AAPG Middle East Geoscience Technology Workshop, Integrated Emerging Exploration Concepts

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Exploring and Evaluation of Paleozoic Saudi Arabian Sand for Proppant Applications

Abstract

Hydraulic fracturing activities that was started in 1949 has been dramatically increased over the past few years which has been resulted in a huge demand of quality sand to be used as proppant. The increasing demand has created also a supply and demand gap. This study presents results on experimental works on Saudi Arabian sandstone for possible use as proppant especially local sand of northern and central Saudi Arabia, as well as the comparison in characteristics of equivalent sandstone from south Saudi Arabia. This work includes the characteristics of Paleozoic sandstone in the light of characteristics of proppants and research on the laboratory experiments. A total 27 represented sandstone samples from 8 different locations were collected for this analysis which includes the Paleozoic Siq, Quweira and Qasim formations as well as their members Sajir, Kahfah. Samples preparations included disaggregation and washing. For grain size analysis, X-ray particle size analyzer was used after that the selected samples were sieved using API ISO 19C stack to make the representative. Clean sand was graded to sieve size distributions of 20/40, 30/50 and 50/70 for detailed qualitative and quantitative analysis. Bulk density was measured for every sample, microscopic analysis was done to determine the sphericity and roundness of the sands using Krumbein and Sloss chart. Crush test was performed on18 selective sand samples following API recommended practice 56 and ANSI/API 19C applying 2000 and 3000 psi pressure. Finally Scanning Electron Microscope (SEM) and EDS analysis were done to know surface morphology and mineralogy. Sieve analysis revealed that Siq formation of two locations is 20/40 and 40/70 representative have bulk density of 1.395 gm/cc and 1.397 gm/cc. Crush tests at 2000 and 3000 psi pressure respectively, first one produced 18.34 % fine but second one produced 5.76 % of fine at 2000 psi whereas 40/70 representative sample produced 12.37% of fine at 3000 psi. Most of the samples of other formations were 30/50 representative and were produced more than 10% of fine at 2000 psi. Only five samples were produced less than 10% fine at 2000 psi but more than 10% at 3000 psi. Bulk density of most sand samples is 1.38 to 1.41 gm/cc which is lower than the equivalent sand of South Saudi Arabia (Wajid Group, Bulk density 1.68 gm/cc). SEM analysis reveals enormous fracture and dissolution features on the sand surface which may be due to the oxidation and longtime chemical reaction due to surface exposure that reduces their bulk density. The analyzed sand samples of Siq, Quweira and Qasim formations are fine to medium grained and moderately sorted. Different depositional environment is responsible for their variation in texture (grain size, sorting and shape). Siq formation was deposited directly on the basement as braided stream deposits, Quweira is fluvial to intertidal deposits, Sijir member is fluvio-marine and Kahfah member has been deposited in shallow marine to near shoreface environment. Other controls like origin of detrital sources, tectonics, climate, weathering and transport history played a role as well on these variations. In conclusion it can be said that Paleozoic sand of South Saudi Arabia of Wajid group (Fluvial, shallow marine and glacial deposits) is better than the sand of Central and Northern Saudi Arabian in terms of strength. But these sands can be used as low graded frack sand for hydraulic fracturing. Certain exploratory and evaluation measures might be needed and introduced for selection of suitable sand resources. This can be by identifying sand from certain detrital sources that having optimum recycling and weathering history. This is in addition to introduce some necessary processing and treatment to improve the Saudi natural sands quality.