COPYRIGHT. Nodal Analysis Workshop. Horizontal and Fractured Wells. By the end of this lesson, you will be able to:

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1 Learning Objectives Nodal Analysis Workshop Horizontal and Fractured Wells By the end of this lesson, you will be able to: Accurately represent horizontal well geometry inside SNAP Describe the Joshi equation for horizontal well inflow Accurately represent fractured well geometry inside SNAP Describe a typical frac and possible discrepancies between the traditional frac models, reality, and well performance modeling 1

2 Conventional Horizontal Well Planning Heel Toe Conventional Horizontal Well Performance Several quantitative models exist to predict rate Models have been created by industry leaders Joshi model, Borisov model, Giger model, Babu model Each model uses unique flow geometry Models are useful in early rate planning Favorable vertical permeability drains the thickness h of the producing interval Mathematical flow geometry developed for horizontal flow

3 Vertical vs Horizontal Well Drainage Geometry Top View Conventional Designs Top View Vertical Well Flow Side View Top View Flow Pattern Alteration Horizontal Well Flow Conventional Designs Side View Top View Vertical / Deviated Well Horizontal Well 3

4 Joshi Horizontal Well Flow Equation Horizontal Well Drainage Area b y e = r ev Reservoir Engineering Horizontal Wells L x e = L + r ev Where r ev = drainage radius of a vertical well placed at either end of the lateral Elliptical area a = L/ + r ev b = r ev Area = πab Assumes isotropic horizontal permeabilities Joshi Horizontal Well Flow Equation h δz a k v k h Cross Section View Reservoir Engineering Horizontal Wells

5 Joshi Horizontal Well Flow Equation q H Reservoir Engineering Horizontal Wells a n q H = flow rate, bpd a L k H = horizontal permeability, md k v = vertical permeability, md h = reservoir thickness, ft δp = p res p wf, psi μ = fluid viscosity, cp k B = fluid formation volume factor, rb/stb H L h h Productivity Improvement Factor Rule of thumb for a horizontal well: h p B n L h r w L = lateral length, ft β = k H k v z δ z = distance reservoir midpoint to horizontal lateral, ft a = half major axis of ellipse, ft a = L reh 4 / L 0.5 r eh = horizontal well drainage radius, ft PIF L h k k v h Reservoir Engineering Horizontal Wells

6 A View of a Hydraulic Fracture This is the result of a properly planned & executed fracture job.... This is what fracture computer models theoretically predict. These computer models are used to design frac length, frac width and frac height Frac height---- A View of a Hydraulic Fracture Frac half length Theoretically, this is what frac models predict. 6

7 Fracture Orientation in Vertical and Horizontal Wells Rock will always fracture in a plane perpendicular to the direction of minimum horizontal confining stress... Engineers apply this principle in well and fracture planning psi 6500 psi Well Fracture Program Plan From: Halliburton Shale Well Designed Proppant Filled Fracture Sand Reservoir 7100 psi Shale Water 7

8 Fracture Width Models Proppant Packing 8

9 Proppant Conductivity C f = k f * w f K f = Proppant permeability w f = Fracture width C f = Fracture conductivity, indicates the fracture s ability to flow fluids Proppant is selected to withstand the fracture closing pressure Brown Frac Sand 0/40 Mesh Low Density Ceramic 0/40 Mesh Northern White Frac Sand Curable Resin-Coated Sand 0/40 Mesh 0/40 Mesh Resin-Coated Ceramic 0/40 Mesh Sintered Bauxite 0/40 Mesh Proppants - Permeability and Conductivity w f Proppant In-Situ Permeability, k f Measured in laboratory Can be reduced by crushing, gel residue and fluid some fluid loss additives Average Propped Fracture Width, w f Mainly a function of proppant concentration Can be reduced by crushing and embedment Fracture Conductivity, w f k f Sometimes referred to as FC or Fracture Flow Capacity Units may vary (inches, feet, darcys, millidarcys) kf 9

10 Post Frac... Get the Fluid Off the Formation Post Job, Frac Fluid Retention Must Be Addressed Potential frac face damage Treating Fluid Removal From Fracture Is Critical 10