C&P: “Fracture Spacing, Well Spacing and Fluid Selection in Pad Fracturing of Horizontal Wells”

Speaker: Dr. Mukul M. Sharma
Speaker Dr. Mukul M. Sharma
Mukul M. Sharma is Professor and holds the “Tex” Moncrief Chair in the Department of Petroleum and Geosystems Engineering at the University of Texas at Austin where he has been for the past 28 years. He served as Chairman of the Department from 2001 to 2005. His current research interests ...

Mukul M. Sharma is Professor and holds the “Tex” Moncrief Chair in the Department of Petroleum and Geosystems Engineering at the University of Texas at Austin where he has been for the past 28 years. He served as Chairman of the Department from 2001 to 2005. His current research interests include hydraulic fracturing, oilfield water management, formation damage and improved oil recovery. He has published more than 300 journal articles and conference proceedings and has 12 patents. He founded Austin Geotech Services an E&P consulting company in 1996 and co-founded Layline Petroleum and Karsu Petroleum private E&P companies in 2006. Sharma has a bachelor of technology in chemical engineering from the Indian Institute of Technology and an MS and PhD in chemical and petroleum engineering from the University of Southern California.


Among his many awards, Dr. Sharma is the recipient of the 2009 Lucas Gold Medal, SPE’s highest technical award. He is also the recipient of the 2004 SPE Faculty Distinguished Achievement Award, the 2002 Lester C. Uren Award and the 1998 SPE Formation Evaluation Award. He served as an SPE Distinguished Lecturer in 2002, has served on the Editorial Boards of many journals, and taught and consulted for industry worldwide.

Full Description

This talk addresses some recent advances in answering four key questions that arise when pad drilling and completing wells in unconventional plays:

  1. What is the optimum fracture / cluster spacing and sequencing?
  2. What is the optimum well spacing?
  3. What is the optimum wellbore trajectory for maximizing IPs and long term production (including artificial lift)?
  4. Where is the frac water going, what is its impact on well productivity and EUR?

The creation of a hydraulic fracture and production or injection of fluids into the producing formation changes the stress distribution in the rock. This stress shadow can influence the growth of subsequent fractures and have a significant influence on well IP and EUR. By analyzing the net pressure, radioactive tracer, fluid returns and microseismic data from pad drilled wells, we show that stress interference between fractures and between wells occurs routinely and leads to fracture reorientation. We propose that the stress shadow created by the propped fracture and the associated induced unpropped (IU) fracture network decreases over time. The hydraulic fracture and the induced unpropped fractures close as a result of fluid leak-off resulting in a reduction in the spatial extent of the stress shadow. This makes subsequent fracture stages less susceptible to fracture interference and more efficient (by avoiding the wastage of fluid / proppant into pre-existing fractures networks). This suggests that increasing the time between successive fractures in a wellbore will lead to improved fracture performance. This provides, for the first time, a reasonable explanation of why zipper fracs work better than conventional fracs. However, our work suggests that there may be other fracture sequencing strategies for accomplishing this even more effectively.

A general geo-mechanical modeling framework (UT-Multifrac) has been used to analyze and integrate field pressure, rate, microseismic, tracer and production data. It is shown that pressure data obtained during fracturing can be used as a diagnostic tool to study fracture interference. After the model has been calibrated and validated with field data, it can be used to perform pad-scale simulations to determine optimum fracture spacing and well spacing while properly accounting for both mechanical and poroelastic stress interference effects. Simulations can be run to analyze the impact of important formation properties and fracture design parameters. These simulations can be used for making operational decisions for drilling (well spacing, infill drilling), production (avoiding frac hits) and completion (frac spacing, sand volumes, fluids, sequencing) for a particular reservoir environment.

                Fluid selection and flowback control are shown to influence the performance of pad fraced wells. Our ability to efficiently flow back both frac water and reservoir liquids is key to good well performance. Simulations and field performance data are used to show how this flowback is controlled by fluid selection, flowback choke control and wellbore trajectory. Simulations are run using UT-Pipeflow and a reservoir simulator and compared with PLT results to select the appropriate wellbore trajectory and predict the clean-up and performance of wells completed toe-up and toe-down for different fluid environments.

Organizer Jonathan Godwin

Contact: (281)921-6526 or jgodwin@carboceramics.com


Wed, Feb. 26, 2014
11:30 a.m. - 1 p.m. America/Chicago

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