The Relative Importance of Wellbore Pressure Drop and Formation Damage inHorizontal Wells

摘要

Numerous studies have examined the roles of wellborernpressure drop and near wellbore formation damage on thernproduction performance of horizontal wells. These studiesrnhave identified particular conditions for which these effectsrnare important, but no quantitative general guidelines have beenrndeveloped. In this paper, we present simple, analyticalrnexpressions that can be used to determine the relative effectsrnof wellbore pressure drop and formation damage on horizontalrnwell inflow. The equations developed are used to show howrnhorizontal wells or laterals can be designed so that neither ofrnthese effects causes significant flow restrictions.rnThe relative importance of the pressure drop in a horizontalrnwellbore is shown to be a simple function of tworndimensionless numbers, the Reynold’s Number for the flow inrnthe wellbore, and a new dimensionless number called thernHorizontal Well Number. With this relationship, we illustraternhow the wellbore diameter and length can be designed torninsure that the wellbore pressure drop is not restrictingrnproduction.rnWe also illustrate in this paper a technique for identifyingrnthe most critical part of the well flow system (far-fieldrnreservoir flow, near well convergent flow, or flow through therncompletion) from the relative sizes of different terms in therninflow equations. This analysis method shows that thernimportance of formation damage and the efficiency of wellrnstimulation depend on formation thickness, well length, andrnreservoir extent in the horizontal plane. Guidelines arernpresented to show how much damage can be tolerated whilernstill maintaining productivity within a prescribed fraction ofrnthe undamaged productivity.