Establishing Inflow Performance Relationship (IPR) for Gas Condensate Wells

摘要

A new simple method of establishing Inflow PerformanceRelationship for gas condensate wells is proposed. Theproposed method uses transient pressure test data to estimateeffective permeability as function of pressure and then uses itto convert production BHFP data into pseudopressure toestablish well performance. Requirement of relativepermeability as function of saturation thus has beencompletely eliminated. Effective permeability of either phasecan be used to predict the production of second phase. Ascheme has also been devised to estimate the effectivepermeability using well testing mathematical models availablein literature.Also mathematical models of well deliverability loss dueto condensate deposition when dew point pressure is reached,and deliverability gain due to condensate mobility when P* isreached have been developed. Pseudopressure curves for bothoil and gas phase have been developed for quick conversion ofpressure data into pseudopressure. Relative permeabilitycurves if available can also be used, however, the knowledgeof saturation has to be known at all the stages of the depletionto be able to use them.Gas condensate reservoirs are primarily gas reservoirs. Asthe pressure declines with depletion, reservoir conditions ofpressure may go below dew point and liquid begins to buildup.Such reservoirs may go under liquid buildup without showingany trace of liquid production. Sudden well deliverability lossand very high skin factor estimates from pressure tests arestrong indicators of liquid buildup. PVT characteristics likephase diagram help identify the problem too. As the criticalconditions are reached such reservoirs become two phasein nature.Finally, a field example is analyzed to show the use ofnew method developed and a step-by-step procedure is usedto establish the well performance. Small operators,Independents, will benefit from this method at the most, sincedata acquisition like relative permeability curves require thelaboratory experiments on cores, an expensive procedure.