An Expert System To Design and Evaluate Matrix Acidizing

Abstract

Summary An expert system called ACIDMAN has been developed to design matrix acid treatments which remove damage near the wellbore and increase production. Input data can range from unknown formation damage, for which the system designs a conservative treatment based on well history and geological probability, to cases with detailed formation information probability, to cases with detailed formation information available, in which case a very precise treatment is prescribed. The system will request that additional specific laboratory tests be performed, when needed, to aid in product selection. Basic input data requested includes: well type and history. formation damage mechanism, bottom hole temperature, reservoir pressure, formation permeability, lithology, porosity, interval pressure, formation permeability, lithology, porosity, interval size, and crude oil gravity. Output includes product selection, additives, treatment volumes and treatment technique. Phase I of the ACIDMAN expert system was delivered in beta test in March, 1990, and full implementation of all phases is planned during 1990. Introduction Formation damage occurring near the wellbore can be responsible for significant reductions in production (Figure 1). This formation damage has many forms and occurs in all phases of the life of a well. During the drilling of oil and gas wells, drilling muds invade the porous rock and later impede the production of fluids. It is also possible for drilling, completion production of fluids. It is also possible for drilling, completion and workover fluids to react with the formation fluids and cause a precipitate to form which constricts adjoining pores. Many formations contain internal coatings of clays which may react adversely with foreign fluids or migrate and block pore spaces during normal production.