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Hydrofracturing is one of the most commonly used methods of increasing production from low reservoir permeability reservoirs. Listening to the sounds of cracking rocks during hydrofracturing helps predict how fractures will propagate.
Drilling the first horizontal wells was slow and trouble-prone, costing several times a vertical or normally offset deviated well in the same reservoir. Improved management of drilling fluids centers on wellbore stability and cuttings removal.
This story tells how Danish operator Mærsk Olie and Gas AS snatched victory from the jaws of disaster. Mærsk Oil’s low-permeability North Sea chalks were yielding insufficient production to combat the slump in oil prices. The Solution: drill horizontal wells and then artificially fracture them. It had never been done before.
The recent flurry of horizontal drilling has enabled drillers to fine-tune their techniques, increasing speed, efficiency and control. We review high points of the lessons learned by this boom.
Interpreting logs from horizontal wells means accounting for influences that are negligible or absent in conventional wells—wellbore fluid separation, asymmetry of petrophysical properties around the wellbore, and variation of those properties along the wellbore length.
This is the last frontier of horizontal well technology. Drilling, logging, and MWD are technically in hand. But completing and stimulating horizontal wells has a way to go and is evolving rapidly. Selective isolation is the key, both for stimulation. We explore the difficulties and some current solutions.
Using an analytical model for the pressure response and flow regimes of the horizontal well in nonfractured formations, reservoir engineers recently interpreted pressure transient tests in an offshore India well.
Oilfield Review July 1990
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