Building on the successful acidification of long cemented and perforated drains (~1000m) during the Central Area Development Phase of its AlKhalij Offshore field in Qatar (refer to SPE 54739), TotalFinaElf faced a new challenge for upcoming South-East Area Development Phase: how to boost productivity in extra-long drains applying previously proven principles, without going through unaffordable rig time? To snatch the maximum productivity (highest Productivity Index - PI) from horizontal drains in the over 2000m range, an homogeneous participation to production of the perforated intervals throughout the drain is crucial. In the matrix Mishrift carbonated horizon, a successful acid job is the key to meet the high production expectations that such long drains promised. The success of the stimulation relies on the necessity to open first the "toe" of the drain prior to bull heading - through a DST string - emulsified acid and water soluble balls sealers as the diverting agent. To deal with the here above requirements and in a "Rig time saving" approach, the "toe" and the remaining zones (the "heel") were successively perforated in one TCP run while ensuring pre-acidification of the lowermost perforations. The "double trigger" perforation technique was designed by the TotalFinaElf team in collaboration with the Service supplier. This technique consists in shooting the lower perforations in acid, squeeze this "in place" acid through annulus at a high pumping rate (to ensure a good Injectivity Index at the toe) and trigger the remaining perforations (remaining production intervals) in the same TCP run. Once TCP are pulled out of hole, a DST / acid string is run in hole and the main acid job performed in bull heading. The reservoir being hydrostatic to sub-hydrostatic, the well is kept on losses while running final completion. This paper documents the engineering approach and operational methodology implemented to reach high efficiency targets. Case histories are presented to illustrate these procedures, treatment designs and productivity results. Introduction The AlKhalij field. AlKhalij is an oil field located in the northern part of the Qatar sector of the Arabian Gulf. The Mishrift Reservoir. The reservoir is a stratigraphic trap. The oil bearing reservoir is part of the Mishrift formation within the Cenomanian limestones. The reservoir consists of a vertical succession of 6–9m (20–30ft) shallowing-up sequences. Each of them containing an alternance of poor permeability matricial layers and highly productive "drains" which can be correlated at the scale of the field. The total thickness of the Mishrift formation can reach 150m 500ft).

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Well Intervention Profitability Evaluation Project was aimed at applying a BP Corporate methodology (WETS, Wellwork Evaluation Tracking System, SPE 30649) to TotalFinaElf's Mature Fields.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Well Intervention Profitability Evaluation Project was aimed at applying a BP Corporate methodology (WETS, Wellwork Evaluation Tracking System, SPE 30649) to TotalFinaElf's Mature Fields.