A guide to land seismic survey design

Survey design has a significant impact on the success, risk, and costs associated with land seismic acquisition. To help set your next seismic survey up for success, consider these 3 points:

1. Assure sufficient budget and time is allocated to the Geophysical team responsible for creating the technical specifications to assure accurate bids are submitted for consideration

This will pay dividends when it comes to the acquisition contractors designing an accurate survey acquisition plan and commercial model that will minimise project and commercial risks. As a minimum, the following information should be available to the contractor within this document:

• Survey objectives

• Survey location (plus available GIS data)

• Survey type

• HSE risks and requirements

• A summary of the local knowledge of the area, key restriction zones, environmental challenges, land compensation levels, permitting challenges

• Survey size and limits

• Identification of weather or acquisition windows and expected completion date

• Acquisition program summary and parameters (inclusive of design, receiver and source parameters, offsets and azimuths, recording parameters, noise levels etc)

2. Encourage the contractor to conduct “Scouting” during the bid process to minimise risk of “Contract Variation Orders”

A good contractor should conduct a Scouting of the environment and topography of the seismic survey area. The Scouting is important to fully understand and account for the landscape, logistical considerations, operational efficiencies, commercial contingencies, the number of people required, equipment needed, etc in their bid.

“GIS Modelling” is a critical success factor to this process and should always be used as a technique to accurately convert the real world to the digitally and logically represented spatial objects, consisting of the attributes and geometry.

It is good practice to request the contractor to show evidence of their “Scouting Report”, with the GIS Modelling results included, to demonstrate they are familiar with the survey area. They should have a strategy in place to minimise all potential challenges that could occur during the acquisition. This should be inclusive of, but not limited to:

• Means of access

• Local facilities

• Main and fly-camp locations

• Climatic conditions

• Communication infrastructure

• Potential or known access restrictions

• Landowners in agricultural areas

Very often, further efficiencies are unlocked post-contract award, where a second on site Scouting exercise or deep dive has been conducted. The objective is to fully investigate landowner requirements and additional restrictions to determine further opportunities to improve operational efficiency. This exercise should be considered for surveys that are located on complex terrains, where there are likely to be more challenges during acquisition.

3. Don’t be constrained by only using receiver equipment that you have “always used”

Nodal seismic receiver technology is beginning to penetrate the marketplace due to advances in technology and the industry’s need for lower cost, and more environmentally friendly seismic solutions. However, cabled-based receiver equipment is still a solution of choice for some countries and companies.

There could be some reluctance to adopt Nodal technology due to a few reasons:

With operators increasingly requiring denser surveys, at a lower price, with reduced environmental footprint and less HSE risk, it is crucial for companies to remove specifications related to the seismic receiver equipment in the tender documentation. Leverage the experience of the seismic contractors and open up opportunities for them to propose alternative solutions. The objective is to get a better understanding of the available options to acquire seismic in the most efficient and cost-effective way.

Small, light autonomous nodes are proven to be highly reliable seismic equipment that can be deployed with ease in all terrains, can free the survey design from spread restrictions and inefficient receiver roll limitations, allowing, in some scenarios, to achieve super dense surveys when the sources are as unconstrained, and in other scenarios, to compensate for the constraints or limitations imposed on source access and density.

Lower cost nodes are also becoming more accessible to small acquisition contractors, who have greater cash flow challenges compared to multi-national companies. Managing cash flow has always been a challenge for land seismic contractors. Using systems that are cheaper to lease, easier to mobilise, require less people and support infrastructure, will be a big benefit to contractor’s cash flow modelling, and will ultimately offer operators a more cost-effective solution. This will also allow operators who mandate surveys to have a wider vendor list and support localisation initiatives, where the use of local providers and labour is given a higher priority.

Don’t rule nodes out from the onset! They will reduce your exploration risks and costs and the ability to deliver higher density, better subsurface imaging.

• Concerns over the reliability of getting the desired results from fully autonomous nodes

• The need to conduct live QC of the data being harvested

• The desire to utilise existing stocks of cheap, depreciated cable systems instead of purchasing or leasing new nodal systems – meaning adoption of new nodal systems are often seen as not economically viable

• A mindset of “don’t fix something that’s not broken”