Integrating Fresh Methodologies, Technologies and Atypical Procedures Leads to Outstanding Production Enhancement Results in a Mature Field

Abstract

The work completed was a comprehensive look into a mature gas field's intervention and production history to identify underachievement, redevelop the field management plan and implement successful remediation operations. The identification and characterization of skin was initially completed with physical inspection and slickline techniques. The decline curve analysis applied adapts to erratic declines from changing wellbore conditions, unreliable, or incomplete histories and provided accurate production forecasts. Pumping and coiled tubing techniques were used in the remediation work. In 2003 an Association was formed to manage a mature Romanian gas field producing since 1970. Production skin was evident and in 2010 the first well failed due to halite formation; consequently, liquid and solid sampling tools were deployed within suspect wellbores. The damage was characterized (halite, calcite and water blockage), novel decline curve analyses detected underperformance by integrating cumulative production histories. Twenty-two wells from one zone were initially assessed. All were damaged with some showing physical evidence of scale or salt, and a seven well pilot intervention campaign resulted in 38% peak incremental production. The outstanding results matched decline curve expectations and led to a full-field study, a campaign to intervene over half of the field based on that study, and possible expansion to all remaining wells in subsequent years. Technically, the innovative decline curve analysis proved crucial to discovering opportunities. Operationally, the optimized intervention procedures introduced were new to the basin and have been adopted by the Association partners in other assets. A major limit on ultimate recovery from depleted hydrocarbon reservoirs is declining well productivity. Salt formation, scale deposition, and water loading restrict flow: reducing production rates and increasing operating costs due to remedial interventions. Therefore, economical skin management is an essential tool for extending field life, increasing profitability, and improving recovery factors from aging assets. Impressive results led to a strategic shift in local field production management and the techniques are useful worldwide in similar fields.