Analysis of Production Decline Characteristics of a Multistage Hydraulically Fractured Well in a Naturally Fractured Reservoir.

Open Access
Author:
Ketineni, Sarath Pavan
Graduate Program:
Energy and Mineral Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 12, 2012
Committee Members:
  • Turgay Ertekin, Thesis Advisor
Keywords:
  • Unconventional Reservoir
  • Type curve
  • Rate Transient Analysis
  • Mathieu Functions
  • Laplace Transform
  • Stehfest Algorithm
Abstract:
Unconventional hydrocarbon reserves exploration has seen a new high in the recent times owing to the decline in production from conventional reserves. For sustained hydrocarbon production, it is essential for the market to shift from conventional to unconventional sources of energy. Shale gas and tight gas reserves are considered unconventional in nature. Innovative technologies like horizontal well drilling and hydraulic fracturing have made the extraction of hydrocarbons from these unconventional resources economically viable. Most shale gas reservoirs are naturally fractured in nature and exhibit dual porosity characteristics. The flow from these tight gas reserves could accurately be modeled as flow around a horizontal well in a naturally fractured formation. Hydraulic fracturing often alters the reservoir parameters around the wellbore, thus, creating a rubble zone (stimulated reservoir volume-SRV) having different characteristics when compared to the outer zone. This problem could ideally be approximated as flow around a horizontal wellbore in a composite naturally fractured formation. Elliptical flow regime was long considered a transient regime in between radial and pseudo radial flow, but in case of anisotropic reservoirs and low permeability reservoirs (tight gas and shale gas) the elliptical flow regime extends for a considerably large period of time. A solution to the elliptical flow problem that considers flow into a horizontal wellbore in a truly composite naturally fractured reservoir has been attempted. Mathieu’s modified functions were used to solve the elliptical flow problem. The generated solution is validated with other existing solutions by collapsing it into simpler forms given in the literature. Forward solutions are generated for various dimensionless parameters.