Effective Well and Reservoir Evaluation Without the Need for Well Pressure History

摘要

This paper presents a practical and useful analysis techniquernfor effectively accomplishing a rigorous superposition-in-timern(convolution) analysis of the transient drawdown performancernof oil and gas wells that does not require that the flowingrnpressures (wellhead or bottom hole) be known for every flowrnrate data point in the production history. If at least onernflowing pressure point is available at any point in time duringrnthe production history of the well, a unique analysis of thernproduction data for the evaluation of the reservoir effectivernpermeability, well drainage area, and well parameters such asrnunfractured well radial flow steady-state skin effect, fracturedrnwell effective fracture half-length and average fracturernconductivity, or horizontal well effective length in the payrnzone may be obtained. Even if no flowing pressures arernavailable at all during the production history of the well,rnestimates of these well and reservoir parameters can still bernobtained with reasonable accuracy using the analysisrntechniques presented in this paper.rnThe general evaluation procedures presented in this paperrnare applicable for all well types, including flowing wells andrnwells with artificial lift systems (i.e., conventional beamrnpumping units and electrical submersible pumps (ESP)). Therntheoretical basis for a rate-transient analysis of the productionrnperformance of a vertically fractured well is presented in detailrnin this paper. Application of the proposed general analysisrnprocedure to other well types (unfractured vertical/slantedrnwells, horizontal wells, etc.) may also be found in a similarrnmanner as presented in this paper. The theoretical basis for arnpressure-transient based solution for a vertically fractured wellrnis also available in the references.rnIn the relatively short period of time that this new analysisrntechnique has been available, it has radically changed the wayrnthat engineers may now rigorously analyze the productionrnperformance of oil and gas wells to evaluate the well andrnreservoir properties from the well’s production performance,rnas well as greatly expanding the number and types of wellsrnthat can now be considered. The new analysis techniquesrnpresented in this paper therefore represent a step-change in thernpetroleum industry’s technical capabilities for the analysis ofrnthe production performance of oil and gas wells over thatrnwhich existed prior to this work.