Method for designing spacer trains for reverse circulation cementing

Abstract

A method may include: receiving wellbore data comprising wellbore geometry, density and rheology of a drilling fluid, and density and rheology of a cement slurry, and receiving a design objective function; generating a plurality of spacer fluid train designs where each of the plurality of spacer fluid train designs comprise two or more spacer fluids where each spacer fluid has a specified density, yield point, plastic viscosity, and volume; calculating a solution to an objective function and annular displacement for each of the plurality of spacer fluid train designs in a reverse cementing operation using a displacement simulator having inputs comprising the wellbore data and the plurality of spacer fluid train designs; comparing each solution to the objective function to the design objective function; selecting a spacer fluid train design from the plurality of spacer fluid train designs which meets the design objective function; and preparing a spacer fluid train based on the selected spacer fluid train design.

What is claimed is: 
     
         1 . A method comprising:
 receiving wellbore data comprising (i) wellbore geometry, density and rheology of a drilling fluid, and (ii) density and rheology of a cement slurry, and receiving a design objective function;   generating a plurality of spacer fluid train designs where each of the plurality of spacer fluid train designs comprises two or more spacer fluids where each spacer fluid has a specified density, yield point, plastic viscosity, and volume;   calculating a solution to an objective function and annular displacement for each of the plurality of spacer fluid train designs in a reverse cementing operation using a displacement simulator having inputs comprising the wellbore data and the plurality of spacer fluid train designs;   comparing each solution to the objective function to the design objective function;   selecting a spacer fluid train design from the plurality of spacer fluid train designs which meets the design objective function; and   preparing a spacer fluid train based on the selected spacer fluid train design.   
     
     
         2 . The method of  claim 1  wherein the design objective function comprises at least one objective selected from the group consisting of maximum tail cement displacement efficiency, minimum height of cement column in casing, maximum first occurrence time of cement at casing shoe, and combinations thereof. 
     
     
         3 . The method of  claim 1  further comprising receiving user input data comprising at least one of spacer density increment, spacer volume increment, or target displacement efficiency at a casing shoe. 
     
     
         4 . The method of  claim 3  wherein generating the plurality of spacer fluid train designs comprises generating spacer fluid designs using the user input data. 
     
     
         5 . The method of  claim 1  wherein the solution to the objective function comprises at least one objective selected from the group consisting of maximum tail cement displacement efficiency, minimum height of cement column, maximum first occurrence time of cement at casing shoe, and combinations thereof. 
     
     
         6 . The method of  claim 1  further comprising generating at least one additional plurality of spacer fluid train designs in response to the solution to the objective function and/or annular displacement for each of the plurality of spacer fluid train designs. 
     
     
         7 . The method of  claim 6  wherein the additional pluralities of spacer fluid drain designs includes changes in at least one of number of spacer fluids in the spacer fluid train design and/or changes in a density, plastic viscosity, or volume of at least one spacer fluid in the spacer fluid train. 
     
     
         8 . The method of  claim 6  wherein the spacer fluid train designs comprise between 2 and 20 spacer fluids. 
     
     
         9 . The method of  claim 6  further comprising analyzing the annular displacement for each of the plurality of spacer fluid train designs using gradient descent to generate a gradient descent response, wherein generating additional pluralities of spacer fluid train designs comprises selecting at least one of spacer fluid has a specified density, plastic viscosity, or volume in response to the gradient descent response. 
     
     
         10 . The method of  claim 6  further comprising receiving user input data comprising at least one of a spacer fluid volume, a spacer fluid density, or a spacer fluid rheology and wherein generating additional pluralities of spacer fluid train designs comprises selecting at least one of spacer fluid based on the user input data. 
     
     
         11 . The method of  claim 6  further comprising calculating a solution to an objective function and annular displacement for each of the additional plurality of spacer fluid train designs in a reverse cementing operation using a displacement simulator having inputs comprising the wellbore data and the additional plurality of spacer fluid train designs;
 comparing each solution to the objective function to the design objective function; and 
 selecting a spacer fluid train design from the additional plurality of spacer fluid train designs which meets the design objective function. 
 
     
     
         12 . The method of  claim 6  further analyzing the annular displacement using response surface modeling and determining significant factors, wherein generating additional pluralities of spacer fluid train designs comprises selecting at least one of spacer fluid has a specified density, plastic viscosity, or volume in response to the significant factors. 
     
     
         13 . The method of  claim 1  further comprising introducing the spacer fluid train into a wellbore in a reverse cementing operation. 
     
     
         14 . The method of  claim 13  further comprising displacing a drilling fluid in the wellbore using the spacer fluid train. 
     
     
         15 . The method of  claim 13  further comprising displacing the spacer fluid train with a cement slurry. 
     
     
         16 . The method of  claim 13  wherein the spacer fluid train comprises two or more spacer fluids, where each spacer has a different density between a density of the drilling fluid and the cement slurry. 
     
     
         17 . A method comprising:
 a. receiving wellbore data comprising (i) wellbore geometry, (ii) density and rheology of a drilling fluid, and (iii) density and rheology of a cement slurry, and receiving a design objective function;   b. generating a plurality of spacer fluid train designs where each of the plurality of spacer fluid train designs comprise two or more spacer fluids where each spacer fluid has a specified density, yield point, plastic viscosity, and volume;   c. calculating a solution to an objective function and annular displacement for each of the plurality of spacer fluid train designs in a reverse cementing operation using a displacement simulator having inputs comprising the wellbore data and the plurality of spacer fluid train designs;   d. comparing each solution to the objective function to the design objective function and selecting a spacer fluid train design from the plurality of spacer fluid train designs if the solution to the objective function meets the design objective function or repeating b-d if the solution to the objective function does not meet the design objective function; and   e. preparing a spacer fluid train based on the selected spacer fluid train design.   
     
     
         18 . The method of  claim 17  wherein the design objective function comprises at least one objective selected from the group consisting of maximum tail cement displacement efficiency, minimum height of cement column, maximum first occurrence time of cement at casing shoe, and combinations thereof. 
     
     
         19 . The method of  claim 17  further comprising analyzing the annular displacement for each of the plurality of spacer fluid train designs using gradient descent to generate a gradient descent response, wherein generating additional pluralities of spacer fluid train designs comprises selecting at least one of spacer fluid has a specified density, plastic viscosity, or volume in response to the gradient descent response. 
     
     
         20 . The method of  claim 17  further analyzing the annular displacement using response surface modeling and determining significant factors, wherein generating additional pluralities of spacer fluid train designs comprises selecting at least one of spacer fluid has a specified density, plastic viscosity, or volume in response to the significant factors.