Gas Production And Decline Rates In the Province of Alberta

Abstract

Abstract In excess of 6,400 new gas wells per year will be required to meet future demand, well above the current tie in levels. Total deliveries of gas from the province of Alberta increased by 56% to 127 E9M3 from 1990 to 1997. Pipeline expansions in late 1997 to 2000 are expected to add a further 26 E9M3. The. total demand by 2002 is expected to reach 177E9M3... A study was conducted to examine the decline trend ofgas wells over the last eight years with a view to predicting the future tie in requirements and the ability of Alberta to meet the increasing demand for gas. The study showed that new sources of gas < are coming on at rates of less than 30 E3M3/D and gas wens rates are declining at 27% the first year. Using the gas well productivity and performance results of the study, predictions were made of future tie in requirements. Introduction In 1997, total deliveries of gas from Alberta wells amounted to 127 E9M3, an increase of 56% over 1990 values. The volumes exported to the US almost doubled (Figure 1)(1). The Northern Border Pipeline and the TransCanada Pipelines expansions in late 1997 and 1998, and the Alliance Pipeline in 2000 are expected to add another 31 E9M3 to the annual demand for gas from the Western Canada Sedimentary Basin of which 26 E9M3 will come from Alberta. The EUB estimates that the annual total deliveries of gas from Alberta in 2002 will be 177.4 E9M3. Part I-Producing Gas Well Statistics In order to accommodate the increase in production, an increasing number of gas wells have been tied in. At year-end 1997 there were 43,262 producing gas wells (Figure 2), 13,491 more than in 1990. There was a net increase of 3,600 wells in 1994, 1,800 in 1995, 1,900 in 1996 and 3,200 in 1997(2). From 1994 through to 1997, more gas wells were being placed on production than in any previous year. In 1994, 4,456 wells were placed on production and in 1997,4,529 wells were placed on production (Figure 3). Gas Well Replacement By comparing the total number of gas wells placed on production in a given year with the incremental net increase in the number of gas wells on production, the number of new wells that replaced gas wells ceasing production can be determined. As expected, as the number of wells placed on production increased, the number of wells ceasing production in anyone year has increased. Over 1,300 wells ceased production in each of the last three years (Figure 4). The average proportion of gas wells required to replace wells ceasing production over the past ten years was 44.8% and over the last three years 39.5%. Tie in Time for Gas Wells From Finished Drill Date New wells are being tied in at a faster rate but there is still a significant elapsed time before some wells are placed on production.