# US 2016/0258246 A1 · Methods for formulating a cement slurry for use in a subterranean salt formation

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- Number: US 2016/0258246 A1
- Document ID: US20160258246A1
- Status: Published application
- Kind: A1
- Application number: 14/429,919
- Filed: 2014-05-30
- Published: 2016-09-08
- Earliest claimed: 2014-05-30
- Assignees: Halliburton Energy Services, Inc.
- Applicants: Halliburton Energy Services, Inc.
- Inventors: Siva Rama Krishna Jandhyala; Krishna Ravi; Sandip Prabhakar Patil; Krishna Babu Yerubandi; Abhimanyu Deshpande; Yogesh Ramesh Barhate; Rahul Chandrakanth Patil
- Web page: https://patentgrep.com/patent/US20160258246A1

## CPC

- E21B 33/14: for cementing casings into boreholes
- C04B 7/361: {Condition or time responsive control in hydraulic cement manufacturing processes (controlling or regulating in general G05; F27B7/42 takes precedence)}
- C09K 8/40: Spacer compositions, e.g. compositions used to separate well-drilling from cementing masses
- C09K 8/42: Compositions for cementing, e.g. for cementing casings into boreholes; Compositions for plugging, e.g. for killing wells (compositions for plastering C09K8/50)
- E21B 33/13: Methods or devices for cementing, for plugging holes, crevices or the like
- E21B 49/003: {by analysing drilling variables or conditions (E21B49/005 takes precedence; systems specially adapted for monitoring a plurality of drilling variables or conditions E21B44/00)}
- G01V 1/40: specially adapted for well-logging
- G06F 9/455: Emulation; Interpretation; Software simulation, e.g. virtualisation or emulation of application or operating system execution engines
- E21B 47/08: Measuring diameters or related dimensions at the borehole
- E21B 49/00: Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

Methods of formulating a cement slurry for use in a subterranean salt formation, including methods for formulating a cement slurry capable of providing long-term zonal isolation within a subterranean salt formation. The methods also take into account the effects of treatment fluids on the cement slurry, such as drilling fluids, spacer fluids, flush fluids, or other relevant fluids used to perform a subterranean formation operation.

## Claims

### Claim 1

A method comprising:
(a) calculating a theoretical first wellbore radius in a subterranean salt formation having a treatment fluid therein based on salt creep analysis in the presence of formation-treatment fluid;
(b) calculating a theoretical second wellbore radius in the subterranean salt formation during a cementing operation with a proposed cement slurry based on salt creep analysis in the presence of formation-cement slurry,
wherein the cementing operation involves forming a proposed cement sheath within the wellbore, and wherein the proposed cement sheath must withstand a wellbore load to prevent failure of the cement sheath in the wellbore;
(c) determining experimentally a rheology of the proposed cement slurry versus salt dissolution curve;
(d) determining experimentally and based on a convection-diffusion equation a salt dissolution versus flow rate curve;
(e) calculating a theoretical final wellbore radius in the subterranean salt formation based on the theoretical first wellbore radius, the theoretical second wellbore radius, and salt dissolution after forming the proposed cement sheath;
(f) determining a rheology of the proposed cement slurry versus flow rate curve;
(g) calculating theoretically whether the proposed cement sheath is capable of withstanding the wellbore load by calculating theoretical thermal and thermo-mechanical properties of the proposed cement slurry based on salt creep analysis in the presence of formation-cement sheath;
(h) determining experimentally whether the proposed cement sheath is capable of withstanding the wellbore load based on an ultrasonic cement analyzer test and actual thermal and thermo-mechanical properties of the proposed cement slurry after salt dissolution;
(i) calculating theoretically a theoretical pump time and a theoretical pump pressure for the treatment fluid and the proposed cement slurry based on a computational fluid dynamics model,
wherein the theoretical pump pressure for the treatment fluid and the proposed cement slurry is between a pore pressure and a fracture gradient of the subterranean salt formation, and
wherein the theoretical pump time for the treatment fluid and the proposed cement slurry is such that the proposed cement slurry will theoretically permit formation of the proposed cement sheath in the wellbore without substantial premature curing;
(j) determining experimentally whether the theoretical pumping time for the treatment fluid and the proposed cement slurry will permit formation of the proposed cement sheath in the wellbore without substantial premature curing based on a thickening time test of the proposed cement slurry;
(k) performing steps (g)-(h) before steps (i)-(j), or
performing steps (i)-(j) before steps (g)-(h);
(l) establishing a final cement slurry, a final pumping pressure and time for the treatment fluid, and a final pumping pressure and time for the cement slurry;
(m) performing a wellbore operation with the treatment fluid using the final pumping time and pressure for the treatment fluid; and
(n) performing the cementing operation with the final cement slurry using the final pumping time and pressure for the final cement slurry.

### Claim 2 (depends on 1)

The method of claim 1, wherein step (k) comprises performing steps (g)-(h) before steps (i)-(j), and
further comprising manipulating the proposed cement slurry after at least one of:
step (g), and repeating steps (b)-(g) until the proposed cement sheath based on the proposed cement slurry that has been manipulated is theoretically capable of withstanding the wellbore load,
step (h), and repeating steps (b)-(h) until the proposed cement sheath based on the proposed cement slurry that has been manipulated is experimentally capable of withstanding the wellbore load,
step (i), and repeating steps (b)-(i) until the theoretical pumping pressure for the treatment fluid and the proposed cement slurry that has been manipulated is theoretically between the pore pressure and the fracture gradient of the subterranean salt formation and the theoretical pumping time for the treatment fluid and the proposed cement slurry that has been manipulated theoretically permits formation of the proposed cement sheath with the proposed cement slurry that has been manipulated in the wellbore without substantial premature curing, and
step (j), and repeating steps (b)-(j) until the theoretical pumping time experimentally permits formation of the proposed cement sheath in the wellbore with the proposed cement slurry that has been manipulated without substantial premature curing.

### Claim 3 (depends on 1)

The method of claim 1, wherein step (k) comprises performing steps (i)-(j) before steps (g)-(h), and
further comprising manipulating the proposed cement slurry after at least one of:
step (i), and repeating steps (b)-(f) and (i) until the theoretical pumping pressure for the treatment fluid and the proposed cement slurry that has been manipulated is theoretically between the pore pressure and the fracture gradient of the subterranean salt formation and the theoretical pumping time for the treatment fluid and the proposed cement slurry that has been manipulated theoretically permits formation of the proposed cement sheath with the proposed cement slurry that has been manipulated in the wellbore without substantial premature curing,
step (j), and repeating steps (b)-(f) and (i)-(j) until the theoretical pumping time experimentally permits formation of the proposed cement sheath in the wellbore with the proposed cement slurry that has been manipulated without substantial premature curing,
step (g), and repeating steps (b)-(f), (i)-(j), and (g) until the proposed cement sheath based on the proposed cement slurry that has been manipulated is theoretically capable of withstanding the wellbore load, and
step (h), and repeating steps (b)-(f), (i)-(j), and (g)-(h) until the proposed cement sheath based on the proposed cement slurry that has been manipulated is experimentally capable of withstanding the wellbore load.

### Claim 4 (depends on 1)

The method of claim 1, wherein the computational fluid dynamics model of step (i) is used to determine the theoretical pump time and pressure of the treatment fluid and the proposed cement slurry based on: a flow rate of the treatment fluid, a flow rate of the proposed cement slurry, rheology parameters of the treatment fluid, rheology parameters of the proposed cement slurry, a standoff profile, and the theoretical final wellbore radius.

### Claim 5 (depends on 4)

The method of claim 4, wherein at least one of the flow rate of the treatment fluid and the flow rate of the cement slurry are manipulated and step (i) is repeated.

### Claim 6 (depends on 4)

The method of claim 4, wherein the rheology parameters of the treatment fluid and the rheology parameters of the proposed cement slurry are selected from the group consisting of plastic viscosity, Bingham model yield point, Herschel-Bulkley model parameters, and any combination thereof.

### Claim 7 (depends on 1)

The method of claim 1, wherein the theoretical thermal and thermo-mechanical properties of the proposed cement are calculated based on at least one of thermal conductivity, thermal diffusivity, tensile strength, compressive strength, hydration volume change, Young's modulus, and Poisson's ratio.

### Claim 8 (depends on 1)

The method of claim 1, wherein the salt creep analysis is based on secondary salt creep; a combination of secondary salt creep and tertiary salt creep; or a combination of primary salt creep, secondary salt creep, and tertiary salt creep.

### Claim 9 (depends on 1)

The method of claim 1, wherein rheology parameters of the proposed cement slurry are used in step (c) to determine experimentally the rheology of the proposed cement slurry versus salt dissolution curve, and
wherein the rheology parameters are selected from the group consisting of plastic viscosity, Bingham model yield point, Herschel-Bulkley model parameters, and any combination thereof.

### Claim 10 (depends on 1)

The method of claim 1, further comprising a wellhead with a tubular extending therefrom and into the wellbore, and a pump fluidly coupled to the tubular; and wherein
step (n) is performed by introducing the final cement slurry into the wellbore through the tubular.

### Claim 11

A method comprising:
(a) calculating a theoretical first wellbore radius in a subterranean salt formation having a treatment fluid therein based on salt creep analysis in the presence of formation-treatment fluid;
(b) calculating a theoretical second wellbore radius in the subterranean salt formation during a cementing operation with a proposed cement slurry based on salt creep analysis in the presence of formation-cement slurry,
wherein the cementing operation involves forming a proposed cement sheath within the wellbore, and wherein the proposed cement sheath must withstand a wellbore load to prevent failure of the cement sheath in the wellbore;
(c) determining experimentally a rheology of the proposed cement slurry versus salt dissolution curve;
(d) calculating a maximum salt dissolution value based on thermodynamic salt dissolution;
(e) calculating a theoretical final wellbore radius in the subterranean salt formation based on the theoretical first wellbore radius, the theoretical second wellbore radius, and salt dissolution after forming the proposed cement sheath;
(f) calculating theoretically whether the proposed cement sheath is capable of withstanding the wellbore load by calculating theoretical thermal and thermo-mechanical properties of the proposed cement slurry based on salt creep analysis in the presence of formation-cement sheath;
(g) determining experimentally whether the proposed cement sheath is capable of withstanding the wellbore load based on an ultrasonic cement analyzer test and actual thermal and thermo-mechanical properties of the proposed cement slurry after salt dissolution;
(h) calculating theoretically a theoretical pump time and a theoretical pump pressure for the treatment fluid and the proposed cement slurry based on a computational fluid dynamics model,
wherein the theoretical pump pressure for the treatment fluid and the proposed cement slurry is between a pore pressure and a fracture gradient of the subterranean salt formation, and
wherein the theoretical pump time for the treatment fluid and the proposed cement slurry is such that the proposed cement slurry will theoretically permit formation of the proposed cement sheath in the wellbore without substantial premature curing;
(i) determining experimentally whether the theoretical pumping time for the treatment fluid and the proposed cement slurry will permit formation of the proposed cement sheath in the wellbore without substantial premature curing based on a thickening time test of the proposed cement slurry;
(j) performing steps (f)-(g) before steps (h)-(i), or
performing steps (h)-(i) before steps (f)-(g);
(k) establishing a final cement slurry, a final pumping pressure and time for the treatment fluid, and a final pumping pressure and time for the cement slurry;
(l) performing a wellbore operation with the treatment fluid using the final pumping time and pressure for the treatment fluid; and
(m) performing the cementing operation with the final cement slurry using the final pumping time and pressure for the final cement slurry.

### Claim 12 (depends on 11)

The method of claim 11, wherein step (j) comprises performing (f)-(g) before steps (h)-(i), and
further comprising manipulating the proposed cement slurry after at least one of:
step (f), and repeating steps (b)-(f) until the proposed cement sheath based on the proposed cement slurry that has been manipulated is theoretically capable of withstanding the wellbore load,
step (g), and repeating steps (b)-(g) until the proposed cement sheath based on the proposed cement slurry that has been manipulated is experimentally capable of withstanding the wellbore load,
step (h), and repeating steps (b)-(h) until the theoretical pumping pressure for the treatment fluid and the proposed cement slurry that has been manipulated is theoretically between the pore pressure and the fracture gradient of the subterranean salt formation and the theoretical pumping time for the treatment fluid and the proposed cement slurry that has been manipulated theoretically permits formation of the proposed cement sheath with the proposed cement slurry that has been manipulated in the wellbore without substantial premature curing, and
step (i), and repeating steps (b)-(i) until the theoretical pumping time experimentally permits formation of the proposed cement sheath in the wellbore with the proposed cement slurry that has been manipulated without substantial premature curing.

### Claim 13 (depends on 11)

The method of claim 11, wherein step (j) comprises performing steps: (h)-(i) before steps: (f)-(g), and
further comprising manipulating the proposed cement slurry after at least one of:
step (h), and repeating steps (b)-(e) and (h) until the theoretical pumping pressure for the treatment fluid and the proposed cement slurry that has been manipulated is theoretically between the pore pressure and the fracture gradient of the subterranean salt formation and the theoretical pumping time for the treatment fluid and the proposed cement slurry that has been manipulated theoretically permits formation of the proposed cement sheath with the proposed cement slurry that has been manipulated in the wellbore without substantial premature curing,
step (i), and repeating steps (b)-(e) and (h)-(i) until the theoretical pumping time experimentally permits formation of the proposed cement sheath in the wellbore with the proposed cement slurry that has been manipulated without substantial premature curing,
step (f), and repeating steps (b)-(e), (h)-(i), and (f) until the proposed cement sheath based on the proposed cement slurry that has been manipulated is theoretically capable of withstanding the wellbore load, and
step (g), and repeating steps (b)-(e), (h)-(i), and (f)-(g) until the proposed cement sheath based on the proposed cement slurry that has been manipulated is experimentally capable of withstanding the wellbore load.

### Claim 14 (depends on 11)

The method of claim 11, wherein the computational fluid dynamics model of step (h) is used to determine the theoretical pump time and pressure of the treatment fluid and the proposed cement slurry based on: a flow rate of the treatment fluid, a flow rate of the proposed cement slurry, a rheology of the treatment fluid, a rheology of the proposed cement slurry, a standoff profile, and the theoretical final wellbore radius.

### Claim 15 (depends on 14)

The method of claim 14, wherein at least one of the flow rate of the treatment fluid and the flow rate of the cement slurry are manipulated and step (h) is repeated.

### Claim 16 (depends on 14)

The method of claim 14, wherein the rheology parameters of the treatment fluid and the rheology parameters of the proposed cement slurry are selected from the group consisting of plastic viscosity, Bingham model yield point, Herschel-Bulkley model parameters, and any combination thereof.

### Claim 17 (depends on 11)

The method of claim 11, wherein the theoretical thermal and thermo-mechanical properties of the proposed cement are calculated based on at least one of thermal conductivity, thermal diffusivity, tensile strength, compressive strength, hydration volume change, Young's modulus, and Poisson's ratio.

### Claim 18 (depends on 11)

The method of claim 11, wherein the salt creep analysis is based on secondary salt creep; a combination of secondary salt creep and tertiary salt creep; or a combination of primary salt creep, secondary salt creep, and tertiary salt creep.

### Claim 19 (depends on 11)

The method of claim 11, wherein rheology parameters of the proposed cement slurry are used in step (c) to determine experimentally the rheology of the proposed cement slurry versus salt dissolution curve, and
wherein the rheology parameters are selected from the group consisting of plastic viscosity, Bingham model yield point, Herschel-Bulkley model parameters, and any combination thereof.

### Claim 20 (depends on 11)

The method of claim 11, further comprising a wellhead with a tubular extending therefrom and into the wellbore, and a pump fluidly coupled to the tubular; and wherein
step (m) is performed by introducing the final cement slurry into the wellbore through the tubular.