Joint Annual Technical Meeting of the Petroleum Branch of AIME Student Chapters of the University of Texas and A. and M. College, 14–15 February, Austin, Texas


Conventional core data for defining reservoir fluid contacts, total pore storage space, permeability distribution and permeability to a single phase fluid have been In general use for many years. The development of reservoir analysis as a science required specific information on the properties of the reservoir fluids and the reservoir rock. Experience has shown that the rock properties affect productive characteristics and recovery more than the fluid properties.

Additional tests, frequently referred to as special core analyses tests, have been developed to provide the information required for reservoir analysis. Capillary pressure-saturation relationships, when used with conventional data, permit determination of the interstitial water content and the original distribution of fluids. Gas-oil relative permeability tests provide data to study the simultaneous flow of gas and oil. Various types of water flood tests are made to evaluate the displacement of oil by water.

The results of studies on many reservoirs show that the pore size and the pore size distribution affect markedly both the oil-in-place and the oil recovery. Information is presented to illustrate variations in oil-in-place, as determined from capillary pressure-saturation relationships, for three types of reservoirs where pore geometry is the only major variable. Ranges in recovery to be expected by solution gas expansion and by water flooding are also presented. The wide ranges in recovery estimates illustrate the marked effect of pore geometry and demonstrate the necessity of obtaining specific data on each reservoir being studied for accurate engineering evaluation.

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