Determining depth of loss zones in subterranean formations

Patent metadata

Field	Value
Publication number	US-2016341031-A1
Application number	US-201414769628-A
Country	US
Kind code	A1
Filing date	Nov 26, 2014
Priority date	Nov 26, 2014
Publication date	Nov 24, 2016
Grant date	—

Abstract

Methods of locating a loss zone in a wellbore in a subterranean formation including determining a calculated wellhead pressure, calculating a wellhead pressure differential, calculating a flow rate loss, estimating a loss zone depth, determining a modified calculated wellhead pressure, and calculating a modified wellhead pressure differential until the modified wellhead pressure differential corresponds to a loss zone location in the wellbore.

First claim

The invention claimed is:

1 . A method of locating a loss zone in a subterranean formation comprising:
(a) providing a wellbore in the subterranean formation having a tubular therein, wherein an annulus is formed between the tubular and a face of the wellbore; (b) introducing a treatment fluid into the wellbore through the tubular and displacing the treatment fluid up through the annulus; (c) logging real-time measurements during introducing and displacing the treatment fluid, the real-time measurements selected from the group consisting of actual wellhead pressure (AWP), treatment fluid inlet density (ρ i ), inlet flow rate ({dot over (Q)} i ), outlet flow rate ({dot over (Q)} o ), treatment fluid inlet viscosity (μ i ), and any combination thereof; (d) determining a calculated wellhead pressure (CWP) based on the real-time measurements of step (c); (e) calculating a wellhead pressure differential (ΔWP) based on Formula 1: ΔWP=|CWP−AWP|; (f) calculating a flow rate loss ({dot over (Q)} loss ) based on Formula 2: {dot over (Q)} loss ={dot over (Q)} i −{dot over (Q)} o ; (g) estimating a loss zone depth (d est ) at a depth along the wellbore; (h) determining a modified calculated wellhead pressure (CWP mod ) based on hydraulic calculations, wherein the flow rate loss ({dot over (Q)} loss ) and the estimated loss zone depth (d lz ) are used as inputs; (i) calculating a modified wellhead pressure differential (ΔWP mod ); and (j) repeating steps (g) through (i) until the modified wellhead pressure differential (ΔWP mod ) is in the range of 0 to a user defined maximum, whereby the estimated loss zone depth (d est ) substantially corresponds to a loss zone location (d lz ) in the wellbore.

2 . The method of claim 1 , wherein the treatment fluid is selected from the group consisting of a non-aqueous fluid, an aqueous fluid, an aqueous-miscible fluid, a water-in-oil emulsion, an oil-in-water emulsion, and any combination thereof.

3 . The method of claim 1 , wherein the tubular is selected from the group consisting of a casing string, a flexible tubing, an inflexible tubing, a drill string, and any combination thereof.

4 . The method of claim 1 , wherein the hydraulic calculations of step (h) are performed using hydraulic simulation software.

5 . The method of claim 1 , wherein the user defined maximum is less than about 50,000.

6 . The method of claim 1 , further comprising a wellhead with the tubular extending therefrom and into the wellbore, and a pump fluidly coupled to the tubular.

7 . A method of locating a loss zone in a subterranean formation comprising:
(a) providing a wellbore in the subterranean formation having a tubular therein, wherein an annulus is formed between the tubular and a face of the wellbore; (b) introducing a treatment fluid into the wellbore through the tubular and displacing the treatment fluid up through the annulus; (c) logging real-time measurements during introducing and displacing the treatment fluid, the real-time measurements selected from the group consisting of actual wellhead pressure (AWP), treatment fluid inlet density (ρ i ), inlet flow rate ({dot over (Q)} i ), outlet flow rate ({dot over (Q)} o ), treatment fluid inlet viscosity (μ 1 ), and any combination thereof; (d) determining a calculated wellhead pressure (CWP) based on the real-time measurements of step (c); (e) calculating a wellhead pressure differential (ΔWP) based on Formula 1: ΔWP=|CWP−AWP|; (f) calculating a flow rate loss ({dot over (Q)} loss ) based on Formula 2: {dot over (Q)} loss ={dot over (Q)} i −{dot over (Q)} o ; (g) estimating a loss zone depth (d est ) at a depth along the wellbore; (h) determining a modified calculated wellhead pressure (CWP mod ) based on hydraulic calculations, wherein the flow rate loss ({dot over (Q)} loss ) and the estimated loss zone depth (d lz ) are used as inputs; (i) calculating a modified wellhead pressure differential (ΔWP mod ); and (j) repeating steps (g) through (i) until the modified wellhead pressure differential (ΔWP mod ) is in the range of 0 to a user defined maximum, whereby the estimated loss zone depth (d est ) substantially corresponds to a loss zone location (d lz ) in the wellbore; and (k) performing a remedial operation to at least partially seal the loss zone location (d lz ) in the wellbore.

8 . The method of claim 7 , wherein the remedial operation is selected from the group consisting of ceasing operations, removing the treatment fluid from the wellbore, reformulating the treatment fluid, introducing a loss circulation pill into the wellbore, reducing the inlet flow rate ({dot over (Q)} i ), increasing the inlet flow rate ({dot over (Q)} i ), and any combination thereof.

9 . The method of claim 7 , wherein the treatment fluid is selected from the group consisting of a non-aqueous fluid, an aqueous fluid, an aqueous-miscible fluid, a water-in-oil emulsion, an oil-in-water emulsion, and any combination thereof.

10 . The method of claim 7 , wherein the tubular is selected from the group consisting of a casing string, a flexible tubing, an inflexible tubing, a drill string, and any combination thereof.

11 . The method of claim 7 , wherein the hydraulic calculations of step (h) are performed using hydraulic simulation software.

12 . The method of claim 7 , wherein the user defined maximum is less than about 50,000.

13 . The method of claim 7 , further comprising a wellhead with the tubular extending therefrom and into the wellbore, and a pump fluidly coupled to the tubular.

14 . A method of locating a loss zone in a subterranean formation comprising:
(a) providing a first wellbore in the subterranean formation having a tubular therein, wherein an annulus is formed between the tubular and a face of the wellbore,
wherein subterranean formation comprises an oilfield;
(b) introducing a first treatment fluid into the first wellbore through the tubular and displacing the first treatment fluid up through the annulus; (c) logging real-time measurements during introducing and displacing the first treatment fluid, the real-time measurements selected from the group consisting of actual wellhead pressure (AWP), first treatment fluid inlet density (ρ i ), inlet flow rate ({dot over (Q)} i ), outlet flow rate ({dot over (Q)} o ), treatment fluid inlet viscosity (μ 1 ), and any combination thereof; (d) determining a calculated wellhead pressure (CWP) based on the real-time measurements of step (c); (e) calculating a wellhead pressure differential (ΔWP) based on Formula 1: ΔWP=|CWP−AWP|; (f) calculating a flow rate loss ({dot over (Q)} loss ) based on Formula 2: {dot over (Q)} loss ={dot over (Q)} i −{dot over (Q)} o ; (g) estimating a loss zone depth (d est ) at a depth along the wellbore; (h) determining a modified calculated wellhead pressure (CWP mod ) based on hydraulic calculations, wherein the flow rate loss ({dot over (Q)} loss ) and the estimated loss zone depth (d lz ) are used as inputs; (i) calculating a modified wellhead pressure differential (ΔWP mod ); and (j) repeating steps (g) through (i) until the modified wellhead pressure differential (ΔWP mod ) is in the range of 0 to a user defined maximum, whereby the estimated loss zone depth (d est ) substantially corresponds to a loss zone location (d lz ) in the first wellbore; (k) establishing an oilfield loss zone location (d field lz ) for the oilfield that is equivalent to the location of the loss zone in the wellbore; (l) providing a second wellbore in the subterranean formation having the oilfield loss zone location (d field lz ) therein; (m) performing a preventative o

Assignees

• Halliburton Energy Services Inc

Inventors

• Yerubandi Krishna Babu
• Savery Mark Ryan

Classifications

• E21B47/06

  Measuring temperature or pressure · CPC title

• E21B33/03

  Well heads; Setting-up thereof · CPC title

• E21B47/10 Primary

  Locating fluid leaks, intrusions or movements · CPC title

• E21B33/13

  Methods or devices for cementing, for plugging holes, crevices or the like · CPC title

• E21B47/04 Primary

  Measuring depth or liquid level · CPC title