Assessment of Remediation Treatments in Underground Gas Storage Wells

摘要

The underground gas storage (UGS) industry uses more thanrn400 reservoirs and 15,000 wells to store and withdraw naturalrngas and is thus a significant contributor to gas supply in thernUnited States.1 Previous work indicates that many gas storagernwells show a loss of deliverability each year due to numerousrndamage mechanisms and it is estimated that tens of millions ofrndollars are spent each year to recover or replace thisrnlost deliverability.2rnPrior Gas Technology Institute (GTI) studies3,4 have beenrnaimed at qualitatively reviewing completion and deliverabilityrnenhancement techniques used in the storage industry,rnidentifying specific damage mechanisms present in storagernreservoirs, and establishing procedures for damage mechanismrnidentification. This paper presents key results of a major newrnstudy sponsored by the Gas Technology Institute (GTI) thatrnfocused on a comprehensive, quantitative assessment of therneffectiveness and longevity of the various stimulationrntreatments employed in the UGS industry.rnSpecifically, this paper summarizes the major results of thernmost comprehensive quantitative study conducted to date ofrnstimulation treatments employed in the UGS industry. Thernstudy involved seven operators and 23 reservoirs (14rncarbonate and 5 sandstone). Data were collected, entered intornthe database, and reviewed for 381 stimulations in 365 wells.rnDeliverability data were entered for 159 stimulations in 155rnwells (67 in carbonate reservoirs and 88 in sandstonernreservoirs) with sufficient data for inclusion in the study.rnThe most popular stimulation treatments currentlyrnemployed in the UGS industry are identified, the effectivenessrnand longevity of various treatment types are quantified andrncompared, and a new quantitative indicator designed torncapture the results of effectiveness and longevity calculationsrnin a single benchmark indicator is presented. In addition, thernfrequency and duration of cleanup effects for variousrntreatment types and the post-stimulation decline ratesrntypically observed for various treatments are alsornquantified and compared.rnThe implications of conclusions reached in the study,rnas they relate to future UGS R&D efforts, are alsorndiscussed, and specific areas of additional studyrnare recommended.