Abstract:
The Kenkyak sub-salt oilfield in Kazakhstan is characterized by deep buried depth of oil reservoirs and complex geological conditions.And especially in the fourth casing section (Ø149.2 mm), high-density drilling fluid is used.As a result, the exploration and development difficulty is increased and great challenge is bought to the coring operation in this block.In order to overcome the difficulties of complex geological conditions and high-density drilling fluid, the stratigraphic laws of sub-salt oil reservoirs were analyzed, and then based on the characteristics of the drilling technologies applied in this block, a high-strength, small-diameter coring tool was developed.In this coring tool, the stability of inner barrel is improved by using the sealed bearing and the aluminum inner barrel with centralizer, and the coring operation efficiency and the core recovery are increased by using the new type coring bit, the basket type core catcher and the flapper float valve.Field application results indicate that by virtue of this new coring technology, the drilling and coring technical difficulties in this block are solved and the coring results are improved remarkably.Obviously, this technology is worth popularizing and applying further.