1962 Economic and Valuation Symposium Dallas, March 15–16, 1962

Introduction

The estimation of secondary reserves unfortunately cannot be reduced to a simple, standard procedure wherein all factors or parts are automatically specified once a process has been selected. This paper will discuss the general procedure and factors which must be considered in estimating secondary reserves. Before any discussion pertaining to estimation of reserves, it is necessary to define the terminology.

Reserves, as used herein, is that quantity of oil which is yet to be reduced to possession by the production procedure in operation.

Ultimate or Total Reserves is that quantity of oil which can yet be reduced to possession by either the existing or augmented operational procedure.

Primary Reserves is that quantity of oil which is yet to be reduced to possession soley by means of the naturally occurring reservoir energies under the existing competitive and regulatory conditions.

Secondary Reserves is that quantity of oil in excess of primary reserves which is yet to be reduced to possession by supplementation of the naturally existing reservoir energy.

Ultimate Recovery is that quantity of oil which will be reduced to possession during the operational life of an oil reservoir.

Primary Recovery is that quantity of oil which will or could be reduced to possession in an oil reservoir's producing life utilizing only the naturally occurring reservoir energy.

Secondary Recovery is that quantity of oil in excess of the ultimate primary recovery which will be reduced to possession because of the supplementation of natural reservoir energy. It is the difference between ultimate and primary recovery.

For the foregoing definitions, general equations can be written to express the relationship between ultimate, primary and secondary recovery and primary and secondary reserves. The most general form of these equations are

Ultimate Recovery
=(EA EV Ed)N=(ER)UN
(1)
Primary Recovery
=((Ed) p(EA) p(EV)p)N=(ER)p N
(2)

= (EA) ij (EV) ij (Ed) ij) (N-Np0 pj)

- (ER)p - (ER) pj) N

or

= (ER) ij (N - (Np) pj)

(ER)p N(Np)pj)
(3)

Reserves at time k

=(ER)UN(Np)k
(4)

Primary Reserves at time k

= ((ER)p  (ER) pk) N= ((ER0p N  (Np) pk)
(5)

Secondary Reserves at time k

= (ER)ij (N(Np)pj)((ER)p N(Np)pj)((Np)k(Np)pk)
(6)

P. 36^

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