Check Valve Well Completion for Targeted Acid Stimulation
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Solution Overview
Problem
Stimulating long horizontal wells is challenging due to the difficulty in achieving targeted acid placement and radial impingement, leading to uneven wormhole growth and reduced production efficiency, especially in ultra-long open hole completions where acid injection methods are limited by ICDs and coiled tubing constraints.
Innovation Solution
A method using a production liner with check valves and ball sealers to sequentially stimulate different sections of the well by controlling pressure differentials, allowing stimulation fluid to flow through check valves and blocking flow with ball sealers to isolate treated intervals, enabling efficient acid placement and stimulation across multiple zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acid is injected through ICDs to stimulate the formation, then acid can be delivered to the well, but the ICDs restrict the injection rate and fail to achieve radial impingement on the formation
Solution Approach 1:
The production liner is divided into multiple discrete intervals with individual port assemblies at different locations. Each port assembly can be independently activated or blocked, allowing segmented acid injection into different formation zones. This segmentation enables high-rate injection into specific intervals without being restricted by ICD flow control mechanisms.
Solution Approach 2:
The invention removes the ICD flow restriction mechanism from the acid injection system. By using dedicated port assemblies in the production liner that bypass the ICDs, the system extracts the harmful flow restriction element and replaces it with unrestricted injection capability, achieving the necessary high injection rates for radial impingement.
2Productivity
If acid flows into areas of high permeability, then acid injection is easier, but the low permeability zones remain unstimulated
Solution Approach 1:
Different intervals of the production liner are equipped with port assemblies having different opening pressures tailored to local formation characteristics. Low permeability zones are assigned ports with lower opening pressures to facilitate acid entry, while high permeability zones have ports with higher opening pressures. This local customization ensures targeted stimulation accuracy across varying formation qualities.
Solution Approach 2:
The port assemblies are pre-configured with specific opening pressures during installation based on formation evaluation data. This preliminary action of setting appropriate pressure thresholds ensures that acid will naturally preferentially enter low permeability zones first, achieving targeted stimulation before moving to high permeability areas as pressure builds.
3Manufacturing precision
If check valves are used to control acid flow into intervals, then targeted stimulation is achieved, but ball sealers are needed to block flow between intervals
Solution Approach 1:
The check valves are designed to automatically open and close based on pressure differential across the port assembly. When acid injection pressure exceeds the predetermined opening pressure, the check valve opens to allow acid flow. When injection stops or pressure drops, the check valve automatically closes to prevent backflow. This self-service mechanism eliminates the need for ball sealers or other active closing mechanisms, simplifying the system while maintaining precise interval isolation.
4Ease of operation
If coiled tubing is used for acid injection, then acid can be delivered to horizontal wells, but the tubing constraints limit injection capability in ultra-long completions
Solution Approach 1:
The invention extracts the acid injection function from the coiled tubing system and relocates it to the production liner port assemblies. By removing the coiled tubing constraint from the injection path and using the production liner's inherent structure with dedicated ports, the system achieves high-rate injection capability without the flexibility and length limitations of coiled tubing in ultra-horizontal completions.
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 allows for high-rate, efficient acid stimulation of ultra-long horizontal open hole wells, improving hydrocarbon recovery by ensuring targeted stimulation and preventing overstimulation, thus optimizing production from varying rock types and permeabilities.
Implementation Method 1
the stimulation fluid is at a pressure sufficient to open a plurality of check valves in the first interval, allowing stimulation fluid to flow into the first interval
Implementation Method 2
the ball sealers are configured to block flow through the plurality of check valves in the first interval
Data Source
AI summary
Methods and systems for completing a well including injecting a stimulation fluid to stimulate a first interval in the reservoir. The stimulation fluid is at a pressure sufficient to open a number of check valves in the first interval, allowing stimulation fluid to flow into the first interval. A number of ball sealers configured to block flow through the check valves are dropped into the well to stop the flow of the stimulation fluid into the first interval and begin treatment of a second interval. The stimulation fluid is injected to stimulate a subsequent interval with pressure sufficient to open a number of check valves in the subsequent interval, allowing stimulation fluid to flow into the subsequent interval. The dropping of ball sealers is repeated until all intervals are treated.