System and method to test wells at continuously-varying production rates

Abstract

A method includes: accessing databases storing pressure data of a reservoir at a downhole location, temporal production data of the reservoir, petrophysical parameters, and fluid properties; creating grids comprising sections during which respective segments of temporal production data are measured, wherein each of the respective segments of temporal production data is continuous within a corresponding section of the grids, and wherein the temporal production data comprise at least one discontinuity between two neighboring sections of the grid; based on the temporal production data, petrophysical parameters, and fluid properties, computing a superposition-time function over the sections, wherein the superposition-time function is free from the at least one discontinuity; constructing a plot of the pressure data versus the computed superposition-time function; and based on the plot of the pressure data, deriving characteristics of the reservoir such that the reservoir is monitored despite the at least one discontinuity in the temporal production data.

What is claimed is: 
     
         1 . A computer-implemented method comprising:
 accessing one or more databases storing geo-exploration data associated with a reservoir, the geo-exploration data comprising: pressure data measured temporally at a downhole location inside a well of the reservoir, temporal production data of the reservoir through the well and measured at a surface of the well, petrophysical parameters of the reservoir, and fluid properties of the reservoir;   creating temporal grids comprising sections during which respective segments of temporal production data are measured, wherein each of the respective segments of temporal production data is continuous within a corresponding section of the grids, and wherein the temporal production data comprise at least one discontinuity between two neighboring sections of the grid;   based on, at least in part, the temporal production data, the petrophysical parameters of the reservoir, and the fluid properties of the reservoir, computing a superposition-time function over the sections, wherein the superposition-time function is free from the at least one discontinuity;   constructing a plot of the pressure data versus the computed superposition-time function; and   based on, at least in part, the plot of the pressure data, deriving characteristics of the reservoir such that the reservoir is monitored continuously despite the at least one discontinuity in the temporal production data.   
     
     
         2 . The computer-implemented method of  claim 1 , wherein the characteristics of the reservoir comprise: a transmissibility, a reservoir flow capacity, and a reservoir permeability. 
     
     
         3 . The computer-implemented method of  claim 2 , further comprising:
 determining a slope of the pressure data being plotted versus the superposition-time function, wherein the slope encodes at least one of the characteristics of the reservoir.   
     
     
         4 . The computer-implemented method of  claim 3 , further comprising:
 based on, at least in part, the determined slope, iteratively determining at least one of the characteristics of the reservoir.   
     
     
         5 . The computer-implemented method of  claim 2 , further comprising:
 computing a pressure derivative with respect to the computed superposition-time function, a log-log plot of pressure derivative, and an intercept of the pressure derivative plot, wherein the intercept encodes at least one of the characteristics of the reservoir.   
     
     
         6 . The computer-implemented method of  claim 1 , further comprising:
 based on, at least in part, the derived characteristics of the reservoir, predicting a production rate of the reservoir beyond the temporal production data.   
     
     
         7 . The computer-implemented method of  claim 1 , wherein the temporal production data comprise: a production rate, and an injection rate. 
     
     
         8 . A computer system comprising one or more hardware processors configured to perform operations of:
 accessing one or more databases storing geo-exploration data associated with a reservoir, the geo-exploration data comprising: pressure data measured temporally at a downhole location inside a well of the reservoir, temporal production data of the reservoir through the well and measured at a surface of the well, petrophysical parameters of the reservoir, and fluid properties of the reservoir;   creating temporal grids comprising sections during which respective segments of temporal production data are measured, wherein each of the respective segments of temporal production data is continuous within a corresponding section of the grids, and wherein the temporal production data comprise at least one discontinuity between two neighboring sections of the grid;   based on, at least in part, the temporal production data, the petrophysical parameters of the reservoir, and the fluid properties of the reservoir, computing a superposition-time function over the sections, wherein the superposition-time function is free from the at least one discontinuity;   constructing a plot of the pressure data versus the computed superposition-time function; and   
       based on, at least in part, the plot of the pressure data, deriving characteristics of the reservoir such that the reservoir is monitored continuously despite the at least one discontinuity in the temporal production data. 
     
     
         9 . The computer system of  claim 8 , wherein the characteristics of the reservoir comprise: a transmissibility, a reservoir flow capacity, and a reservoir permeability. 
     
     
         10 . The computer system of  claim 9 , wherein the operations further comprise:
 determining a slope of the pressure data being plotted versus the superposition-time function, wherein the slope encodes at least one of the characteristics of the reservoir.   
     
     
         11 . The computer system of  claim 10 , wherein the operations further comprise:
 based on, at least in part, the determined slope, iteratively determining at least one of the characteristics of the reservoir.   
     
     
         12 . The computer system of  claim 9 , wherein the operations further comprise:
 computing a pressure derivative with respect to the computed superposition-time function, a log-log plot of pressure derivative, and an intercept of the pressure derivative plot, wherein the intercept encodes at least one of the characteristics of the reservoir.   
     
     
         13 . The computer system of  claim 8 , wherein the operations further comprise:
 based on, at least in part, the derived characteristics of the reservoir, predicting a production rate of the reservoir beyond the temporal production data.   
     
     
         14 . The computer system of  claim 8 , wherein the temporal production data comprise: a production rate, and an injection rate. 
     
     
         15 . A non-transitory computer-readable medium comprising software instructions which, when executed by a computer processor, causes the computer processor to perform operations of:
 accessing one or more databases storing geo-exploration data associated with a reservoir, the geo-exploration data comprising: pressure data measured temporally at a downhole location inside a well of the reservoir, temporal production data of the reservoir through the well and measured at a surface of the well, petrophysical parameters of the reservoir, and fluid properties of the reservoir;   creating temporal grids comprising sections during which respective segments of temporal production data are measured, wherein each of the respective segments of temporal production data is continuous within a corresponding section of the grids, and wherein the temporal production data comprise at least one discontinuity between two neighboring sections of the grid;   based on, at least in part, the temporal production data, the petrophysical parameters of the reservoir, and the fluid properties of the reservoir, computing a superposition-time function over the sections, wherein the superposition-time function is free from the at least one discontinuity;   constructing a plot of the pressure data versus the computed superposition-time function; and   based on, at least in part, the plot of the pressure data, deriving characteristics of the reservoir such that the reservoir is monitored continuously despite the at least one discontinuity in the temporal production data.   
     
     
         16 . The non-transitory computer-readable medium of  claim 15 , wherein the characteristics of the reservoir comprise: a transmissibility, a reservoir flow capacity, and a reservoir permeability. 
     
     
         17 . The non-transitory computer-readable medium of  claim 16 , wherein the operations further comprise:
 determining a slope of the pressure data being plotted versus the superposition-time function, wherein the slope encodes at least one of the characteristics of the reservoir.   
     
     
         18 . The non-transitory computer-readable medium of  claim 17 , wherein the operations further comprise:
 based on, at least in part, the determined slope, iteratively determining at least one of the characteristics of the reservoir.   
     
     
         19 . The non-transitory computer-readable medium of  claim 17 , wherein the operations further comprise:
 computing a pressure derivative with respect to the computed superposition-time function, a log-log plot of pressure derivative, and an intercept of the pressure derivative plot, wherein the intercept encodes at least one of the characteristics of the reservoir.   
     
     
         20 . The non-transitory computer-readable medium of  claim 15 , wherein the operations further comprise:
 based on, at least in part, the derived characteristics of the reservoir, predicting a production rate of the reservoir beyond the temporal production data, wherein the temporal production data comprise: a production rate, and an injection rate.