Fatemeh Belyadi

Fracture Treatment Design

The chapter starts with defining the terms and quantities required for fracture treatment design such as absolute volume factor, slurry and clean frac fluid rates, slurry density, clean and slurry volume for frac stages, stage proppant, sand per foot and water per foot on both stage and well levels, and sand-to-water ratio. For each one of these properties, actual examples are presented and the solution to the problem is explained in detail. Next, a slick water frac schedule is presented with an actual field example. A foam frac schedule and corresponding calculations are presented, including foam and nitrogen volumes, blender sand concentrations, and clean and slurry rate calculations with and without proppants. For each topic, actual field examples and solutions to the problem are discussed step by step.

Hydraulic Fracturing Chemical Selection and Design

This chapter begins with the introduction of different chemicals added to hydraulic fracturing fluid, such as friction reducer (FR), FR breaker, biocide, iron control, and scale inhibitors. The application of linear gel, gel breaker, buffers, cross-linker, and surfactant is also explained. The importance and application of each added component is detailed. Experimental techniques required for chemical selection and optimization, such as a flow loop test is presented. This chapter also provides examples to calculate the friction pressure.

Hydraulic Fracturing Fluid Systems

This chapter starts with a detailed discussion on slick water and cross-linked gel fluid systems and their applications. Next, hybrid fluid systems and their applications in hydraulic fracturing of shale reservoirs are explained. An introduction on foam fracturing including detailed discussions on foam quality and foam stability is also presented. Finally, the concept of tortuosity is explored ending with typical slick water frac steps including acidizing, pad, proppant, and flush stages.

Rock Mechanical Properties and In Situ Stresses

This chapter opens with basic definitions of Young’s modulus, Poisson’s ratio, fracture toughness, and brittleness and fracability ratios. Next, vertical and minimum and maximum horizontal stress, and Biot’s coefficient are explained. This chapter continues with various states of stress and ends with detailed discussions on transverse and longitudinal fractures. Different examples in each subsection on calculating the rock mechanical properties and in situ stresses are provided.

Introduction to Unconventional Reservoirs

This chapter introduces unconventional resources and their importance in improving quality of life. Basic concepts and terms used in the oil and gas industry are introduced and defined, and then expanded to different gas types, natural gas transportation, and usage. Next, the chapter explains the major differences between conventional and unconventional hydrocarbon resources and various characteristics of different unconventional resources such as coalbed methane, tight sands, shale gas, and gas hydrates reservoirs. At the end of the chapter, detailed discussions on shale gas reservoirs, their pore structure, mineralogy, and rock characteristics are presented.

Shale Initial Gas-in-Place Calculation

This chapter introduces the most recent techniques in calculating the original gas in place (OGIP) of organic-rich shale reservoirs. The chapter introduces gas distribution in different pore structures of shale gas reservoirs and different techniques used for OGIP calculations. The effect of adsorbed gas volume and adsorbed layer thickness on OGIP calculations is then discussed. The chapter also outlines analytical and numerical techniques of adsorbed gas density measurements. Examples are presented that clearly show the steps required for OGIP calculations. Finally, the concept of recovery factor is discussed and sample practice is provided.

Advanced Shale Reservoir Characterization

This chapter introduces the advanced techniques in measuring shale rock properties in the laboratory. The chapter begins with different techniques of shale pore-size distribution measurements, including mercury injection porosimetry, nuclear magnetic resonance, and imaging techniques such as focused ion beam scanning electron microscopy. Then it discusses the techniques used for gas sorption measurements, specifically volumetric techniques and the most advanced methods to analyze and perform the experiment. Various shale porosity and pore compressibility measurements are discussed. The chapter concludes with different shale permeability measurement techniques, including steady state and transient measurements of shale core plug and crushed samples.

Fracture Pressure Analysis and Perforation Design

This chapter begins with basic concepts around pressure analysis used in the oil and gas industry including hydrostatic pressure, hydrostatic pressure gradient, instantaneous shut-in pressure, fracture pressure gradient, and bottom-hole treating pressure. Next, total friction including pipe, perforation, and near-wellbore friction pressure is defined. Perforation design and efficiency is also discussed in this chapter. At the end of this chapter discussions are extended to fracture extension pressure, closure pressure, net pressure, and surface-treating pressure.

Operations and Execution

The chapter starts with introduction to water resources and water storage. Various equipment requirements for hydraulic fracturing operations and execution are then discussed and presented such as hydration unit, blender, sand master, T-belt, missile, frac manifold, frac van, and overpressuring safety devices. The chapter then includes discussions on water, sand, and chemical coordination. Next, stage treatment and flowback after screening out tips are presented. Finally, frac well-head equipment is explained including tubing head, lower master valve, hydraulic valve, flow cross, manual valve, and goat head.

Completions and Flowback Design Evaluation in Relation to Production

The chapter begins with basic definitions of landing zone and explains the relationship between number of perforations, entry-hole diameter, and perforation phasing with production data. Other important parameters in completion design, such as having bounded or unbounded well, up dip or down dip well, and well spacing are also discussed. The role of water quality and sand and water per foot in production performance is also another important topic discussed in this chapter. Detailed discussions on flowback design, flowback equipment, and spacing guidelines are presented. This chapter concludes with tubing analysis.