The AAPG Century – Giant Fields through the Decades, Robert Merrill, June 19, 2017.
A giant oil field is generally estimated to contain in excess of 500 MMBOE estimated ultimate recovery. Since the late nineteenth century, at least four factors seem to control the frequency of discovery of giant oil and gas fields. These factors include concepts (e.g., geological models), technology, price, and access to drilling locations. The importance of understanding these factors drove creativity in the exploration process. In our efforts to understand common petroleum system parameters in these fields and, importantly, what is unusual about each field, leads to “Discovery Thinking” in our search for new oil and gas fields. In the mid- to late-nineteenth century the recognition of seeps focused exploration efforts. This was followed by recognizing the importance of anticlines. Petrophysical tools followed in the early 20th century as well as the application of seismic as an exploration tool. These tools continued to be developed and improved with time and processing advances in the 1970’s significantly improved our ability to image the subsurface and characterize the reservoir. Advances in drilling technology have led us from the land to deep water. The integration of rock mechanics using geology, geophysics, and engineering in this decade led to new workflows for geologists, geophysicists, and engineers to complete wells in reservoirs previously considered too tight for economic production. This integration brought together intensive core analysis and new sample imaging techniques to characterize the pores in low-permeability rocks that we now recognize as basin-wide “unconventional” fields. Traditional roles in discovering giant fields over previous decades included the “rockers” (geologists well versed in reservoirs), the “trappers” (geophysicists mapping the geometry of accumulations), and the “sealers and the sourcers” (explorers following source rock and seals). More than ever, successful giant field discovery in the decade 2000 through 2010 was led by the “integrators.” If you know how to hammer, every problem is a nail. The enhancement of the tools including Basin analysis, geochemistry, cutting-edge seismic imaging, and rock mechanics have become critical additions to the explorer’s skill set. The ingenuity of combined disciplines continues to meet the demands of an energy hungry world. AAPG Memoir 113 documents the fifth decade of the Giant Fields series.