Application of the GasGun™ in Kansas Oil and Gas Operations

Dwayne McCune, North Midcontinent PTTC
Richard Schmidt, J Integral Engineering, Inc.

Executive Summary

The frequency of using the GasGun™ to stimulate oil and gas wells in Kansas has increased significantly in the past two years. Explosive stimulation of wells is nearly as old as the oil business. However, the GasGun™ incorporates modern science and techniques to provide a safer, more controllable stimulation, which is also relatively inexpensive.

Kansas operators have applied the GasGun™ in over 240 wells with a wide range of results. The technique has been applied in limestone and sandstone in widely scattered regions of the state. Many wells which were uneconomical have been revived and many years of commercial production is anticipated.

Not all wells are candidates, nor are all treatments successful. The developer of the process has relied upon the successes and failures to establish screening criteria for determining logical stimulation candidates.

Introduction

The GasGun™ is a stimulation treatment for oil and gas wells that utilizes a low, solid- propellant explosive to generate high-pressure gas and create fractures in reservoirs. Developed by J Integral Engineering, Inc., of West Linn, Oregon, and Sandia National Laboratories, the process has had reasonable success in the Illinois Basin and recently, over 240 applications have been conducted in Kansas.

The tool, which is normally run on wireline, contains a solid propellant, that rapidly generates high-pressure gas when it burns. Multiple fractures radiating 10 to 100 feet from the wellbore are created by the progressively-burning propellants, which are much more effective at creating fractures than high explosives such as nitroglycerine.

The GasGun comes in a standard diameter of 3¼” and in lengths of 2, 4, 6, 8 and 10 feet. The treatment can be performed in cased wells or open-hole completions.

The advantages of the GasGun over hydraulic fracturing is that there is minimal vertical growth of fractures, multiple fractures are created, the entire zone is stimulated, there is no need to inject fluids, less equipment is needed, and the cost is much lower. While not considered as a complete replacement for hydraulic fracturing or acidizing, it has applicability in many marginal wells where the expense of a fracture treatment can not be justified, or as an initial treatment prior to acidizing or fracturing.

In Kansas, one operator has been successful in utilizing the GasGun to stimulate tight sections in the Arbuckle, allowing for low-pressure acid treatments. In a recent application, six wells were shot with the GasGun, and only one was considered to be unsuccessful, as it broke into the water zone. Three of the treatments were obvious successes. Over a period of two months, the combined production of the three wells rose from 8.7 BOPD prior to treating to 30 BOPD. Due to the relatively inexpensive cost of the treatments, payout often occurs in days or weeks. The operator is continuing to monitor the wells and will soon be performing similar treatments on additional wells.

The same operator utilized the process to complete a Simpson sandstone well that was tight in the producing zone and was underlain by an aquifer. After perforating and stimulating the well with the GasGun, the well was hydraulically fractured at lower than normal pressure and no communication with the aquifer occurred.

A well in Russell County was stimulated with two 4’ GasGuns on top of a bridge plug at depth of 2385’. This Tarkio limestone well went from 0 to 5 barrels of oil per day with a considerable quantity of gas.

Other zones treated include the Mississippian, Pawnee, Fort Scott, Altamont, Bartlesville, Burgess, and Cherokee.

Experiences in other states indicate the process has applicability in limestone, sandstone or shale, and possibly coal.

Bottom Line

Stimulating Arbuckle producers presents special challenges. Apply too much horsepower and, even if just acidizing, one can easily find the ocean. Hydraulic fracturing produces a fracture that follows the path of least resistance, and, in the Arbuckle, experience shows that that path is vertically down into the water-bearing zone. Gas-generating, solid-propellant stimulation treatments using GasGunTM technology are proving to be one option that can produce fractures that stay in the zone treated and avoid finding the water.

For many formations, a GasGun treatment alone may be enough stimulation. In the Arbuckle, producers are using these treatments to produce a fracture network in the formation that provides a conduit for a subsequent acid treatment. The acid typically goes in on vacuum and increases oil production with little or no change in the percentage of water production. As of July 2003, 240 GasGun treatments have been conducted in Kansas including 70 in the Arbuckle dolomite. Economic success has been achieved in approximately 70% of these wells with a two- to three- fold increase in oil production normal. In a few cases, production increase has been 10 to 22 times the before-treatment rate.

History

Early in the history of the oil industry, many wells were stimulated with high explosives. But problems of wellbore damage, safety hazards and unpredictable results caused usage to decline. Extensive research on solid propellants that deflagrate rather than detonate has led to safe and more effective options.

Building on research conducted at Sandia National Laboratories in the early 1970s and a DOE Small Business Innovation Research grant, one such option, known as the GasGun™, became commercially available in July 1998.