First Break - Volume 41, Issue 1, 2023

To achieve the Dutch policy objective to significantly reduce carbon emissions, a shift from fossil fuels towards renewable energy resources is required. In the Netherlands, geothermal energy is a proven renewable energy resource, but currently only with a limited number of operating installations.

A limiting factor to the broader development of geothermal projects is the fact that the subsurface data in the Netherlands is not well distributed; seismic and well data coverage is poor in roughly half of the country, including major residential and industrial areas with high heat demand. Improving the data coverage in these areas would increase the benefit-risk ratio of geothermal projects.

The key objective of the Dutch SCAN Geothermal Exploration Programme is to collect subsurface data in areas of relative low data coverage to improve the understanding of the subsurface and to reduce geological uncertainties for the development of geothermal projects.

This article discusses the seismic phase of the SCAN programme, which started with the acquisition of a 2D seismic test line to define the optimum acquisition parameters for a regional 2D seismic survey, the acquisition and processing of 1761 km of newly acquired data and a large reprocessing effort comprising close to 7500 km of vintage 2D seismic data.

Reservoir inhomogeneity under hydraulic fracturing operations causes stress variance in the subsurface. Shale reservoirs are generally stress-sensitive. The purpose of this paper is to introduce a new monitoring technology that could lead to the next generation of hydraulic fracture optimisation in shale reservoirs.

While there is no denying that increasing fold and decreasing bin size theoretically equates to improved quality, this comes with a significant increase in costs in the total equipment needed during a survey, its deployment time, and the processing of the acquired data. To offset the cost per square kilometre requires greater productivity (shots per hour/day) and is generally achieved by increasing the number of sources while using some form of simultaneous recording techniques. However, this form of acquisition also increases source-generated noise from the ‘overlapping sweeps’. Is the future of exploration, as predicted by many, an ever-increasing trace count or fold, the only way to improve data quality or are there alternatives? This article is not only a review of current acquisition techniques utilizing vibrators and the resultant expected quality but also alternative methods of acquisition that can improve both productivity and S/N by utilising land impulse sources.

Reducing the widths of seismic cutlines helps to minimise the environmental impact of acquiring seismic surveys. This can be accomplished by utilising miniaturised seismic sources, but not all small sources provide sufficient energy for imaging deeper oil sands reservoirs at the required resolution. In the winter of 2020, two independent 2D field trials were conducted to test the use of miniaturised seismic sources for imaging both shallow and deep oil sands reservoirs in Canada. This case study examines the results for frequency content and potential reduction in environmental impact as compared to conventional oil sands explosive sources. The resolution and signal-to-noise ratio of the seismic records from miniaturized seismic sources were matching and equivalent to the conventional seismic source.

Whilst designing an onshore seismic survey the geophysicist is principally concerned with geophysical parameters, such as the point and line spacing. The survey cost, however, cannot be ignored during this initial stage. In particular, weather can add significant cost to a survey. In this paper we show how the weather-related risk for seismic surveys in the Bowen Basin, Queensland, Australia, can be quantified using historical weather data. As well as allowing quantifiable risk determinations, such analyses can also be used to identify the most appropriate time of the year to acquire data. In the specific example given here we were principally impacted by rain. It is easily conceivable, however, that such analyses could be applied to areas where other weather impacts (e.g., snow) are important.