Unwanted water production is a major challenge in the horizontal wells in the Greater Burgan field in Kuwait. The long lateral sections and the presence of heterogeneity lead to uneven sweep of hydrocarbons. Greater Burgan has over 60 horizontal wells to date. Initially they produced dry oil and up to the expectation but soon the water cut increased in a number of wells and avoiding water break through became a major challenge. Burgan sandstone is a highly productive reservoir and the permeability variation is huge from less than a Darcy to a few Darcy. Thus, the horizontal wells have uneven flow profile and subsequent coning and cresting effects resulting in bypassed oil and poor recovery. To have a better down-hole water management in horizontal wells a number of options from chemical water shut-off and isolating the toe side using packers to use of straddle packers in the middle and heel side of the horizontal section were tried. However, the use of Inflow Control Device-ICD proved to be the best option to restrict and slow down and contain the water production by creating additional pressure drop and achieve better sweep efficiency. The first ICD completion in the Greater Burgan field and in KOC was implemented in a sidetrack well in 2007. To date the well is flowing with 45% water cut which is almost constant from the beginning for 7 years now. It resulted in a net gain of 2400BOPD from this well. This paper will describe this case history, how the system was designed, completed, and monitored, and the successful results achieved for over 7 years. This successful use of ICDs for water conformance lead to more applications in Kuwait and will give a good understanding for the future use in other areas.
The mature Great Burgan field comprises of more than 2000 wells to date, many of these wells utilize artificial lift in their production to maintain production targets. Tubing leaks and integrity issues pose major challenge to the artificial lift pump; these leaks eventually cause pumps temperatures to exceed the operating limit, trip and stop production. The waiting time for a workover rig is about 4 months, this converts to a significant loss of oil production in every well with tubing integrity issue. To reach and sustain the production target, rigless tubing repair is perceived as a viable quick solution to maintain production until workover rig becomes available.
For managing limited resources, short and medium horizontal sidetracks offer feasible options for non-conventional well work-over. Sidetracking into horizontal lateral is preferred over other options due to improved productivity. Many short-radius horizontal sidetrack wells with high Dog Leg Severity (DLS) have successfully been drilled and completed with Inflow Control Device (ICD) in carbonate reservoirs in the Middle East, however in case of sandstone reservoirs it poses a great challenge. This technology, which envisages short and medium radius horizontal sidetrack from existing well bore for optimal utilization of asset, was applied in a sick well from Greater Burgan field in Kuwait. A window was cut in existing 7″ casing and 6 1/2″ drain hole was drilled up to 6016′ MD. Initially this well was planned for sidetrack into main sand with maximum 35° DLS and feasibility study was done. But due to mechanical complications during work-over it was kicked off shallower, cutting shale above main sand, and the final well trajectory was maintained with maximum 23° DLS. The horizontal lateral was completed with 4 ½″ ICD and seven numbers of mechanically set open-hole packers for zonal isolation. The well completion with this technology with high DLS in a sandstone reservoir is probably the first time in the world. This paper will describe and present the case history of the application of this technology; the challenges faced during work-over, drilling of the drain hole with sand-shale contrast and the smooth running of completion assembly with high DLS. After work-over the well was put on production in May'08. As on date it is flowing with 45 -55% water cut which is almost constant since then, resulted in a net gain of 2400BOPD from this well. This successful sidetrack leads to more applications for exploiting heterogeneous reservoir in the Middle East Region.
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