What is the correlation between EUR's and Conductivity?

It has been long recognized that the best natural sand for use as proppant in hydraulic fracturing is composed of mono-crystalline quartz grains that have undergone millions of years of weathering in high energy environments including deserts and nearshore beach settings. And the recognized best in class sand for use as proppant in North America, which today we refer to as Northern White Sand ("NWS"), are the pure quartz arenites of Cambro-Ordovician Age found in the Upper Midwest. Unfortunately, NWS are located far from their final point of use in the shale basins and typically have shipping costs that can add an additional $30 to $60 per ton to the well completion costs. Which brings us back to the recent industry acceptance of cheaper, finer-grained, lower quality, regional sand.

In my post of December 12, 2018, we looked at the economics of a 16% increase in BOE EUR when replacing NWS for Texas Gold (as a proxy for Regional Sand) based on better well performance when utilizing higher quality proppants (i.e. resulting from the higher crush, sphericity & roundness and lower acid solubility & turbidity) due to the proppant's pack ability to keep fractures open while maintaining conductivity. More specifically, this is reflected for example in the conductivity numbers of 40/70 mesh sand as a 102 md-ft difference between Covia's NWS (342 md-ft) and Covia's Texas Gold (240 md-ft) at 8000 psi closure stress which results in a 16% difference in EUR.

Shown below is a 40/70 mesh conductivity comparison of eight commercial sands available for purchase (the test results were downloaded from the internet from producer spec sheets) which shows: 1) a tight band of five NWS (1 of these series is from Covia, 4 of these series from other producers), 2) one Covia Texas Gold sand, and 3) two Permian Dune Sands ("PDS"). Note that both of the PDS conductivity series plot far below that of both NWS and Texas Gold. So a reasonable working hypothesis might be, if the PDS conductivity results are in fact representative of West Texas sand production on the whole, at pressures that require an 8K sand the resulting EUR's for PDS will be even lower than that attained by utilizing the Texas Gold. All of which enforces our belief that current sand pricing ignores the inherent differences in conductivity of NWS and Regional Sand and the resulting EUR's, which is what we are really after in the first place.

The inevitable disclaimer. All sand is not created equal. The sand deposit, mining method, process circuit, operations people, the supply chain all matter and do effect product quality.