A Comprehensive Expert System for Diagnosing and Assessing Formation Damage

Abstract

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractAn expert system capable of diagnosing the potential of formation damage caused by clay swelling, fines migration, inorganic scale deposition, and organic scale precipitation was developed and implemented. In this manuscript, we present results for the expert modules pertaining to asphaltene precipitation and asphaltic sludging. These modules estimate heuristically the potential for asphaltene precipitation, and for asphaltene sludge due to acidizing.Rules of thumb pertaining to asphaltene precipitation caused by solubility incompatibility between crude and solvent were collected. Membership functions to fuzzify these rules were constructed. The asphaltene module is capable of estimating the potential of asphaltene precipitation for a wide range of phase-behavior reservoir conditions, and for a much wider range of live and stock-tank crude compositions than what can normally be handled by a human expert. The acid sludge module makes its judgment based on factors such as acid strength, acid type, solvent preflush, iron control additives, Ferrous and Ferric ion concentrations, mutual solvent concentration, corrosion inhibitor type, and surfactant types used. A model has been formulated to predict the amount of asphaltene sludge that is likely to form as a consequence of crude-acid contact.A graphical user interface using various templates for data input and modules output has been built to make the expert system user friendly. The expert modules have been validated using a range of field data. This expert system gives the advantage of automating the diagnosis process pertaining to formation damage.

Disaggregation and discretization methods for formation damage estimation in oil and gas fields: an overview

“…Even so, it has the disadvantage of not considering the damage caused by geo-mechanical phenomena, being designed only for gas storage wells, and relying on excessive information and input data [44]. On the other hand, Garrouch et al [45] develop an expert system for the identification and quantification of formation damage by clay swelling, fines migration and deposition of organic and inorganic scales divided into two modules, one for clay swelling, deposition of inorganic and organic scales and another for quantification of the sludge formed by asphaltenes based on empirical, technical knowledge and results found in the literature. Specifically, asphaltene precipitation module can estimate the precipitation potential by the rule of thumbs criteria based on the type of crude oil and solvent used for a broad range of different types of reservoir fluids.…”

“…and low content of 7 C + fraction. Regarding the formation of sludge, the expert system finds that concentrations higher than 15% of HCl severely increase the tendency to form a slurry, in the same way, concentrations greater than 3% of hydrofluoric acid (HF) aggravate the damage by sludge formation [45].…”