Injectivity Loss Estimation in Carbonate Reservoirs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for predicting loss of injectivity in carbonate reservoirs due to reactive effects and suspended solids are inadequate, as they do not consider the interaction between injected fluids and the reservoir, leading to pessimistic and inconsistent results, especially when using unbalanced fluids and CO2, which affect permeability and formation of preferential paths.
Innovation Solution
A combined experimental and simulation method that accounts for both rock-fluid interaction and the presence of suspended solids, allowing for a more realistic prediction of injectivity loss by determining key parameters through reactive fluid injection tests and adjusting the area open to flow, considering the effects of dissolution and solid presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional flow tests in porous media are used to predict injectivity loss, then the methodology is simple and established, but the results are pessimistic and inconsistent with field observations because reactive effects are not considered
Solution Approach 1:
The patent combines reactive flow tests with conventional flow tests, integrating chemical reaction effects into the injectivity prediction methodology. This merging allows the system to capture both dissolution effects (which improve injectivity) and solids deposition effects (which reduce injectivity), resolving the contradiction between measurement precision and methodology complexity
Solution Approach 2:
The patent introduces new parameters to characterize reactive effects, including dissolution rate constants, mineralogical composition, fluid chemistry parameters, and reactive permeability. These parameter changes enable more accurate prediction of injectivity loss by accounting for chemical interactions between injected fluids and carbonate reservoir rock
2Measurement precision
If reactive flow tests are used to account for dissolution reactions, then the prediction becomes more realistic, but it is not possible to add suspended solids to the injected fluid due to bottle agitation issues and piston damage
Solution Approach 1:
The patent uses an intermediary approach by conducting separate reactive flow tests and separate flow tests with solids, then combining the results through a unified mathematical model. This intermediary method allows suspended solids to be added in the flow test portion while reactive effects are captured in the reactive flow test portion, resolving the operational feasibility issue
Solution Approach 2:
The patent segments the injectivity prediction into two components: one accounting for reactive dissolution effects and another accounting for solids deposition effects. This segmentation allows each component to be tested under appropriate conditions (reactive tests without solids, flow tests with solids) and then integrated, resolving the contradiction between measurement precision and ease of operation
3Measurement precision
If the presence of suspended solids is considered, then pore plugging and injectivity loss are better predicted, but the interaction with reactive dissolution effects is not accounted for
Solution Approach 1:
The patent creates a composite prediction model that combines the effects of suspended solids deposition and reactive dissolution. This composite approach uses a unified mathematical framework that integrates both harmful effects (solids plugging) and beneficial effects (dissolution enhancing permeability), resolving the contradiction between measurement precision and methodology applicability to carbonate reservoirs
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides a more accurate prediction of injectivity loss, enabling better scheduling of interventions and reducing production losses by accounting for both positive and negative contributions to injectivity, thus optimizing well performance in carbonate reservoirs.
Implementation Method 1
The injection of unbalanced fluids and the presence of CO2 lead to carbonate dissolution reactions according to the equations below: CaCO3+H+⇔Ca+2+HCO3−; 2CaCO3+Mg+2⇔Ca+2+CaMg(CO3)2
Implementation Method 2
In this region, part of the CO2 present in the oil and/or injected passes into the injection water, making it more reactive
Data Source
AI summary
The present invention addresses to a combined experimental and simulation method for estimating the loss of injectivity in carbonate reservoirs subjected to water injection considering both the effects of reactivity and the presence of suspended solids and/or oil, aiming at greater efficiency of water injection. By means of the present invention, it is possible to understand the combined results of rock-fluid interaction and presence of solids in injection fluids and to determine parameters for injectivity loss models, enabling a more realistic prediction for scenarios of carbonate reservoirs.