TY - THES

T1 - Managed Pressure Drilling (MPD) as tool to optimize formation damage

AU - Fischbacher, Erwin

PY - 2005/10/18

Y1 - 2005/10/18

N2 - A main goal in well engineering is to drill and complete a well for maximum recovery. During traditional overbalanced drilling operation mud operates as primary barrier against formation pressure and generates formation damage. If formation - and pore pressure are close, or formation pressure due to production is low, conventional drilling methods are inapplicable. Managed pressure drilling (MPD) can be accomplished in different technical implementations to control a specific pressure exposure against the formation. In this work, techniques convertible on “floating rigs” are examined. Formation damage is also dependent on the degree of overbalance pressure during drilling operation. A high degreeof overbalance pressure causes increased filtration rates and particle migration effects. Semi- and fully dynamic core tests are performed to evaluate the influence of pressure on formation damage. A model is presented whichallows the scaling of lab results to reservoir conditions. The result of this work shows the distribution of filtrate invasion depth along the wellbore. Based on core tests it is possible to calculate the local skin along a well. The local skin is influenced by the return permeability and filtration rates. The local formation damage is calculated for a simulated drilling process based on filtration loss, permeability impairment caused by the internal filter cake and migrating fines.

AB - A main goal in well engineering is to drill and complete a well for maximum recovery. During traditional overbalanced drilling operation mud operates as primary barrier against formation pressure and generates formation damage. If formation - and pore pressure are close, or formation pressure due to production is low, conventional drilling methods are inapplicable. Managed pressure drilling (MPD) can be accomplished in different technical implementations to control a specific pressure exposure against the formation. In this work, techniques convertible on “floating rigs” are examined. Formation damage is also dependent on the degree of overbalance pressure during drilling operation. A high degreeof overbalance pressure causes increased filtration rates and particle migration effects. Semi- and fully dynamic core tests are performed to evaluate the influence of pressure on formation damage. A model is presented whichallows the scaling of lab results to reservoir conditions. The result of this work shows the distribution of filtrate invasion depth along the wellbore. Based on core tests it is possible to calculate the local skin along a well. The local skin is influenced by the return permeability and filtration rates. The local formation damage is calculated for a simulated drilling process based on filtration loss, permeability impairment caused by the internal filter cake and migrating fines.

KW - Managed Pressure Drilling / Kern-Tests / Filter-Kuchen-Kompressibilitaet / Feststoff-Migration / Filtrations-Tiefe / Permeabilitätsschädigung

KW - Managed Pressure Drilling / core testing / mud cake compressibility / particle migration / filtration depth / permeability impairment

M3 - Master's Thesis (University Course)

ER -