[First Hit]

Datapages, Inc.Print this page

Economic Significance of Fluvial Sandstones within the Fruitland Formation, San Juan Basin, New Previous HitMexicoNext Hit*

By

Kuwanna Dyer1 and James M. Perkins1

 

Search and Discovery Article #10110 (2006)

Posted September 18, 2006

 

*Oral presentation at Rocky Mountain Section, AAPG, meeting, Billings, Montana June 11-13, 2006.

 

Click to view presentation in PDF Format (~10.4 mb).

 

1BP America Production Company, Houston, TX ( [email protected] ).

 

Abstract 

Fluvial sandstone beds are intercalated within the prolific Fruitland Formation coal intervals in the western portion of the San Juan Basin, New Previous HitMexicoNext Hit. These sandstone intervals are often disregarded as primary or even secondary completion targets, particularly in the Type I and Type II coal areas that dominate the coal trend. Within the Type III coal areas in the southwestern part of the basin, however, where productivity from the coal interval is lower, these sandstones can be an important resource. Subsurface mapping within the BP-operated Gallegos Canyon Unit (GCU) shows significant down cutting into the thinly-bedded, coaly intervals, juxtaposing the porous (6 - 22%) and permeable sandstones with the coal source beds. Production for these shallow wells, which are less than 1200 feet in depth, ranges from 0.001 to 1.7 BCFG. Total cumulative production from 50 completions is 18 BCFG. Subsurface Previous HitmapsNext Hit are compared to outcrops within the Bisti area, which is 25 miles south of GCU, and these provide clear examples of the down cutting and aerial distribution of reservoir-quality sandstones. The next step in realizing the economic potential of the Fruitland sandstone involves expanding the subsurface map downdip further into the basin, carefully identifying and mapping prominent sandstone bodies. Assuming an average recovery of 0.25 BCF/well, the impact of the Fruitland sandstone completion program could be in excess of 100 BCFG.

 

Selected Figures 

Map of  San Juan Basin, with location of  BHP San Juan coal mine and Gallegos Canyon Unit.

Lower coastal plain in block diagram, illustrating depositional environment of Fruitland Formation.

Upper Cretaceous time-stratigraphic chart, showing position of Fruitland Formation.

Fruitland sandstone lenses and associated coals in BHP’s San Juan coal mine.

Type log, Fruitland sandstone, Gallegos Canyon Unit #331, a Fruitland sandstone productive Previous HitexampleNext Hit.

Net sandstone isopach map, Gallegos Canyon Unit.

  

Conclusions 

  • Fruitland sandstones are interbedded with mature, gas-generating coal intervals.

  • The sandstones are deposited as point and medial bars in a lower coastal plain environment, proximal to a well developed marine shoreline complex.

  • Average cumulative production to date is about 0.4 BCF, though recoveries can be in excess of 2.5 BCF.

  • The Fruitland sandstones provide an often overlooked, shallow potential ‘behind pipe’ target, enhanced by improved completion techniques.

 

Acknowledgments 

BP America Production Company, David Reese, Bill Pelzmann, Richard Pomrenke, and Glenn Zinter.