TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Belanak field in the Natuna Sea of Indonesia is located 253 miles northeast of Singapore in 300' water depth ( Figure 1). The field development consists of two wellhead platforms, with 16 wells drilled from platform A, and 18 wells planned for platform B. Due to the remote location of the development, and the space and storage limitations inherent to a platform rig, logistics and equipment design were the major front-end engineering issues of the drilling project. The early concerted effort of the operator and contractors to front-end planning and design led to the realization of several drilling records and first-time accomplishments in the Natuna Sea. Figure 1: Area map of the Belanak field.

The objective of this paper is to outline and discuss the learnings which improved the drilling and completion process of horizontal wells in depleted Carboniferous reservoirs. The learnings were derived from three replacement wells drilled and completed on the Conoco (U.K.) Limited operated Murdoch Field, which is a mature development in the Quadrant 44 area of the United Kingdom Southern North Sea (UK SNS) (refer to Figure 1). The replacement wells were drilled in an effort to restore production volumes that were lost when two of the original wells mechanically failed due to downhole conditions. The paper will summarise the following: Failure analysis of the original wellsBasis of design for the three replacement wells including sand control issues of depleted reservoirs Operational summaries for three wells will be thoroughly discussed. The learnings gained from the failure of the first well was applied to the planning and implementation process of the two remaining wells. The wells were successfully drilled and completed. The initial production rates of these two wells were equal to or greater than the original development wells even though the reservoir pressures were significantly reduced.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn October 2003, development drilling of the ConocoPhillips Indonesia Inc.Ltd operated Belanak Field commenced when the platform rig was rigged up over a previously installed twenty-four slot platform. Drilling commenced with the objective of drilling and completing ten slant directional wells and six horizontal wells.The objective of the Field development was to have high production rates available when the FPSO facilities arrived approximately twelve months later. Since the wells had to be pre-drilled before first production,it made sense to utilize a full batch drilling concept in order to minimize costs.The 13-3/8" surface casing strings were successfully batch set on all sixteen wells. This section was completed fifteen days ahead of budget time and set several world record penetration rates for a 16" tricone bits.The 9-7/8" hole/7-5/8" casing sections were batch set in ten wells. Most well objectives were met and the performance was exceptional in some wells, but, this section was plagued by surface and downhole equipment failures.The 12-1/4" hole/9-5/8" casing sections were batch set in six wells. All well objectives were met including landing all wells in the reservoir at 90 o . Time to complete this section was longer than expected due to inconsistent BHA response.The 8-1/2" horizontal hole sections were then drilled and completed with a 3,500 ft average hole length for the same six wells.This paper will focus on the drilling operations and discuss the performance and problems encountered. The Belanak drilling team was committed to continuous improvement by capturing data and immediately implementing the learning's. This commitment to maximize the learning curve resulted in minimizing cost and a successful intensive batch drilling operation.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Belanak field in the Natuna Sea of Indonesia is located 253 miles northeast of Singapore in 300' water depth ( Figure 1). The field development consists of two wellhead platforms, with 16 wells drilled from platform A, and 18 wells planned for platform B. Due to the remote location of the development, and the space and storage limitations inherent to a platform rig, logistics and equipment design were the major front-end engineering issues of the drilling project. The early concerted effort of the operator and contractors to front-end planning and design led to the realization of several drilling records and first-time accomplishments in the Natuna Sea. Figure 1: Area map of the Belanak field.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn October 2003, development drilling of the ConocoPhillips Indonesia Inc.Ltd operated Belanak Field commenced when the platform rig was rigged up over a previously installed twenty-four slot platform. Drilling commenced with the objective of drilling and completing ten slant directional wells and six horizontal wells.The objective of the Field development was to have high production rates available when the FPSO facilities arrived approximately twelve months later. Since the wells had to be pre-drilled before first production,it made sense to utilize a full batch drilling concept in order to minimize costs.The 13-3/8" surface casing strings were successfully batch set on all sixteen wells. This section was completed fifteen days ahead of budget time and set several world record penetration rates for a 16" tricone bits.The 9-7/8" hole/7-5/8" casing sections were batch set in ten wells. Most well objectives were met and the performance was exceptional in some wells, but, this section was plagued by surface and downhole equipment failures.The 12-1/4" hole/9-5/8" casing sections were batch set in six wells. All well objectives were met including landing all wells in the reservoir at 90 o . Time to complete this section was longer than expected due to inconsistent BHA response.The 8-1/2" horizontal hole sections were then drilled and completed with a 3,500 ft average hole length for the same six wells.This paper will focus on the drilling operations and discuss the performance and problems encountered. The Belanak drilling team was committed to continuous improvement by capturing data and immediately implementing the learning's. This commitment to maximize the learning curve resulted in minimizing cost and a successful intensive batch drilling operation.