Explorer Policy Watch

As shale gas development has boomed over the past decade and public concern about its safety has swelled, both regulatory agencies and operating companies have accelerated their efforts to improve environmental safety.

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

A valuable study funded by the Texas Water Development Board sets aside the controversy and takes a closer look at hydraulic fracturing and water resources and consumption.

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

The ultra-deepwater Alaminos Canyon area proved to be a valuable lease purchase in the recent Gulf of Mexico Lease Sale.

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

Accurate characterization of unconventional reservoirs requires an integrated, multi-faceted approach.

American Association of Petroleum Geologists (AAPG)
Explorer Policy Watch

Starting in 2012 and continuing through this fall, the National Academies (NAS) are hosting workshops to inform the public about shale gas development. 

American Association of Petroleum Geologists (AAPG)
Explorer Geophysical Corner

Last month in this space we analyzed the relations of fracture patterns and layer curvature in clay models. This month we examine these relations in a central Oklahoma field developed by Pathfinder Exploration, Norman, Okla.

American Association of Petroleum Geologists (AAPG)
Explorer Director’s Corner

You don’t have to spend much time around the oil and natural gas industry to understand that it is political.

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

The supergiant Mamba gas discovery has proved East Africa's potential is real.

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

Latin America offers some of the most promising and most perplexing exploration prospects on the planet.

American Association of Petroleum Geologists (AAPG)
American Association of Petroleum Geologists (AAPG)
VG Abstract

Production from unconventional petroleum reservoirs includes petroleum from shale, coal, tight-sand and oil-sand. These reservoirs contain enormous quantities of oil and natural gas but pose a technology challenge to both geoscientists and engineers to produce economically on a commercial scale. These reservoirs store large volumes and are widely distributed at different stratigraphic levels and basin types, offering long-term potential for energy supply. Most of these reservoirs are low permeability and porosity that need enhancement with hydraulic fracture stimulation to maximize fluid drainage. Production from these reservoirs is increasing with continued advancement in geological characterization techniques and technology for well drilling, logging, and completion with drainage enhancement. Currently, Australia, Argentina, Canada, Egypt, USA, and Venezuela are producing natural gas from low permeability reservoirs: tight-sand, shale, and coal (CBM). Canada, Russia, USA, and Venezuela are producing heavy oil from oilsand. USA is leading the development of techniques for exploring, and technology for exploiting unconventional gas resources, which can help to develop potential gas-bearing shales of Thailand. The main focus is on source-reservoir-seal shale petroleum plays. In these tight rocks petroleum resides in the micro-pores as well as adsorbed on and in the organics. Shale has very low matrix permeability (nano-darcies) and has highly layered formations with differences in vertical and horizontal properties, vertically non-homogeneous and horizontally anisotropic with complicate natural fractures. Understanding the rocks is critical in selecting fluid drainage enhancement mechanisms; rock properties such as where shale is clay or silica rich, clay types and maturation , kerogen type and maturation, permeability, porosity, and saturation. Most of these plays require horizontal development with large numbers of wells that require an understanding of formation structure, setting and reservoir character and its lateral extension. The quality of shale-gas resources depend on thickness of net pay (>100 m), adequate porosity (>2%), high reservoir pressure (ideally overpressure), high thermal maturity (>1.5% Ro), high organic richness (>2% TOC), low in clay (<50%), high in brittle minerals (quartz, carbonates, feldspars), and favourable in-situ stress. During the past decade, unconventional shale and tight-sand gas plays have become an important supply of natural gas in the US, and now in shale oil as well. As a consequence, interest to assess and explore these plays is rapidly spreading worldwide. The high production potential of shale petroleum resources has contributed to a comparably favourable outlook for increased future petroleum supplies globally. Application of 2D and 3D seismic for defining reservoirs and micro seismic for monitoring fracturing, measuring rock properties downhole (borehole imaging) and in laboratory (mineralogy, porosity, permeability), horizontal drilling (downhole GPS), and hydraulic fracture stimulation (cross-linked gel, slick-water, nitrogen or nitrogen foam) is key in improving production from these huge resources with low productivity factors.

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American Association of Petroleum Geologists (AAPG)

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