OptiFrac

Brief

optiFrac is a fracture design optimization tool.

For the given set of reservoir and propane properties it calculates maximum achievable well productivity index and required fracture geometry.

Typical applications

• Single Well Fracture Design and Sensitivity Studies
• Optimum fracture design parameters determination:
  • Dimensionless productivity index, J_D .
  • Dimensionless Fracture conductivity, C_fD .
  • Fracture half length, X_f .
  • Fracture width, w .
  • Fracture penetration, I_x .

Main features

• Plot of J_D as a function of C_fD and I_x as parameter.
• Plot of J_D as a function of C_fD and N_p as parameter.
• Design optimization curve which corresponds to the maximum J_D values for different N_p.
• Design Optimum Point at which the dimensionless productivity index, J_D, is maximized for the given proppant, fracture and reservoir parameters.
• Physical constraints envelope.
• Proppant library with predefined proppant properties.
• Users Data Worksheet for benchmarking vs actual.

Interface features

PEngTools pqPlot

• Save and share references to saved models with colleagues
• Last saved model on current computer and browser is automatically opened
• Choose between Metric units and US oilfield units
• Save as image and print plot by means of chart context menu (button at the upper-right corner of chart)
• Download report in pdf format containing input parameters, calculated values and plot
• Select and copy results to Excel or other application

Used correlations

Type of problem	Correlation	Reference
Oil well VLP	Hagedorn and Brown + Griffith	Hagedorn, A. R., & Brown, K. E. (1965). Experimental study of pressure gradients occurring during continuous two-phase flow in small-diameter vertical conduits. Journal of Petroleum Technology, 17(04), 475-484.
Gas well VLP	Gray	Gray, H. E. (1974). Vertical flow correlation in gas wells. User manual for API14B, subsurface controlled safety valve sizing computer program.
Dry gas VLP	Fanning	Cullender, M.H. and Smith, R.V. 1956. Practical Solution of Gas-Flow Equations for Wells and Pipelines with Large Temperature Gradients. Trans., AIME 207: 281.
Oil well inflow	Composite IPR based – Vogel equations taking into account water	Kermit E. Brown "The Technology of Artificial Lift Methods" Vol. 4 Production Optimization of Oil and Gas Wells by Nodal System Analysis, p. 30, section 2.227.1
Gas well inflow – backpressure equation	Rawlins and Schellhardt	Rawlins, E.L. and Schellhardt, M.A. 1935. Backpressure Data on Natural Gas Wells and Their Application to Production Practices, Vol. 7. Monograph Series, USBM.
Gas well inflow – pseudo-pressure equation using Jd and kh values	Real-gas pseudopressure equation	See for example: Ahmed, T., & McKinney, P. (2011). Advanced reservoir engineering. Gulf Professional Publishing.
Liquid loading	Turner	Turner, R. G., Hubbard, M. G., and Dukler, A. E. (1969) “Analysis and Prediction of Minimum Flow Rate for the Continuous Removal of Liquids from Gas Wells,” Journal of Petroleum Technology, Nov. 1969. pp. 1475–1482.
Erosional velocity	Guidelines from API RP14E	Mokhatab S, Poe WA, Speight JG (2006) "Handbook of Natural Gas Transmission and Processing", Section 11.6 - Design Considerations on sales gas pipelines, subsection 11.6.1 - Line Sizing Criteria, Elsevier, 2006.

PVT correlations are the same as in PVT tool.