Saudi Aramco has started the development of the first unconventional reservoir in the Middle East, targeting the source rock of the main oil reservoirs in the Kingdom. The completion of an unconventional reservoir requires a fracturing process in each horizontal well, which requires an abundant supply of sand. Therefore, utilizing in-situ dune sand (ISDS) was considered for potential cost savings and lowering CO2 emissions from the reduction of transportation and logistics.

The first location for the ISDS trial was selected by collecting several sand samples from different areas in the field and carrying out sieve analysis and crush and mineralogy tests. The location for the first trial was then selected based on a combination of the highest silica content, fewer impurities, best crush tests, and proximity to the fracturing operations happening at the time. Therefore, an operational trial of ISDS was designed and carried out in two wells of a four-well pad to study the operational feasibility of getting the in-situ sand and filtering the sand to the required mesh size and to determine its impact on good deliverability. Additionally, the trial studied if the in-situ sand was required to be chemically treated to remove impurities. The trial was evaluated based on operational implementation analysis and production performance compared to the other two control wells stimulated with sand from standard operations.

Combining this trial with sandbox technology was decided to facilitate logistics and onsite sand transportation. The in-situ dune sand was sieved onsite, and half of that sand was chemically treated in a nearby facility. Fracturing operations were performed as per design with no complications concerning ISDS. Initial flowback data showed that ISDS wells had similar initial productivity indexes compared to offset standard wells, indicating that ISDS results in good fracture conductivity for the formation rock quality. Full utilization of ISDS may entail moving the sand processing facility to a centralized hub that cuts sand-transport commuting distance by 90%, reducing CO2 emissions in the supply chain of the project. It is expected to decrease sand costs by 30%, equivalent to 6% of the stimulation package cost.

This paper also provides guidance for the industry to explore the controlling properties of sand for fracturing operations. Significant cost savings for the project and some reduction in CO2 emissions could be achieved with ISDS implementation, which will positively impact field development economics.

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