Print this pageOvercoming Conventional Damage Mechanisms with Successful Underbalanced Drilling Techniques
DOANE, ROD D., D. BRANT BENNION, DAVID SHAW, ALAN GORDON and MIMI REICHENBACH
For years the oil industry has opted for the simplest and least expensive means to drill oil and gas plays. Overbalanced drilling (OBD) is still very successful in many applications, and remediation of damaged vertical wells can be relatively inexpensive and quick. However, with the need to exploit lower quality reservoirs and reduce the number of wells drilled, the trend has been towards more technically demanding drilling methods. Natural reservoir depletion and a desire to maximize wellbore penetration has increased the frequency of drilling of horizontal wells. Due to many of these wells being completed open hole, low drawdown pressures available for clean-up, extended exposure to mud filtrates in horizontal sections and prohibitive costs associated with mechanical stimulation techniques, the need to prevent damage from occurring at the outset is vital. Recently, it has been seen that underbalanced drilling (UBD) can reduce formation damage where conventional OBD technology would have detrimental effects. However, in certain situations, poorly designed and executed UBD programs may be more detrimental than OBD.
This paper discusses the mechanisms of damage that UBD techniques are designed to reduce and presents case studies which illustrate how laboratory testing has led to successful field applications.