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Abstract

Over the past few years, a new multi-stage, multi-jet fracturing technology has improved the acid fracturing of the Wabamun formation located in south central Alberta.

The Crossfield member of the formation, found in the Swallwell field, has a large original oil and gas reservoir with low recovery factors to date of 2.4% for oil and 5.2% for natural gas.  A 1% increase in recovery factors would yield an additional 875,000 bbls and 851,000 mcf of gas.  

Use of multiple mechanical isolation points in the new technology has demonstrated average initial production increases of 77 to 102% and final production increases of 12 to 28% compared to historical wells.  The micro to very fine crystalline dolomite of the Crossfield member has average permeability ranges from 0.1 and 0.3 mD; therefore, acid stimulation is required in order to economically extract the resource.

This paper will discuss the planning and design processes that led to the implementation of the multi-stage, multi-jet technology.  It will outline the lessons learned during deployment of the completion, and will highlight the stimulation treatment execution and post-stimulation results. The text will detail examples from the case studies and will outline the benefits of this technology.

Introduction

In 1998 and 1999 horizontal drilling was initiated in the Wabamun formation within the Irricana field in south central Alberta.  Initial two month production values were, on average, 3875 BOE/m (barrel of oil equivalent per month; gas is included as per SPE conversion factors).  Over the next nine years, monthly production decreased to an average of 492 BOE/m providing the impetus to develop a plan for enhancing production with acid fracture stimulation methods. 

This section will introduce the reservoir characteristics and the completions tool components.  The following sections will provide a completions history and then outline case histories of three progressive completions methods attempted with the associated production results culminating in a final completions design now used by the operator for all wells in the Swallwell field.