Acid Stimulation Modeling for Radial Flow Injection Rates
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Solution Overview
Problem
Existing acid stimulation models for hydrocarbon wells lack accuracy in predicting optimal injection rates due to unaccounted radial dispersion, leading to potentially inaccurate design and increased costs from pressure build-up testing.
Innovation Solution
Developing radial breakthrough curves that account for radial flow and wormhole lengths, using core flow tests and virtual simulations to calculate skin, acid concentration, and fluid velocity, allowing for more precise acid stimulation treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear pore volume to breakthrough curves are used for acid stimulation design, then the modeling is cost-effective, but the accuracy of optimal injection rate prediction deteriorates due to unaccounted radial dispersion
Solution Approach 1:
The patent transforms the linear flow model parameters into radial flow model parameters by applying geometric scaling factors. The linear PVBT curves are converted to radial PVBT curves using the relationship between linear and radial flow geometry, allowing the use of simple linear test data to predict radial stimulation outcomes accurately without requiring complex radial simulations
Solution Approach 2:
The patent creates a scaled copy of the linear flow model to represent radial flow conditions. By using the linear core flood test results and applying geometric scaling relationships, the model reproduces radial stimulation behavior from simpler linear test data, achieving both cost-effectiveness and accuracy
2Reliability
If pressure build-up testing is performed to ascertain wormhole formation effectiveness, then well-specific information is obtained, but the cost and time consumption increase significantly
Solution Approach 1:
The patent performs acid stimulation modeling and prediction before actual field testing. By using the radial PVBT model to predict wormhole formation and stimulation effectiveness in advance, operators can optimize treatment design without requiring expensive post-treatment pressure build-up tests to verify performance
Solution Approach 2:
The patent replaces the mechanical pressure build-up testing system with a computational modeling system. Instead of performing physical pressure measurements after stimulation to assess wormhole formation, the model uses chemical reaction kinetics and fluid flow equations to predict stimulation outcomes, eliminating the need for costly field testing
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
Enhances the accuracy of acid stimulation design by optimizing injection rates, ensuring complete formation stimulation and maximizing hydrocarbon recovery while reducing the need for costly pressure build-up testing.
Implementation Method 1
the injected fluid may extend the effective wellbore drainage radius by dissolving formation rock to form channels such as wormholes
Implementation Method 2
the acid behavior upon injection during stimulation is a radial dispersion that is largely unaccounted for by the known modeling techniques
Data Source
AI summary
Stimulation treatments are designed and performed in a manner that takes into account radial acid flow into the formation. A reservoir core plug is selected and a linear core flow test is performed. The core flow test comprises measuring a flowing fraction, injecting into the core plug a treatment volume of at least one candidate stimulation fluid at an injection rate at reservoir conditions, and measuring an effective reaction rate constant. The linear flow data are then scaled to radial flow. A skin, an acid concentration at a wormhole tip and a fluid velocity at a wormhole tip are calculated. A stimulation treatment is then performed. The method can also be performed on analog cores. The stimulation treatment may be matrix acidizing, fracture acidizing or acidizing natural fractures.