Articles

The influence of HTI anisotropy on microseismic event location – a case study from a tight gas field in British Columbia

Zuolin Chen, Barbara Cox and Colin Perkins

VTI anisotropy has been proven to have a large impact on the location accuracy of microseismic events associated with hydraulic fracture monitoring (e.g., Erwemi et al., 2010, Maxwell et al., 2010 ). However, the influence of HTI anisotropy on microseismic event location has rarely been taken into consideration and measured.…

Unintentional Seismicity Induced by Hydraulic Fracturing

Shawn Maxwell

Hydraulic fracturing normally creates only small magnitude events: the microseismicity that is often used to image the fracture growth. These weak microseismic events have magnitudes less than zero, and are often challenging to even detect on surface let alone be felt. However, concern is rising associated with hazards associated with…

A low-frequency downhole sparker for borehole seismic applications

Werner M. Heigl, Robert P. Radtke, Robert H. Stokes, David A. Glowka

We report on the development of a downhole sparker source that is able to generate acoustic signals with peak frequencies between 2 and 1000 Hz. The sparker can be configured such that the energy of the produced acoustic signals lies within a spectral band that is suitable for transmission lengths…

Evolution of marine acquisition technology after wide azimuth

Nick Moldoveanu

Seismic exploration in the deep-water Gulf of Mexico was based for many years on the 3D acquisition method and, as a result, significant oil discoveries were made and most of the plays were found below salt or in intrasalt-body basins. The quality of the seismic data acquired in deep-water subsalt…

Introduction to the special section on ‘Seismic Attributes’

Satinder Chopra

Seismic Rock Physics of Bright Amplitude Oil Sands – A Case Study

Niranjan C. Nanda and Anil K. Wason

Two bright amplitude seismic anomalies, on drilling, tested normal grade oil. However, the association of oil with bright amplitudes in the area, where such seismic signatures are known to be habitually associated with gas, was intriguing and provoked a study of seismic rock physics for the two oil sands.

Geologic controls on seismic amplitudes

Jarrod Dunne

Seismic amplitudes (and AVO) can be used to derisk an exploration prospect; to characterise a reservoir; or to enhance production. By now, seismic amplitude interpretation should be regarded as a mature science, yet examples of its application with demonstrable business impact are rare. All too often, and usually with 20/20…

Some current workflows in shale gas reservoir characterization

Satinder Chopra, Ritesh K. Sharma and Kurt J. Marfurt

With the emergence of the shale gas resources as an important energy source, the characterization of mudrocks has gained significance. To be a good resource, mudrocks need to contain sufficient organic content and respond effectively to hydraulic fracturing. Variations in total organic carbon, as well as brittleness which is a…

Acquisition modeling: expect the unexpected

Carl Regone

A seismic acquisition method that is successful in one area sometimes fails in another, and attempts to fix the problems in processing do not always work. The success in recent years with alternative acquisition schemes has shown the need for ongoing experimentation in acquisition design. However, in 3D seismology, the…

Quantitative Seismic Interpretation

Brian Russell

When I was first asked by John Fernando to be the RECORDER special editor for the theme: Seismic Inversion / Time-lapse / Rock Physics, my first thought was that I was being asked to put together the “theory of everything” in exploration seismology. Come on, John, what topics have you…

A Gassmann-consistent rock physics template

Brian Russell

In an unpublished CREWES report, Russell and Smith (2007) use measurements from Han (1986) to evaluate two different approaches to the modeling of Kdry versus porosity in clean sands: the pore space stiffness method and the critical porosity method. For the range of porosities found in the Han sandstones, Russell…

Joint simultaneous inversion of PP and PS angle gathers

Dan Hampson and Brian Russell

We present a new approach to the joint simultaneous inversion of PP and PS angle gathers for the estimation of Pimpedance, S-impedance and density. Our algorithm is based on three assumptions. The first is that the linearized approximation for reflectivity holds. The second is that PP and PS reflectivity as…

Clarifying Dataroom Confusion

J. Douglas Uffen

Geophysical datarooms are an important element of business in the resource industry. They are staged for many reasons such as: when a company undertakes a sale process of assets or properties, during a Show & Tell presentation, or a farm-in process to attract new investors. Confidentiality Agreements (CAs) are often…

The Interpreter’s Guide to Depth Imaging

Scott MacKay

Compared to time migration, depth imaging should yield simpler structure, higher spatial and vertical resolution, and a more stable phase response. It is also the appropriate input for inversion and other attributes that estimate reservoir properties and mitigate risk. However, the interpreter must actively guide the depth-imaging process to ensure…

Introduction to Unconventional Gas

Manika Prasad

Recent years have brought a rapid expansion of activities around shale gas. The successes in shale gas exploitation have been mainly attributed to advances in engineering. In particular, hydraulic fracturing has contributed immensely towards this success. To date, geophysics has yet to assume a major role in the development of…

Assessing Knudsen flow in gas-flow models of shale reservoirs

Utpalendu Kuila, Manika Prasad and Hossein Kazemi

Shale reservoirs are characterized by extremely small pores and very low permeability. Detection and quantification of these small pores is a challenge. Furthermore, in such small pores, the gas flow need not flow in a Darcy flow regime. The Knudsen diffusion and slip flow gain significance and might account for…

Characterization of sandstone reservoirs using Poisson impedance inversion

Ritesh K. Sharma and Satinder Chopra

We demonstrate the application of Poisson impedance (PI) inversion for characterizing sandstone reservoirs encased in shale, when the impedance contrast between them is very small. Poisson Impedance is defined as the difference between the P-impedance (IP) and a scaled version of the S-impedance (IS), where the scalar (c) can be…

Conventional approach for characterizing unconventional reservoirs

Ritesh K. Sharma and Satinder Chopra

Shale resources characterization has gained attention in the last decade or so, after the Mississippian Barnett shale was successfully developed with the application of hydraulic fracing and horizontal drilling. For characterization of shale gas formations different workflows using 3D surface seismic data have been introduced. We propose an integrated workflow…

Estimating the value of Geophysics: decision analysis

Lee Hunt

This paper discusses the value of geophysical data in the resource play paradigm. Specifically, it shows how well known decision analysis techniques can be applied to estimate the value of seismic for resource play examples. We examine the sensitivity to the accuracy of the seismic interpretation and to the spread…

Elucidating Paleo Depositional Environments from 3D Seismic ‘Solving for One Part of the Hydrocarbon Accumulation Puzzle’

Trevor Johnson

Seismic data has been utilized in oil and gas exploration since around 1928, with early efforts directed at revealing the gross structural and trap configuration in what was then the frontier areas.

However, over the intervening time the technique has been continually refined and improved upon with modern 3D prestack…