Formation Damage and Matrix Acidizing Fundamentals

Formation Damage and Matrix Acidizing Fundamentals

This skill module addresses the complex oilfield phenomena that studies and attempts to resolve production loss or less than expected production rate following initial completion or any well workover or intervention activity. Formation damage is a term often used to describe the cause of production loss; its use is commonly misunderstood or misused as many factors and circumstances may be the cause of reduced rate. The set of circumstances referred to as “True” Formation Damage is described in detail; production loss caused by these circumstances may often be remediated as long as causes are properly defined and appropriate remedial steps are taken. Other causes of production shortfall, also grouped into the formation damage term to describe lost production, are identified in the module along with recommended remedial steps to address them. Use of the reservoir engineering term “skin” is explained and quantified in the module. Production loss remediation due to “True Formation Damage” using principles of matrix acidizing and surfactant chemistry are presented in detail. The complex reactions that take place using a Hydrofluoric acid / Hydrochloric acid on sandstones (referred to as “Mud Acid”) and the Hydrochloric acid reaction on limestones to remove production loss factors are explained. Fracture acidizing of limestones is explained and examples illustrated. Matrix acidizing operational considerations of corrosion inhibition, acid additive selection, iron control, acid diversion, and related important topics are addressed and explained. Several practical exercises are worked to illustrate key module principles.