The Neil burg McLaren reservoir zone consists of tabular Lower and Upper McLaren Sands separated by a thin coal. The two sandstone reservoirs do not aggregate more than 7m in thickness. The main trapping mechanism for the Lower Sand is formed by erosional channels filled by shaly and cemented rocks.
The Lower and Upper Sands differ in several ways:
the Lower Sand is a troublesome sand producer whereas the Upper sand is not;
the Lower unit is typically very coarse silt whereas the Upper unit is very fine sand;
the Lower Sand is less uniform in grain size and contains more clay size material but it has a larger porosity and a sizeable permeability;
the main clay minerals are kaolinite in the Lower Sand and illite in the Upper Sand.
It appears that the Lower Sand is quite devoid of cementing material because of changes, especially leaching, that occurred after deposition (diagenesis). Several reservoir and geotechnical properties are much affected by diagenesis and these changes in Lloydminster type sands should receive more research attention.
This paper concerns the Neilburg McLaren pool where sizeable reserves of heavy oil occur in tabular sandstones having an aggregate thickness of less than 7 metres. The pool has unique and individual features, including a productivity toward production of loose sand, but in many respects it is not atypical of the numerous pools that produce from thin sheetlike sandstones in the Lloydminster heavy oil belt.
Work leading to this report was done through a Sand Control Studies project conducted jointly by the University of Regina and the Saskatchewan Heavy Oil Laboratory (now SRC Petroleum Division). The work was carried out under the Canada/Saskatchewan Heavy Oil/Fossil Fuel s Agreement. Major objective of the study was to develop an understanding of the basic mechanism of sand production in the Lloydminster heavy oil belt. Work done by Richardson led to a B.Sc. Honours thesis l at the University of Regina. A progress report concerning mainly stratigraphy and trapping mechanism was published by Richardson and Vigrass2 in 1984. A contract report, with Pappas and Vigrass3 as principal authors, has been submitted to the Saskatchewan Department of Energy and Mines.
The reservoir Zone at Neilburg consists of a NcLaren Lower Oil Sand, which is topped by an underclay and thin coal seam, and a thin McLaren Upper Oil Sand. The pool occurs on a structural high but the main petroleum trap for the Lower Sand is formed by erosional channels filled with shaly and cemented rocks. There are several distinct differences between the Lower and Upper Sands:
The Lower Sand is a troublesome sand producer whereas the Upper Sand is not.
The Lower McLaren is typically very coarse silt whereas the Upper McLaren is very fine sand.
The Lower Sand is less uniform in grain size and contains more clay size material but it has a larger porosity and a sizeable permeability.