Meeting Information

"Impact of Experimental Studies on Unconventional Reservoir Mechanisms"

Richard Rosen
Consultant

Novel apparatuses have been developed to measure permeability using steady- and unsteady- state methods on nano-Darcy (nD) shale (source rock) using intact cylindrical samples returned to isostatic effective reservoir stress. The steady-state method uses a high pressure dual pump system using supercritical fluids. High pressure supercritical fluids have low viscosity and low compressibility. The effect of low viscosity fluid results in measureable flow rates and the effect of low compressibility fluid minimize unsteady-state transients thereby reducing the amount of time required to achieve steady-state equilibrium. Specially designed and configured pump systems, seals and sleeves reduce leak rates to allow Darcy flow and permeability determination below 1 nD. The unsteady-state method is based upon standard designs but is optimized for small pore volume. In this report we present a summary of over 200 such permeability measurements. Permeability is observed to be dependent on geologic parameters, such as, texture and composition. Stress dependence, with hysteresis, is observed for samples with and without fractures as is rate dependent skin (Forchheimer). An interpretation model where matrix storage feeds a progressively larger fracture network provides a logical basis for a dual-porosity reservoir simulation model. This dual-porosity model is used to understand the influence of reservoir production parameters, such as choke management.

An additional observed effect is possibly related to pore collapse and disconnection. Pores associated with organic matter are softer than the surrounding mineral matrix. If these pores have a sufficiently small throat diameter, it is not hard to envision that they easily compact and close under increased effective stress as the result of reservoir depletion. Therefore, organic pore systems can become isolated unlike those of a sponge where fluids remain in pressure communication at all times. The implication of such pore isolation phenomena is that fluid material balance is not preserved during production and can contribute to large production decline rates.

From the President

Suzanne Heskin

Happy Holidays!  As I sit by the fire watching more snow fall on the feet already fallen, I can't help but feel grateful for all that we have. While the last year has been rough, we all still have much to be thankful for. The Holiday Season will soon wrap up and we will head into 2016. It's anyone's guess as to what the year will bring, but positive attitudes and hard work certainly can't hurt. Predictions and forecasts may or may not be correct, just as the weather predictions here, forecasting another few feet of snow.

From the Vice President - Technology

Bob Cluff (The Discovery Group)

Our Spring 2016 luncheon program is now full, kicking off with this month's speaker, Rich Rosen, formerly with Marathon Oil Company and now an independent consultant here in Denver, speaking on the impact of experimental studies on unconventional reservoir mechanisms.  Our February speaker will be Jennifer Market with Weatherford on Untangling Acoustic Anisotropy, another SPWLA distinguished lecture.  And for March we have Dr. Siddharth Misra from the University of Oklahoma who will be presenting his recently completed doctoral work on the impact of pyrite, graphite and other conductive minerals on the induction log response in mudrocks.  We'll have speakers from Halliburton and Mt Sopris Instruments to fill out the rest of the year.

Preparations for the Spring topical conference are proceeding with about ½ of the program in place.  Topic will be Petrophysics of the Spraberry-Wolfcamp play in the Midland basin.  The workshop will be held on April 21^st at the Colorado School of Mines student center.  If you have seen or know of a good operator presentation on this topic please contact me as I'm still trying to fill out the program.

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