EKT Interactive: Oil and Gas Exploration Types of Seismic Surveys

Seismic surveys play a pivotal role in Oil and Gas exploration, including in identifying wildcat wells. While the world of seismic surveys is intricate, there are three fundamental types of technology used: 2D, 3D and 4D. Each has its advantages in assisting Oil and Gas explorers in their quest to open new well opportunities.

In Oil and Gas Exploration Types of Seismic Surveys, EKT Interactive seeks to explain this beneficial technology. Crown Exploration is sharing the piece in full, below, to help our Venturers learn more about the use of seismic surveys throughout the Oil and Gas Industry. For more insights, contact us at 972-395-1133. Your Oil and Gas investment begins with a conversation.

Oil and Gas Exploration Types of Seismic Surveys*

In this lesson, we will continue our discussion on seismic surveys, specifically the different Exploration types of seismic that is used in oil and gas exploration.

Types of Seismic Surveys

A seismic program is expensive and time consuming.  Collecting and processing the data can take 12-18 months.  However, sophisticated computer imaging of subsurface structures can enhance the likelihood of a successful wildcat well. So it is used after a play has shown some promise by the basin analysis and aerial surveys.

There are three basic types of seismic technologies used to help explore for oil and gas – 2D, 3D and 4D. 

Advanced imaging not only helps find and produce oil and gas more efficiently, but has advanced the identification and recovery of important subsalt reservoirs in offshore locations such as the  Gulf of Mexico and Brazil.

• 2D Seismic

2-D seismic is recorded using straight lines of receivers crossing the surface of the earth. A 2-D seismic survey works well for imaging major structures.

2-D surveying is still popular because data gathering and analysis of 2D seismic information is much quicker and cheaper than 3D or 4D.  2-D data requires much less permitting, surveying, and processing time than even small 3D surveys.  Large 3D seismic shoots may take one to two years to acquire, and three to four months to process the information.

• 3D Seismic

The late 1970s saw the development of the 3D seismic survey in which the data imaged was not just a vertical cross-section but an entire volume of earth.

One of the most obvious differences between 2D and 3D seismic is that 3D imaging provides information continuously through the subsurface whereas 2D seismic reveals only strips of information.

Nevertheless, 3D seismic may not be cost-effective in many onshore provinces, especially in the early stages of exploration.  In onshore 3D seismic, many lines of receivers are used and recorded across the earth’s surface.  The area of receivers recorded is known as a “patch”.

In offshore, the main difference between 2D and 3D seismic is that 2D seismic is acquired using a single listening cable towed behind the seismic vessel, whereas 3D seismic is acquired using six parallel listening cables, and the cables can be up to six kilometers long.

3D operations are considerably more elaborate than 2D and the daily cost of the crew is substantially increased.

However, 3D seismic data collection improves exploration performance by allowing for:

• fewer dry holes
• more optimized well locations
• guidance for horizontal drilling projects
• more complete evaluation of mineral rights
• and a better understanding of the nature of the prospects

• 4D Seismic

4D, or time-lapse, seismic is the process of using 3D seismic data acquired at different times, over the same area.

It is used to assess changes in a producing hydrocarbon reservoir over time (the fourth dimension). Changes may be observed in fluid location and saturation, pressure and temperature.

To maximize the value of a 4D seismic project, exploration and production assets are carefully screened because of the expense to acquire and analyze the data.

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* Oil and Gas Exploration Types of Seismic Surveys." EKT Interactive, ektinteractive.com/exploration/oil-gas-exploration-types-seismic/. Accessed 10 Oct. 2023.