Lu, Qiao
(2022)
Impact of Weak Interfaces and Layered Rock Properties on Hydraulic Fracture Containment and Height Growth.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Hydraulic fracturing and waterflooding are both widely applied methods for improving the recovery of oil and gas resources. These methods have increasing commonality because many waterfloods are being carried out at high enough pressure to generate hydraulic fractures. Therefore, a common goal is to connect hydrocarbon-bearing layers to the well but impose pressure limits that avoid breaking through into water-bearing layers or otherwise non-producing layers adjacent to it. However, when using classical but highly simplified height growth models, the pressure limits can be far too conservative, leading to much lower recovery rates and inefficient use of resources invested in developing producing reservoirs.
In this context, this research contributes experiments and numerical simulations on the role of stresses, weak interfaces, and mechanical properties of a three-layer system in promoting containment or height growth from a central reservoir to neighboring barrier layers. In all cases, the experiments and simulations agree that the pressure required to induce substantial height growth exceeds the stress applied to the barrier layers and is far above classical predictions. When the reservoir layer is softer than the barriers, the containment is sustained to even higher pressures than for layers with similar material properties. Besides, the experiments show that permeability of the barrier layer can enable containment at higher pressures than at comparable cases with impermeable materials, but with a strikingly more sudden transition to uncontrolled height growth when instability is eventually induced.
In a complementary effort, lattice-type Distinct Element Method (DEM) simulation results show a high level of consistency with experimental lab data. By leading to increased confidence in the model, this comparison suggests it could provide an efficient and sufficiently accurate platform for providing the key link between the laboratory results and the applicability of the work in field-scale operations. Thus, this research comprises a uniquely important step forward in elucidating essential mechanisms that govern hydraulic fracture containment and height growth in layered reservoirs.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
10 June 2022 |
| Date Type: |
Publication |
| Defense Date: |
23 March 2022 |
| Approval Date: |
10 June 2022 |
| Submission Date: |
3 March 2022 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
133 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Civil and Environmental Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Hydraulic fracture; Lab experiment; Numerical Simulation; Three-layer; Height growth |
| Date Deposited: |
10 Jun 2023 05:00 |
| Last Modified: |
10 Jun 2023 05:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/42289 |
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