Methods and systems for estimating sizes and effects of wellbore obstructions in water injection wells

A system to estimate one or more physical dimensions of one or more actual obstructions in a wellbore of an injection well, the system comprising:

• one or more processors;
• one or more input and output units in communication with the one or more processors and positioned to receive a user selection of a wellbore of an injection well;
• non-transitory computer-readable medium positioned in communication with the one or more processors and having computer program stored thereon including a set of instructions that when executed by one or more processors cause the one or more processors to perform operations of:
• (a) estimating one or more locations within the wellbore and one or more physical dimensions of one or more actual obstructions to thereby define an obstruction;
• (b) obtaining two or more sets of actual measurements of two or more characteristics of fluid flow in the wellbore including two or more actual injection rates and two or more actual injection pressures;
• (c) calculating a plurality of upstream pressure values of the obstruction;
• (d) calculating a plurality of corresponding downstream pressure values across the obstruction responsive to a first estimated injectivity index value;
• (e) determining a plurality of pressure differentials between the upstream pressure values and the corresponding downstream pressure values with a first set of actual fluid injection rates responsive to one or more estimated downhole choke behaviors for the wellbore to thereby model fluid flow across the obstruction to thereby define a simulated obstruction model;
• (f) determining a first outflow performance relationship for the fluid flow through the wellbore responsive to the simulated obstruction model to thereby model well performance with the obstruction;
• (g) determining a second estimated injectivity index value responsive to matching a first set of actual measurements of two or more characteristics of fluid flow in the wellbore with a set of simulated fluid flow values obtained from the model well performance with the obstruction;
• (h) performing iteratively steps (b) to (g) until the first estimated injectivity index value and the second estimated injectivity index value converge within preselected tolerance limits;
• (i) determining one or more physical dimensions of the obstruction in the wellbore responsive to the simulated obstruction model and a plurality of measurements of one or more characteristics associated with the wellbore responsive to the first estimated injectivity index value and the second estimated injectivity index value converge within preselected tolerance limits;
• and
• (j) determining one or more changes to well conditions responsive to determining the one or more physical dimensions of the obstruction in the wellbore.

A computer-implemented method to determine dimensions of one or more actual obstructions identified as being in a wellbore of an injection well, the method comprising:

• (a) obtaining a plurality of measurements of one or more characteristics of fluid flow in a wellbore of an injection well, a plurality of measurements of one or more characteristics of a reservoir associated with the injection well, and a plurality of measurements of one or more characteristics associated with the wellbore of the injection well;
• (b) creating one or more correlations based on a first estimated injectivity index to simulate fluid flow across one or more simulated mechanical obstructions to thereby define a simulated obstruction performance model, the one or more correlations being responsive to the plurality of measurements of one or more characteristics of fluid flow in the wellbore of the injection well, the plurality of measurements of one or more characteristics of the reservoir associated with the injection well, the plurality of measurements of one or more characteristics associated with the wellbore of the injection well, and a plurality of simulated fluid flow measurements across the at least one simulated mechanical obstruction in the wellbore;
• (c) determining a second estimated injectivity index, responsive to the simulated obstruction performance model, the plurality of measurements of one or more characteristics of actual fluid flow in the wellbore of the injection well, the plurality of measurements of one or more characteristics of the reservoir associated with the injection well, and the plurality of measurements of one or more characteristics associated with the wellbore of the injection well;
• (d) performing iteratively steps (a) to (c) until the first estimated injectivity index value and the second estimated injectivity index value converge within preselected tolerance limits;
• (e) determining dimensions of the one or more actual obstruction in the wellbore responsive to the simulated obstruction performance model and the plurality of measurements of one or more characteristics associated with the wellbore of the injection well when the first estimated injectivity index and the second estimated injectivity index converge within acceptable tolerance limits;
• and
• (f) determining one or more changes to well conditions responsive to determining one or more physical dimensions of the one or more actual obstructions in the wellbore.