What Information Is Still Missing After Seismic?

By Ervin M. Kraemer

For decades, seismic exploration has been one of the most valuable tools available to the oil and gas industry.

Modern seismic methods can provide detailed information about subsurface structure, faulting, reservoir geometry, and stratigraphic relationships. These datasets help geologists and geophysicists identify potential traps, evaluate reservoir geometry, and better understand subsurface conditions.

Seismic can be an important part of an exploration program.

However, one question often remains after the seismic interpretation is complete:

Is there evidence that movable hydrocarbons are actually present within the prospect?

That question is important because identifying a favorable structure and identifying hydrocarbons are not necessarily the same thing.

The Remaining Question

Once a prospect has been identified, operators begin evaluating risk.

Questions may include:

• Is the structure properly formed?

• Is reservoir quality adequate?

• Is a seal present?

• Has hydrocarbon migration occurred?

• Is there evidence of hydrocarbons within the target interval?

These are not always simple questions to answer.

As a result, many operators seek additional information before drilling decisions are made.

Where PL24 Fits

The PetroLocate® PL24 system was developed as a seismoelectric exploration tool designed to directly image the presence of resistive fluids that may be associated with hydrocarbon accumulations.

Unlike many conventional exploration methods, the PL24 is not designed to image rock formations, fault systems, structural traps, reservoir geometry, or subsurface structure.

Instead, the system is designed to respond to the presence of resistive fluids within the subsurface.

This distinction is important.

Many exploration methods are designed to identify geological conditions that may be favorable for hydrocarbon accumulation. The PL24 was developed to evaluate resistive fluid anomalies that may be associated with hydrocarbons themselves.

The system is not intended to replace geology, seismic interpretation, reservoir engineering, or drilling. Rather, it is intended to provide an additional dataset that can be evaluated alongside existing geological, geophysical, and engineering information during prospect assessment.

A Different Approach to Exploration

The PL24 is not attempting to determine whether a geological structure exists. Other exploration methods have long been used for that purpose.

The PL24 was developed to answer a different question:

Is there evidence of resistive fluid within the target interval?

By focusing on fluid response rather than structural imaging, the PL24 provides information that may assist operators in evaluating prospect potential before drilling capital is committed.

Depending upon geology and site conditions, the system is capable of investigating targets to depths approaching 3,000 meters (approximately 9,800 feet).

Data acquisition can typically be performed with a relatively small field crew and without the extensive land clearing, vibroseis fleets, large seismic acquisition programs, or significant environmental disturbance often associated with conventional exploration activities.

Exploration Risk Reduction

The purpose of a PL24 survey is straightforward:

To help reduce exploration risk before drilling.

No responsible exploration professional should suggest that any technology guarantees drilling results.

However, informed decisions are generally better than uninformed decisions.

The PL24 was developed to provide additional information that may assist operators in evaluating fluid potential before the drill bit enters the ground.

The most successful projects are often those where operators integrate multiple sources of information, understand the strengths and limitations of each method, and make disciplined decisions based upon the totality of the available data.

The purpose of exploration is not simply to generate maps, collect data, or drill wells.

The purpose of exploration is to improve decision-making and in an industry where drilling costs can be substantial, informed decisions matter.

About the Author

Ervin M. Kraemer is the founder of AquaLocate® and PetroLocate®, author of Water Well Drilling: A Comprehensive Guide to Proper Construction and Seismoelectric Exploration: A Practical Guide to Direct Fluid Detection. For more than 25 years, he has trained and consulted with operators and clients involved in groundwater and hydrocarbon exploration projects throughout the United States and internationally.