Alberta's Drilling, Gas Reserve Additions, And Gas Supply And Demand
Authors: Samson L. , Kirsch M.-A. 
Published: March 2010

Abstract
Future successful development and exploratory drilling for gas will have to exceed current levels. Only three pools have been discovered in. the last ten years that have initial marketable reserves of greater than 1,500 E6M3. A positive correlation exists between the addition of gas reserves in the province of Alberta and the amount of exploratory drilling. Development drilling conducted for deliverability purposes does not substantially add to the reserve picture. However, exploratory drilling may result in large reserve additions. Future reserve additions translate into gas supply. By conducting scenario analysis of reserve growth based on ultimate potential estimates of 5,600 E9M3 (200 Tcf) and 7,600 E9M3 (270 Tcf), and comparing the results with current reserve growth levels, an assessment can be made of the province' sability to meet future market demand.

Introduction
In this analysis outpost wells have been included as development wells. Exploration wells include: deeper pool test, new pool wildcat, new field wildcat and crude bitumen evaluation. Unsuccessful, service, suspended, junked and abandoned wells have been excluded. The remainder of the wells are deemed to be successful wells(1).
Beginning in 1972 successful drilling activity in the province increased until 1980. From 1981 to 1992 there was a general downward trend in drilling activity with exceptions occurring in 1985 and 1988. Drilling in 1992 was at its lowest level since 1975 at 2,635 wells. Drilling activity in 1993 started on an upward trend that continued through to 1997. In 1994, for the first time in its history, more than 6,000 successful wells were drilled in the province. In 1997, over 11,000 successful wells were drilled, 11,036 to be exact! (Figure 1)
Two questions that are often asked are:"With such a large increase in successful drilling activity in the province, why do we not see more gas reserves being added?" and,"Will the future gas reserve additions be sufficient to meet market demand?"
To answer the first question we need to dig a little deeper by exan1ining the split between development and exploratory drilling, the average-drill depth of development and exploratory wells, the per cent of drilling for gas and the type of exploratory drilling being done. A search can be made for any correlation between the type of exploratory drilling and the size of the gas reserves added.
The answer to the second question can be approached in two ways. By examining the historical average annual and cumulative gas pool size, an estimate of the number of successful gas wells needed to meet future demand can be made. In addition, by assuming an ultimate potential reserve and a specific time frame for the development of that reserve, an annual growth rate curve necessary to achieve that ultimate potential can be estimated. Comparing the annual growth rate to an estimated market demand gives a picture of if that demand can be met.
In presenting this material, we will first begin with the total drilling activity and then concentrate on gas drilling and its impact on supply.