# US 2021/0340849 A1 · Determining the integrity of an isolated zone in a wellbore

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- Number: US 2021/0340849 A1
- Document ID: US20210340849A1
- Status: Published application
- Kind: A1
- Application number: 16/866,060
- Filed: 2020-05-04
- Published: 2021-11-04
- Earliest claimed: 2020-05-04
- Assignees: Saudi Arabian Oil Company; Wireless Instrumentation Systems AS
- Applicants: Saudi Arabian Oil Company; Wireless Instrumentation Systems AS
- Inventors: Muhammad Arsalan; Jarl André Fellinghaug; Stian Marius Hansen; Vegard Fiksdal
- Web page: https://patentgrep.com/patent/US20210340849A1

## CPC

- E21B 33/0355: {Control systems, e.g. hydraulic, pneumatic, electric, acoustic, for submerged well heads}
- E21B 43/14: Obtaining from a multiple-zone well
- E21B 33/1208: {characterised by the construction of the sealing or packing means (E21B33/1277 takes precedence)}
- E21B 33/124: Units with longitudinally-spaced plugs for isolating the intermediate space
- E21B 47/06: Measuring temperature or pressure
- E21B 47/008: Monitoring of down-hole pump systems, e.g. for the detection of "pumped-off" conditions
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

A zonal isolation assessment system includes a receiver, production tubing disposed in a wellbore, a zonal isolation assembly, and an assessment assembly. The zonal isolation assembly is fluidically coupled to the production tubing. The zonal isolation assembly includes isolation tubing that flows production fluid from the wellbore to the production tubing, a first sealing element, and a second sealing element to fluidically isolate an internal volume of the isolation tubing from an isolated annulus defined between the isolation tubing and the wall of the wellbore. The assessment assembly includes a first pressure sensor at the internal volume of the isolation tubing configured to sense a first pressure value and a second pressure sensor at the annulus and configured to sense a second pressure value. The assessment assembly transmits to the receiver the first pressure value and the second pressure value to determine the integrity of the zonal isolation assembly.

## Claims

### Claim 1

A zonal isolation assessment system comprising:
a receiver residing at or near a surface of a wellbore;
production tubing configured to be disposed in the wellbore;
a zonal isolation assembly configured to reside downhole of and fluidically coupled to the production tubing, the zonal isolation assembly configured to isolate a zone of the wellbore and comprising:
isolation tubing configured to flow production fluid from the wellbore to the production tubing,
a first sealing element coupled to the isolation tubing, and
a second sealing element coupled to the isolation tubing and disposed downhole of the first sealing element, the first sealing element and the second sealing element configured to be set on a wall of the wellbore to fluidically isolate an internal volume of the isolation tubing from an isolated annulus defined between the isolation tubing and the wall of the wellbore, the annulus extending from the first sealing element to the second sealing element; and
an assessment assembly disposed at least partially inside the isolation tubing and communicatively coupled to the receiver, the assessment assembly comprising,
a first pressure sensor residing at the internal volume of the isolation tubing and configured to sense a first pressure value representing a fluidic pressure of the internal volume, and
a second pressure sensor residing at the annulus and configured to sense a second pressure value representing a fluidic pressure of the annulus, the assessment assembly configured to transmit, to the receiver, the first pressure value and the second pressure value such that the first and second pressure values are usable to determine, based comparing the first pressure value with the second pressure value, a zonal isolation integrity of the zonal isolation assembly.

### Claim 2 (depends on 1)

The system of claim 1, wherein the first pressure value comprises a first set of pressure values sensed by the first pressure sensor over time before and during production, and wherein the second pressure value comprises a second set of pressure values sensed by the second pressure sensor over time before and during production, wherein the first set of pressure values and the second set of pressure values are usable to determine the zonal isolation integrity of the zonal isolation assembly by at least one of: 1) comparing a rate of change over time of the second set of pressure values to a first threshold, the second set of pressure values starting at a point in time in which the first set of pressure values represent the beginning of a drawdown pressure, or 2) comparing a rate of change over time between the first set of pressure values and the second set of pressure values to a second threshold.

### Claim 3 (depends on 2)

The system of claim 2, wherein the first threshold represents a percentage of the drawdown pressure, and wherein the drawdown pressure represents a change in pressure at the internal volume as the wellbore enters a flowing condition.

### Claim 4 (depends on 3)

The system of claim 3, wherein the first threshold represent 5% or less of the drawdown pressure, and wherein the first and second pressure values are usable to determine low isolation integrity when the rate of change over time of the second set of pressure values is equal to or larger than the threshold.

### Claim 5 (depends on 1)

The system of claim 1, wherein the assessment assembly is configured to continuously or generally continuously transmit real-time data to the receiver, the real-time data representing a first set of pressure values sensed by the first pressure sensor over time before and during production and a second set of pressure values sensed by the second pressure sensor over time before and during production, the first and second set of pressure values usable to determine the zonal isolation integrity in or near real-time.

### Claim 6 (depends on 1)

The system of claim 1, wherein the zonal isolation assembly is configured to be permanently set on the wall of the wellbore to isolate the zone of the wellbore during production.

### Claim 7 (depends on 1)

The system of claim 1, wherein the isolation tubing is disposed at an open hole section of the wellbore, the isolated zone comprising a region of the open hole section isolated by the first sealing element and the second sealing element set on a wall of the open hole section of the wellbore.

### Claim 8 (depends on 1)

The system of claim 1, wherein the receiver is communicatively coupled to a processor configured to determine, based on a rate of change of the first pressure value and the second pressure value, a third value representing a leakage percentage, and wherein the processor is configured to determine a level of isolation integrity based on comparing the leakage percentage to a leakage percentage threshold.

### Claim 9 (depends on 1)

The system of claim 1, wherein the assessment assembly is releasably coupled to and disposed inside the isolation tubing, and wherein the assessment assembly comprises a fluid pathway configured to receive production fluid from the isolation tubing at the internal volume and flow the production fluid to the first pressure sensor disposed along the fluid pathway.

### Claim 10 (depends on 9)

The system of claim 9, wherein the assessment assembly is configured to be retrieved from the assessment assembly by a retrieving tool run on wireline, slick line, or coiled tubing.

### Claim 11 (depends on 9)

The system of claim 9, wherein the assessment assembly comprises a first housing configured to house and protect circuitry and a battery system configured to power electric components of the circuitry, the circuitry configured to receive the first pressure value and the second pressure value and configured to transmit the first pressure value and the second pressure value to the receiver.

### Claim 12 (depends on 11)

The system of claim 11, wherein the assessment assembly comprises a second housing configured to house and protect at least a portion of an electric turbine assembly and a pressure compensator, the electric turbine assembly comprising a turbine axially coupled to a rotating shaft and configured to rotate under fluidic pressure of production fluid flowing through the turbine, the rotating shaft coupled to an electric generator configured to produce electricity through rotation of the shaft, the electric generator electrically coupled to and configured to charge batteries of the battery system.

### Claim 13 (depends on 12)

The system of claim 12, wherein the assessment assembly comprises a turbine housing and an engagement assembly releasably attached to the isolation tubing, the first housing and the second housing forming a tubular body attached to and disposed between the turbine housing and the engagement assembly, the tubular body forming an annulus with a wall of the isolation tubing in which at least a portion of the fluid pathway is defined.

### Claim 14

An assessment assembly comprising:
isolation tubing configured to be disposed in a wellbore downhole of production tubing, the isolation tubing configured to flow production fluid from the wellbore to the production tubing,
a first sealing element coupled to the isolation tubing,
a second sealing element coupled to the isolation tubing and disposed downhole of the first sealing element, the first sealing element and the second sealing element configured to be set on a wall of the wellbore to fluidically isolate an internal volume of the isolation tubing from an isolated annulus defined between the isolation tubing and the wall of the wellbore, the isolated annulus extending from the first sealing element to the second sealing element,
a first pressure sensor residing at the internal volume of the isolation tubing, the first pressure sensor communicatively coupled and configured to transmit first pressure information to a receiver at or near a surface of the wellbore, and
a second pressure sensor residing at the annulus, the second pressure sensor communicatively coupled and configured to transmit second pressure information to the receiver such that the first pressure information and the second pressure information is usable to determine a zonal isolation integrity of the isolation tubing.

### Claim 15 (depends on 14)

The assessment assembly of claim 14, wherein the first pressure sensor and the second pressure sensor are coupled to an autonomous assessment assembly releasably coupled to the isolation tubing, the autonomous assessment assembly comprising an energy harvesting system configured to harvest energy from the production fluid to power electronics electrically coupled to the first and second pressure sensor.

### Claim 16 (depends on 14)

The assessment assembly of claim 14, wherein the assessment assembly is configured to continuously or generally continuously transmit real-time data to the receiver, the real-time data representing a first set of pressure values sensed by the first pressure sensor over time before and during production and a second set of pressure values sensed by the second pressure sensor over time before and during production, the first and second set of pressure values usable to determine the zonal isolation integrity.

### Claim 17 (depends on 14)

The assessment assembly of claim 14, wherein the isolation tubing is configured to be permanently set on the wall of the wellbore to permanently isolate a zone of the wellbore during production.

### Claim 18 (depends on 17)

The assessment assembly of claim 17, wherein the isolation tubing is disposed at an open hole section of the wellbore, the isolated annulus comprising a region of the open hole section and isolated by the first sealing element and the second sealing element set on a wall of the open hole section of the wellbore.

### Claim 19

A method comprising:
receiving, by a receiver at or near a surface of a wellbore, a first pressure value and a second pressure value from a zonal isolation assembly disposed downhole of production tubing, the zonal isolation assembly comprising 1) isolation tubing, 2) a first sealing element coupled to the isolation tubing, 3) a second sealing element coupled to the isolation tubing and disposed downhole of the first sealing element, the first sealing element and the second sealing element configured to be set on a wall of the wellbore to fluidically isolate an internal volume of the isolation tubing from an isolated annulus defined between the isolation tubing and the wall of the wellbore, 4) a first pressure sensor residing at the internal volume of the isolation tubing and configured to sense the first pressure value, and 5) a second pressure sensor residing at the annulus and configured to sense the second pressure value; and
determining, based on comparing the first pressure value to the second pressure value, a third value representing a zonal isolation integrity of the zonal isolation assembly.

### Claim 20 (depends on 19)

The method of claim 19, wherein receiving the first value comprises receiving a first set of pressure values sensed by the first pressure sensor over time before and during production, and wherein receiving the second value comprises receiving a second set of pressure values sensed by the second pressure sensor over time before and during production, and wherein determining the third value comprises determining the third value based on 1) comparing a rate of change over time of the second set of pressure values to a first threshold, the second set of pressure values starting at a point in time in which the first set of pressure values represent the beginning of a drawdown pressure, or 2) comparing a rate of change over time between the first set of pressure values and the second set of pressure values to a second threshold.