AAPG Bulletin: August 2026
ISBN: 9780891810802
Cover to Cover: 88 pages

ARTICLES

Predicting performance
With the paucity of exploration performance tracking studies in the peer-reviewed literature, this paper serves as an example of ways to assess predictive accuracy and determine what lessons can be shared. From a 52-well North Sea United Kingdom Continental Shelf multiyear multioperator exploration portfolio, an overestimation of prospect resource size and slight underestimation of the number of discoveries combined to generate an overall subpar predictive performance for this mature area.

Calculating solubility
The authors present calculations of calcite solubility as a function of temperature using the trends of partial pressure of carbon dioxide and salinity with temperatures typical of many petroleum-producing basins. These results are presented within the framework of a general review of what is known about subsurface calcite solubility and how this applies to processes of both burial cementation and dissolution causing changes in the porosity of petroleum reservoirs.

Analyzing characteristics
The discovery of the Qingyang gas field in the southwestern Ordos Basin, China, following more than 50 yr of petroleum exploration, has generated significant scientific interest in its origins, gas-generation mechanisms, and sources. This paper delves into gas genetic type, thermal maturity, source, and the influence of secondary alteration by analyzing the geochemical characteristics of the gas and comparing it with tight sandstone gas found in other parts of the Ordos Basin.

Modeling accuracy
This work is devoted to the generally stark difference between quantitative diamondoid analysis (biomarker/diamondoid) concentration plots for conventionally versus unconventionally produced oils and the reasons for these differences. Combining biomarker and diamondoid source correlations allows for a much-improved understanding of oil provenance, migration history, and reservoir-filling history. This, in turn, can result in more accurate basin models and the recognition of new plays, even in mature basins.