Reservoir characterization and stimulation for conventional and unconventional reservoirs

Abstract

Reservoir Engineering provides an understanding of fluid flow and phase behavior for all fluids contained within the reservoir. Thorough understanding of the reservoir is a must in order to optimize its lifetime performance. Many tools and analysis offer us accurate measurements and characterization of the reservoir rocks and fluids. Initial steps include geology, petrophysics, well testing and well logging and formation evaluation. Formation pressure measurement, downhole fluid sampling and analysis along with laboratory PVT analysis are used to build a picture of reservoir potential and predict future performance. Reservoirs can broadly be classified into conventional and unconventional reservoirs. The technique to approach each varies greatly from one another. Conventional reservoirs have been subject to extensive research, including the areas of well test analysis, PVT analysis, Enhanced Oil recovery and well logging, to name a few. Present study deals with the hydrocarbon bearing formations of a type area in Frontier Basin. These fields are characterized by very low porosity, ultra-low permeability and low reservoir pressure. However, large areas of the field have been found to be charged with gas with high calorific value. The area is also characterized by naturally occurring fractures which aid in flow from reservoir to wellbore. Considerable research is devoted to approaches and methods to commercially exploit gas from these reservoirs. Tools like VP/VS analysis, Horner’s plot, Permeability Jail, analysis of relative permeability, water and gas saturation enable us to think of effectively extracting gas from these kinds of reservoirs. Efforts are made to design the well trajectory along the naturally occurring fractures identified using Fracture Analysis. Periodic stimulation of the wells is integral to ensure optimal performance. Such techniques include hydrofracking, acid fracturing, matrix acidization, radial jet drilling and GasGun technology. Case studies and worldwide examples involving use of such techniques have been dealt with in detail, in this report. Present study is a treatise on the same. Outcome of the study will be helpful to ascertain the flow potential from the field.