D A Vertical Well With 5 In Hole Diameter Is Drilled Into A Shale Reservoir To A Depth Of 10 000 Ft The Reservoir Has 1 (199.4 KiB) Viewed 45 times
(d) A vertical well with 5 in hole diameter is drilled into a shale reservoir to a depth of 10,000 ft. The reservoir has a drainage radius of 1000 ft. You have been provided with the following information on the properties of reservoir: Permeability: Poisson's ratio: Poro-elastic constant: Average density of overburden formation: Pore pressure gradient: Tectonic stress: Shale tensile strength: 0.01 md 0.45 0.7 150 lb/ft3 0.45 psi/ft 1700 psi 1400 psi (0) Calculate the breakdown pressure of the reservoir. [4 marks] (ii) The above well has been hydraulically fractured which resulted in a fracture width of 0.1 inch and fracture permeability of 100,000 md. If the fold of increase (ratio of increase in the flow rate) in well productivity becomes 15 as a result, calculate the total length of the fracture and the dimensionless fracture conductivity. Assume the reservoir has a drainage radius of 1000 ft, the pay zone height does not vary after fracture and an initial skin factor of 0. [8 marks] Use the assumptions and equations on page 5 in calculations where needed
12 Data for Q3: Overburden stress, psi: Ov = pH/144 Otect : tectonic stress, psi Effective overburden stress, psi: o y = Ov - a Pp v: Poisson's ratio Effective horizontal stress, psi: p: the average density of Oh 0 overburden formation, Ib/ft3 1 - V H: well depth, ft Total horizontal stress, psi: Oh = o'n + a pp a: poroelastic constant The maximum horizontal stress, psi: Oh, max =Oh, min + otect Pp: pore pressure, psi Breakdown pressure, psi: pb = 30h, min - Oh, max + To - Pp To: tensile strength of the rock, psi Dimensionless fracture conductivity: kew FCD kx; kr. fracture permeability, md k: formation permeability, md w: fracture width, ft xf. fracture half-length, ft 141.2uB [in (..) Fluid flow rate, bbls/day: kh[Pe - Pwf] qf +S B: formation volume factor u: fluid viscosity, cp K: rock permeability, md h: pay zone height, ft rw: radius of well, ft re: radius of drainage, ft Pwr: pressure of flowing well, psi Pe: pressure at the constant-pressure boundary, psi Effective skin factor: Sf = 0.7 – In Xf rw
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