Dynamic Acidizing Injection Rate Control for Wormhole Penetration
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Solution Overview
Problem
Traditional acidizing methods in subterranean formations often fail to create deep-penetrating wormholes due to inappropriate injection rates, leading to inefficient hydrocarbon production and damage in carbonate formations.
Innovation Solution
The method involves determining the wellbore pressure and fluid flow distribution to create a pore volume to breakthrough (PVBT) curve, allowing for real-time adjustments in acidizing fluid injection rates to achieve optimal interstitial velocities, thereby identifying and controlling wormholing regimes, such as compact, uniform, or dominant dissolution, using numerical models and diverting agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the injection rate is increased to create wormholes, then the acid can penetrate deeper into the formation, but the wormholes become thick and shallow rather than deep-penetrating
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant injection rate to a dynamic declining injection rate profile. The injection rate is reduced over time during the acidizing treatment, allowing the system to adapt as wormholes develop. This dynamic adjustment enables the acid to penetrate deeper while maintaining efficient wormhole formation, resolving the contradiction between penetration depth and treatment efficiency.
Solution Approach 2:
The patent changes the injection rate parameter from a constant high value to a declining profile over time. This parameter change allows the system to optimize wormhole development at different stages: higher initial rates create wormholes, while declining rates enable deeper penetration. This resolves the contradiction by adjusting the injection rate parameter dynamically throughout the treatment process.
2Length of moving object
If the injection rate is decreased to achieve deep penetration, then wormholes can penetrate deeper into the formation, but large volumes of acid are required and pump capacity is limited
Solution Approach 1:
The declining injection rate profile dynamically adjusts the acid volume delivery over time. By starting with higher rates and gradually declining, the system maximizes penetration depth while optimizing acid volume utilization. This dynamic approach prevents both the waste of acid volume associated with constant high rates and the penetration limitations of constant low rates.
Solution Approach 2:
The patent applies preliminary action by establishing wormholes early in the treatment with higher injection rates before transitioning to lower rates for deep penetration. This preliminary wormhole creation provides conduits that guide subsequent acid flow, ensuring that the acid volume is efficiently utilized for deep penetration rather than being wasted on creating new pathways.
3Ease of operation
If traditional MAPDIR injection is used, then the process is simple to operate, but it uses large volumes of acid and may not produce the desired dominant wormhole regime
Solution Approach 1:
The patent implements feedback by using real-time monitoring of injection parameters and wormhole development to adjust the injection rate profile. The declining rate is determined based on formation response and wormhole propagation characteristics, allowing precise control of the dominant wormhole regime while maintaining operational simplicity through automated control systems.
Solution Approach 2:
The system transitions from static constant-rate operation to dynamic declining-rate operation, enabling precise control of wormhole regime development. The dynamic adjustment of injection rate provides the precision needed to achieve dominant wormhole formation while maintaining ease of operation through systematic rate decline profiles.
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 approach enhances acidizing treatments by increasing stimulation efficiency, reducing damage, and ensuring effective wormhole formation, leading to improved hydrocarbon production and reduced hands-on time for engineers.
Implementation Method 1
The acid of the aqueous acid treatment reacts with acid soluble materials contained in the formation to increase the size of the pore spaces and increase the permeability of the formation
Implementation Method 2
involves the introduction of an acid into a subterranean formation under pressure so that the acid flows through the pore spaces of the formation
Data Source
AI summary
Methods and systems for designing, monitoring, and/or performing acidizing treatments in subterranean formations are provided. A method comprises: determining a wellbore pressure and a fluid flow distribution for an acidizing fluid introduced into an interval of a well bore penetrating a portion of a subterranean formation; determining an optimum interstitial velocity for the acidizing fluid in the subterranean formation and an interstitial velocity of the acidizing fluid at a tip of a wormhole in the subterranean formation at a first flow rate at each of a plurality of depths; and if the interstitial velocity of the acidizing fluid at the tip of the wormhole is less than the optimum interstitial velocity at one or more of the plurality of depths, identifying a second flow rate for introducing the acidizing fluid into the interval of the well bore that is greater than the first flow rate.