Hydraulic Fracturing Near Wellbore Proppant Placement
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Solution Overview
Problem
Current hydraulic fracturing techniques face challenges such as under or over placement of proppants, leading to reduced conductivity and production issues due to unpropped zones near the wellbore, which result in partial or complete closure of fractures and decreased hydrocarbon flow.
Innovation Solution
A method and system that involve designing an initial stimulation plan to create a propped fracture, measuring wellbore parameters, determining unpropped fracture volume, and performing a second stimulation to place proppant in the unpropped zone, using a rock bending model to calculate the necessary proppant volume and pressure to reopen and restore connectivity without disrupting existing proppant placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If proppant is injected into the fracture during hydraulic fracturing, then fracture conductivity is improved, but proppant may be over-displaced or under-placed leading to unpropped zones near the wellbore
Solution Approach 1:
The patent applies preliminary action by first creating the fracture and placing initial proppant, then performing a subsequent re-stimulation treatment to place additional proppant in the near-wellbore region. This two-stage approach ensures proper proppant placement by addressing placement deficiencies after the main fracturing operation, thereby preventing unpropped zones that would reduce conductivity.
2Quantity of substance
If displacement fluid is used to transport proppant into the fracture, then proppant placement is achieved, but proppant may be overflushed away from the wellbore region
Solution Approach 1:
The patent employs feedback by monitoring fracture pressure during the fracturing operation to detect when proppant has been overflushed from the near-wellbore region. When pressure drops indicate proppant transport beyond the desired location, the treatment is adjusted or stopped, and a subsequent re-stimulation is planned to restore proper proppant placement based on the observed conditions.
3Productivity
If pressure is released rapidly after injection, then production flow is initiated, but proppant may be transported back into the wellbore causing fracture collapse
Solution Approach 1:
The patent applies preliminary anti-action by performing a re-stimulation treatment that places additional proppant in the near-wellbore region before production begins. This pre-placement of proppant creates a protective barrier that prevents fracture collapse and proppant transport back into the wellbore when pressure is subsequently released during production initiation.
4Loss of time
If conventional single-stage fracturing is performed, then treatment time is reduced, but unpropped zones near the wellbore reduce overall production efficiency
Solution Approach 1:
The patent applies segmentation by dividing the fracturing treatment into two distinct stages: an initial fracturing operation that creates the fracture and places primary proppant, and a subsequent re-stimulation treatment that places additional proppant in the near-wellbore region. This segmentation allows each stage to optimize for its specific purpose, ensuring complete proppant coverage and maximizing production efficiency despite the extended treatment time.
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 effectively targets and reopens unpropped zones, enhancing hydrocarbon production by restoring fracture conductivity and connectivity with the wellbore, thereby improving overall production efficiency.
Implementation Method 1
hydraulic fracturing in which stimulation fluid is injected into a formation to generate or open fractures
Implementation Method 2
a proppant, for example sand, is added to the stimulation fluid so that when injection stops, the fractures that have been created close upon the proppant to form highly permeable channels
Implementation Method 3
using a rock bending model to calculate the necessary proppant volume and pressure to reopen and restore connectivity
Data Source
AI summary
The present disclosure relates to a method for stimulating a subterranean formation that includes performing an initial stimulation in a wellbore positioned within the subterranean formation to place a designed volume of a first proppant in fractures, determining a near wellbore fracture width of the fractures, determining an unpropped fracture length of the fractures based on a rock bending model, determining an unpropped fracture volume based on the unpropped fracture length and near wellbore width of the fractures and performing a second stimulation treatment to place a proppant in fractures in an amount equal to the unpropped fracture volume. This operation allows to restore the conductivity of fracture in the damaged zone.