Abstract

The U.S. Department of Energy/Morgantown Energy Technology Center (METC), through partnerships with industry, is demonstrating the importance of geologic modeling and reservoir simulation for optimizing the development and operation of gas storage fields. METC entered into a Cooperative Research and Development Agreement with National Fuel Gas Supply Corporation (NFGSC) to investigate the expansion of an existing gas storage field in western New York.

A geologic model of the reservoir was developed using data from 14 existing vertical wells, mainly concentrated in the center of the field. A good history match of simulator predicted and field measured flowing wellhead pressure was achieved through 2.5 injection and withdrawal cycles. Biannual inventory shut-in pressures were matched within 5 percent.

Forecasts of reservoir performance were made for various field development strategies that included the operation of 11 existing vertical wells plus (1)14 additional vertical wells, (2) four, 2000-foot horizontal wells, and (3) a combination of horizontal and vertical wells.

Although there has been no field verification of the modeling results, the results of the study have shown that geologic modeling and reservoir simulation can be very important to the efficient development of a storage reservoir. The modeling results have shown the possible advantages of using horizontal wells and have also focused efforts to gather additional data necessary to make the final decision on a field development strategy. While cost savings opportunities have been identified through this modeling effort with NFGSC, the need for additional reservoir description will require three to four vertical step-out wells before proceeding with full field development, especially with horizontal wells.

Introduction

A more efficient natural gas storage system will be essential for supporting the expected growth in U.S. gas demand. A mission of the METC Gas Storage and Delivery Program is to assist industry, through cooperative demonstration studies of selected storage fields, to increase storage efficiency, i.e., increase deliverability and capacity, and reduce development costs.

A promising technology for increasing storage efficiency is horizontal wells. Thousands of horizontal wells have been drilled for exploration and production with great success, yet the application of this technology in the storage industry has been very limited. Several horizontal wells that have been drilled in gas storage fields, for which the results have been reported have shown deliverability increases of 4-7 times over vertical wells.

Horizontal wells, however, are not a cure-all and must be carefully studied to determine their usefulness and profitability. Thus, a second objective of the cooperative efforts between METC and industry is to show the cost benefit of using geologic modeling and reservoir simulation to "optimize" field development strategies. The model results have shown the possible advantages of using horizontal well technology and have also focused efforts to gather the additional data necessary to make the final decision on field development strategy.

This content is only available via PDF.
You can access this article if you purchase or spend a download.