Improving underground gas storage deliverability with 3D seismic

Through close collaboration with our client, understanding their objectives and applying our knowledge and experience of the area, RPS custom-designed and optimised a 3D seismic program and end-to-end workflow that enabled Enbridge, formerly Union Gas, to significantly improve the injection and withdrawal efficiency of an underground gas storage project in Ontario, Canada.

RPS reviewed the previous seismic data available to Enbridge in the region and found that it was 25 years old and low resolution when compared to what was possible with modern acquisition and planning. The low-grade illumination and resolution made the data unsuitable to identify the fully optimised new drilling locations Enbridge sought in order to increase deliverability of future wells. Working with Enbridge, we demonstrated that the cost of properly planning and implementing an end-to-end seismic workflow would considerably de-risk future well placement and be recouped quickly with the increase in deliverability of the stored gas when needed.

A successful survey starts with integrated and pragmatic approach

Seismic project planners and interpretation specialists at RPS determined that significant improvement in the subsurface image and subsequent interpretation could be achieved by acquiring new 3D seismic data. Seismic survey designers took an integrated and pragmatic approach using the analysis of historic data to fully optimise the new survey design. The team considered both the geophysical and logistical challenges the survey acquisition team would face in the field. They worked closely with the seismic operational and interpretation team to design a survey that balanced project costs while meeting the technical requirements to achieve the project goal.

End to end seismic project management

Acting on behalf of our client’s procurement department, RPS seismic project managers tendered, evaluated and awarded contracts for the various third-party services required in the field. Leveraging the long-standing relationships RPS project managers have established with various contractors over hundreds of projects, they negotiated prices and terms and acted as the single point of contact for Enbridge during the survey. By taking the prime contractor role, RPS reduced company management time and overhead. RPS project managers oversaw the financial management, reporting, execution, and closure of the required contracts. Throughout the actual survey, project managers worked continuously to ensure contract compliance.

Safety first

A critical part of the project manager’s role in every project is to bridge the client’s safety program and RPS’ certified safety program. The RPS project manager provided monitoring documentation and reports throughout stages of the survey, informing Enbridge, ensuring compliance and delivering the project safely and efficiently. This seismic survey, with a total of 6,366 project hours, was completed with zero safety incidents.

The data delivers

With the data acquisition complete, seismic data specialists at RPS oversaw the loading and processing of both the historical data and the recently acquired data. These specialists work closely with the data processors to ensure that the processing runstream applied maximises the subsurface illumination. The new data provided a substantial enhancement in the imaging of the reef. The delineation of the reef edge and the detail and confidence in the mapping of internal reef geology variations was substantially increased. In an effort to increase the benefits of the data and increase temporal resolution, interpretation specialists also conducted a post-stack inversion to highlight low-impedance zones within the reef, likely indicative of enhanced porosity. Higher porosity provides higher permeability and an increase in the total gas volume that can be stored in the reservoir as well as increased return flow-rates when gas is most urgently needed.

Five existing wells had been drilled in the region previously. Based on the enhanced data and the improved understanding of the reef geometry and reservoir characteristics, RPS collaborated with Enbridge to select the location of three new gas storage wells with confidence. On average, the three new wells showed substantially higher flow rates and subsequently lower cost per unit of deliverability over the existing wells. Enbridge’s prime objective of locating optimal drilling targets was successfully achieved, with the new wells providing a substantial increase in the gas storage deliverability from the reef. The increased rate of return from the improved deliverability quickly recovered the cost of the 3D seismic survey and moved the project into improved free cash flow. Ensuring that the design and delivery of the end-to-end seismic program was continuously tested against the achievement of the project objectives meant that the upfront investment in replacing existing data produced a far superior result, both technically and commercially, than continuing to rely on the old data simply because it was already there. RPS – Making Complex Easy.