Explorer Article

California dreaming: Some people see the Monterey Shale, and think “oil.” Others, however, see a slippery challenge.

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

Closest of trends: Geoscientists experienced a huge “aha!” moment that started with the realization that Pennsylvania’s Marcellus Shale and Texas’ Eagle Ford Shale have a lot in common.

American Association of Petroleum Geologists (AAPG)
Explorer Regions and Sections

September will be a busy month for the AAPG Sections – two groups will be holding their annual meetings, both in locales that boast geologic industry history and plenty of entertainment opportunities. 

American Association of Petroleum Geologists (AAPG)
Explorer Geophysical Corner

The discrimination of fluid content and lithology in a reservoir is an important characterization that has a bearing on reservoir development and its management.

American Association of Petroleum Geologists (AAPG)
Explorer President’s Column

An average of four dry holes are drilled through a giant field before the discovery is recognized, according to AAPG Sidney Powers Medalist Robert M. Sneider.

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

A new study assesses the potential for recoverable unconventional resources in Poland.

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

Say you want a revolution … Unconventional resources have dominated the energy news in various parts of the world. Is Asia next?

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

Recount: The U.S. Geological Survey offers a new estimate of the world’s undiscovered conventional oil and gas resources.

American Association of Petroleum Geologists (AAPG)
Explorer Emphasis Article

A world-class technical program is in place for the AAPG International Conference and Exhibition in Singapore.

American Association of Petroleum Geologists (AAPG)
Explorer Division Column EMD

For more than 100 years, shale oil has referred to the product of pyroly­sis of oil shale, whereas oil shale refers to organic rich (kerogen) rock that has never reached the oil window.

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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