A New Approach to Matrix Sandstone Acidizing Using a Single-Step HF System:A Niger Delta Case Study

摘要

The use of unique or modified HF acid systems for matrixrnacidizing within the Niger Delta and some other parts of thernworld is still the preferred method for effective stimulation ofrnsandstone reservoirs. The continued success of treatmentsrndone with modified HF systems in this area are due to itsrnability to mitigate the rapid spending of the active acid withrnclays and silicates; prevent matrix unconsolidation in the nearrnwellbore region and the subsequent precipitation of acidrnreaction by-products within specific well applications. Thisrnsuccess has brought about modifications to the acid systemrnand new applications for various well scenarios.rnThis paper discusses the successful application of a uniquernsandstone acidizing process that uses a single acid stage (nornpreflush or postflush is required) making multiple stagerntreatments much simpler while still achieving both economicrnand technical targets for the well. It covers the non-formationrnstimulation treatment of several wells using this single-steprnmethod and also describes a successful approach to improvingrnthe productivity of high water cut wells with severe finesdamagedrngravel packs by this system. Unique experiencesrnacquired during the field trials carried out within the NigerrnDelta using this system are evaluated. The results demonstraterna significant increase in incremental hydrocarbon productionrnfor normally high risk, low reward wells and remarkablernstimulation cost reduction via reduced chemical volumes, lessrnequipment requirements and shorter job times.rnAlso included are a thorough analysis of actual candidaternselection criteria, fluid chemistry, actual job design andrnoperational issues during execution of treatments. Keytechnical and economical performance indicators includingrnskin factors, production rates, specific productivity indices,rntreatment costs indicate that this system has certainly andrnsuccessfully increased the application envelope for unique HFrntreatments within sandstone reservoirs.