Articles
Evaluation of Foothills Natural Gas Plays Using Two Dimensional Balanced Cross Sections
Andrew C. Newson
Exploration for large gas fields in the Foothills has been an important part of many oil and gas companies’ exploration strategies in Canada during the last 5 years. Given the increasing demand for natural gas and the realistic expectation that we will continue to find large natural gas reserves in…
Scientific Anathema: The Black Box
Lee Hunt
The existence of undisclosed or ‘black box’ techniques have long been with us. Black box techniques have historically been offered either to preserve a technological secret, or to provide a cloak in which deception and exaggeration may be perpetrated. One motivation comes from the very understandable desire to protect a…
High-Resolution Crosswell Seismic Imaging Between Horizontal Wells
Guoping Li and Ernest Majer
Crosswell seismology is a proven high-resolution seismic imaging technology due to its ability to provide unusually high-frequencies conventionally unattainable by 3-D seismic. Numerous case studies have demonstrated its applicability as one of the most effective reservoir management tools. A recent report by Zhang et al. (2002), for instance, shows that…
Geophysical Methods Used in Exploration for Gemstones
Frederick A. Cook
Advancements in geophysical methods provide opportunities for applications in exploration and development of many types of gemstone deposits. Mega-scale regional techniques, such as teleseismic signals, regional electromagnetic, and long range controlled source seismology (reflection and refraction) soundings, assist in delineating thick cratonic regions and the internal structure of the lithosphere…
Base Metal Exploration: Looking Deeper and Adding Value with Seismic Data
Larry Matthews
The search for mineral resources in the crystalline crust has become increasingly challenging as the need to explore deeper becomes an economic reality. Canadian mining camps continue to deplete their historical reserve base from decades old surface discoveries or deepening mine extensions. Ongoing efforts are focused toward developing technologies capable…
Finding Nickel from the B-Field at Raglan – ‘To B or not dB’
Richard T. Osmond and Anthony H. Watts, William R. Ravenhurst, Catherine P. Foley and Keith E. Leslie
Based on test work over known Ni-Cu sulphide deposits, in Sudbury (Watts A., 1997, King A., 1994) as well as Voisey’s Bay (Balch S.J., 1998), it has become increasingly clear that pyrrhotite hosted sulphide deposits possess conductances on the order of 100 kS to 10,000 kS and even greater depending…
Crosswell Seismic Profiling: The Decade Ahead
Jerry M. Harris
For many years Crosswell seismic profiles (XSP) have promised high-resolution images for purposes of reservoir characterization and monitoring. Designed to fill the gap in coverage and resolution that exists between surface seismic and borehole logs, the crosswell seismic profile has overcome numerous hurdles in technology development, operations, and commercialization. Where…
Natural Gas Hydrates: Permanent Earth Constituents Impacting Sediment Strength and Continental Margin Evolution
Allen Lowrie, Carol Lutken, Erika Geresi, Richard H. Bennett, Richard Faas, Tom McGee
Natural gas hydrates are crystalline structures that combine natural gases and water under appropriate temperature and pressure conditions. Natural gases and water are found throughout the Solar System, even in interplanetary space. It is geologically reasonable to conjecture that these natural components were incorporated into the proto-Earth and that hydrates…
Integrated Well Log and Reflection Seismic Analysis of Gas Hydrate Accumulations on Richards Island
T.S. Collett and S.R. Dallimore
The subsurface zone in which the pressure and temperature conditions are conducive to the occurrence of gas-hydrates is areally extensive beneath most of the Mackenzie Delta-Beaufort Sea region, with the base of the gas-hydrate stability zone more than 1,200 m deep on Richards Island. In a recent study, gas hydrates…
How AVO Can be a Multiple Attenuator
Jan Dewar
Sometimes there are spin-off benefits to developing a technology. From NASA’s space technology program, for instance, we have benefited from unintended applications such as fireproof suits for auto racers, laser angioplasty, advanced digital imaging for biopsies, and programmable pacemakers. While programmable pacemakers clearly were not directly developed for space travel,…
Recent Developments in Wave Equation Migration
Christof Stork, Uwe Albertin, Clement Kostov, Dave Yingst, Jerry Kapoor
As a result of recent developments, prestack wave equation migration is capable of producing dramatically improved sub-salt images over Kirchhoff depth migration and has become a hot technology in the Gulf of Mexico. It is possible that wave equation migration can help in other high velocity contrast areas such as…
Rock Physics of Geopressure and Prediction of Abnormal Pore Fluid Pressures Using Seismic Data: Part 1
José M. Carcione and Hans B. Helle
Various physical processes cause anomalous pressures of underground fluids in a petroleum province. We quantify the effect on seismic properties caused by the common mechanisms of overpressure generation such as (kerogen-to-oil and oil-to-gas conversion) disequilibrium compaction. Fluid pressure due to kerogen-to-oil conversion in source rock shale significantly reduces the seismic…
Rock Physics of Geopressure and Prediction of Abnormal Pore Fluid Pressures Using Seismic Data: Part 2
José M. Carcione and Hans B. Helle
Various physical processes cause anomalous pressures of underground fluids in a petroleum province. We quantify the effect on seismic properties caused by the common mechanisms of overpressure generation such as (kerogen-to-oil and oil-to-gas conversion) disequilibrium compaction. Fluid pressure due to kerogen-to-oil conversion in source rock shale significantly reduces the seismic…
Seismic Detection and Estimation of Overpressures Part I: the Rock Physics Basis
Nader Dutta, Tapan Mukerji, Manika Prasad, and Jack Dvorkin
This paper describes the rock physics basis of understanding and better defining seismic signatures of overpressures (defined as the pore fluid pressure in excess of the hydrostatic pressure). Our accompanying paper describes applications of these fundamental rock models for estimating pore pressures from field seismic data. The physical basis for…
Seismic Detection and Estimation of Overpressures Part II: Field Applications
Nader Dutta, Tapan Mukerji, Manika Prasad, and Jack Dvorkin
Subsurface formations with pore fluid pressure in excess of the hydrostatic pressure (geopressure) are encountered worldwide. Although there are a multitude of causes that can result in geopressure, under compaction due to rapid burial of sediments is the predominant cause of geopressure. Typically, if the loading process is rapid, fluid…
Challenges Of Porosity-Based Pore Pressure Prediction
Richard. E. Swarbrick
Newly emerging plays with high reserves replacement potential include the deep-water sediments of ocean margins worldwide, sub-salt reserves and high-pressure high-temperature environments, all of which are subject to significant overpressure, that is pore pressures above “normal” or hydrostatic. In each of these environments the pore pressures can reach values as…
Dimensionless Gradients Applied To Pore Pressure Prediction – A New Standard
Martin Traugott and Richard Swarbrick
Given the cost of controlling problems associated with drilling pore pressure surprises, it is important to develop concise methods for predicting pressure gradients ahead of the bit. This paper sets out a new standard for working with gradients and explores the Eaton relationship between gradients and seismic velocity. A main…
Pore Pressure Estimation – What Can We Learn From 4D?
M. Landrø and Øyvind Kvam
Most methods for pressure prediction from seismic are based on detection of low velocity anomalies. The significant growth of time-lapse seismic surveys gives us a possibility to check the robustness and limitations of these classical prediction methods, and might also lead to new methods for pressure prediction that can be…
Sequence Stratigraphy: Key to Geopressure Profile Assessment
Selim S. Shaker
Lithology and principal stress are the main driving mechanisms behind the development of the subsurface geopressure profile. Lithology distribution creates the conditions that lead to compartmentalization. Sequence/seismic stratigraphy are good guide lines to establish the paleoenvironment and sediment’s spatial distribution in a basin. The overburden (principle stress) is a result…
Effects of Stress and Pore Fluid Pressure on Seismic Anisotropy in Cracked Rock
Enru Liu, Simon R. Tod and Xiang-Yang Li
The cracks in sedimentary rock that is subjected to a change in the applied stress or fluid pressure will undergo a distortion related to their orientation relative to the principal directions of the applied stress. Both the crack distribution and the fluid-flow properties will be altered as a consequence of…
