Abstract

Atlantic Richfield Indonesia Incorporated commenced studies into horizontal drilling in mid 1984 when the BIMA Field development was proposed. High mobility ratios resulting from the nature of the crude together with the close proximity to gas and water contacts in the Batu Raja limestone made this an ideal candidate for high angle or horizontal drainhole drilling.

In January, 1986, a high angle hole was successfully drilled in the BIMA Field using conventional techniques to turn the hole in excess of 85° in 1400 feet TVD. This angle was chosen rather than drilling a horizontal hole because of the need to drain two distinct porous layers in the productive Batu Raja formation.

The 85° hole reached a total drilled depth of 4500 feet in 15 days. A second well confirmed that high angle drilling under BIMA conditions was a practical approach for development of the BIMA Field. The total well cost for drilling and completion was similar to that for conventionally drilled 45°-60° wells. Furthermore, it was concluded that additional savings in the total number of required development wells would result because of the extended drainage of the high angle boreholes.

Evaluation of the first well involved new and interesting techniques. These involved the use of drill pipe conveyed logging tools, unusual approaches to log response (bed identification, deep tool response near overlaying beds, etc.) and pressure build-up analysis over long sections.

Initial test results indicated a PI improvement over normally angled wells with the attendant benefits of reduced gas and water coning due to minimized drawdown. These results will be further examined early in 1987 when the wells can be tested under extended test conditions after the field is onstream.