Bulletin Article


Sandstone pressures follow the hydrostatic gradient in Miocene strata of the Mad Dog field, deep-water Gulf of Mexico, whereas pore pressures in the adjacent mudstones track a trend from well to well that can be approximated by the total vertical stress gradient. The sandstone pressures within these strata are everywhere less than the bounding mudstone pore pressures, and the difference between them is proportional to the total vertical stress. The mudstone pressure is predicted from its porosity with an exponential porosity-versus-vertical effective stress relationship, where porosity is interpreted from wireline velocity. Sonic velocities in mudstones bounding the regional sandstones fall within a narrow range throughout the field from which we interpret their vertical effective stresses can be approximated as constant. We show how to predict sandstone and mudstone pore pressure in any offset well at Mad Dog given knowledge of the local total vertical stress. At Mad Dog, the approach is complicated by the extraordinary lateral changes in total vertical stress that are caused by changing bathymetry and the presence or absence of salt. A similar approach can be used in other subsalt fields. We suggest that pore pressures within mudstones can be systematically different from those of the nearby sandstones, and that this difference can be predicted. Well programs must ensure that the borehole pressure is not too low, which results in borehole closure in the mudstone intervals, and not too high, which can result in lost circulation to the reservoir intervals.

Explorer Article


AAPG once again will have a strong presence at the annual Offshore Technology Conference (OTC), set May 5-8 at the Reliant Center in Houston. 


If you want to know about the Eagle Ford play in Texas, AAPG member Art Donovan is a man you want to be talking to.


Robert G. Loucks, a senior research scientist at the Bureau of Economic Geology, University of Texas at Austin, is one of this year’s Robert R. Berg Outstanding Research Award winners. 


Geology-in-Space promises new frontiers in energy and in the economy. 


Houston grew into the energy capital of the United States, and possibly the world, through more than a century of growth. But its fate as an energy center was seeded in the space of just 125 days, in a story of disaster followed by discovery.


Online registration is open for this year’s AAPG Annual Convention and Exhibition, which will be held April 6-9 at the George R. Brown Convention Center in Houston – and reduced registration fees are still available for those who act fast.

Explorer Emphasis


If you’re a geologist who recognizes that you need to get up to speed on seismic technology, or a geophysicist with a yen to understand the geologic concepts needed for seismic interpretation, Bruce Hart may be the go-to guy for you.


Seismic data is an important asset in finding sweet spots in shale plays, as AAPG member Joanne Wang discussed at a recent workshop.


Seismic Outlook: After several years of plenty, 2014 is expected to be a comparatively lean year for the seismic industry, a few localized hot-spots around the world notwithstanding.


Rio de Janeiro Brazil 14 May, 2014 15 May, 2014 1502
Rio de Janeiro, Brazil
14-15 May 2014

Join the discussion with leading operators in Latin America and Africa. Gain greater understanding of geological and geophysical attributes of stratigraphic traps in deep water settings. Learn more from equatorial margin exploration analogues.

Coming Soon

Check back often. "Find an Expert" feature is coming online soon!

Coming Soon

Check back often. "Find an Expert" feature is coming online soon!

Martha Lou Broussard Martha Lou Broussard Advisory Counselor (2011-2014) Rice University (713) 348-4492
William Martin Whiting William Martin Whiting Advisory Counselor (2013-2016) Consultant (504) 947-8495
Mary Broussard Mary Broussard President (2013-2014) Freeport-McMoRan Oil & Gas 337.354.5041
Charles Alan Sternbach Charles Alan Sternbach Vice President (2013-2014) Star Creek Energy Company Inc (281) 679-7333
Michael Joseph Quinn Michael Joseph Quinn Convention General Chair (2013-2014) Freeport-McMoran Oil & Gas (337) 354-5032
Thomas C. Klekamp Thomas C. Klekamp Past President (2013-2014) Amber Resources, LLC +1.985.630.2480
Steve H. Hill Steve H. Hill Treasurer (2012-2014) Decker Operating Company (713) 880-4343

The House of Delegates of the AAPG is made up of delegates from affiliated societies and international regions throughout the world. They are selected by popular vote from within their respective areas and serve a three year term.

Who Is My Delegate?