American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Evansville, Indiana, September 21 and 22, 1967. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

Abstract

The Guernsey storage field, located in Guernsey and Coshocton Counties, has been in operation since June 1954. The field consists of 53 wells completed in the Oriskany formation at an average depth of 3100 feet.

With increased utilization of the field, a gradual decline was detected in the ability of the wells to take gas or deliver gas. In the spring of 1964 an extensive program was initiated in an attempt to rectify the plugging problem. The wells were watered with approximately 50 gallons of fresh water, allowed to stand for at least 24 hours, then a bailer sample was procured. All samples were tested according to A.P.I. standards. Every sample contained general bacteria populations and almost all samples indicated iron oxide, iron sulfide or hydrogen sulfide. The sulfate reducing bacteria had not produced hydrogen sulfide of significant quantities, however the by-products of biological growth attributed greatly to the plugging incurred in the wells.

A treating program was initiated to reduce the bacterial contamination. A mixture of bactericide, alcohol, and water was injected into the wells during the input cycle. The treating fluid was of significant value in lowering surface tension, giving a wide volume kill, corrosion inhibitor, dissolve salt buildup, cleaning the formation of debris, and reducing residual water saturation.

In analyzing the results of the treating program, the open flow deliverabilities for 1964 (before treatment) were compared to the 1966 open flows (after treatment). The data showed an open flow increase in approximately 80% of the wells. With this definite improvement it is certain the bacterial growth caused the plugging and the treatment proved effective in restoring the wells to their original potential.

Introduction

The Guernsey Storage Field of the Ohio Fuel Gas Company is located in four adjoining townships in Guernsey and Coshocton Counties of Eastern Ohio. The 53 storage wells are completed in the dense Oriskany sandstone at an average depth of 3300 feet. The majority of the wells were drilled in the 1940's for native production and were utilized as such until 1954 when needed storage capacity necessitated converting the field to storage operations. Additional wells were then drilled to unify spacing and increase utilization of installed pipelines and equipment.

The wells are completed either open hole or cased and have flow strings ranging from 3 1/2 inch tubing to 7 inch casing. Drillers logs and Radioactive logs show a sand thickness of 4 to 12 feet with low porosity and permeability. An impervious limestone overlays and underlays the Oriskany to prohibit any migration of natural gas.

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