G01N 33/2847
Specific substances contained in the oils or fuels: water in oils