A Systematic Approach for the Prevention and Treatment of Formation Damage Caused by Asphaltene Deposition

Abstract

Asphaltene plugging is a known cause of near-wellbore formation damage. Deposited asphaltenes can reduce effective hydrocarbon mobility by (1) blocking the pore throats; (2) adsorbing onto the rock, thereby altering the formation wettability from water-wet to oil-wet; and (3) increasing hydrocarbon viscosity by nucleating water-in-oil emulsions. Asphaltene flocculation and deposition can be avoided in some, but not all, cases. Some formation damage resulting from asphaltene plugging is permanent and hence must be prevented rather than treated. Prevention of asphaltene-induced formation damage should be started in the early stages of drilling and well completion, once the oil is known to be asphaltenic. This paper presents a systematic approach to successful diagnosis, prevention, and mitigation of asphaltene problems during recovery of asphaltenic oils. A mechanism of asphaltene flocculation and deposition is proposed and analyzed, and the previously defined concept of asphaltene deposition envelope is further refined. Diagnostic technology is presented that can test the compatibility of drilling and completion fluids with any asphaltenic oil. Important issues that need to be considered in the design of treatments for asphaltene removal are discussed. Finally, the paper presents a methodology for restoring unfavorable wettability changes caused by asphaltene deposition.

Permeability Damage Due to Asphaltene Deposition : Experimental and Modeling Aspects

“…It is defined as the fraction of the particles captured inside a flow tube parallel to the mean flow direction and with a cross section equal to the projected area of the collector (A c ). The capture efficiency is related to the commonly used filter coefficient l through: (2) where N stands for the number of collectors per unit volume.…”

“…Afterwards the asphaltene deposit zone can migrate to bottomhole and in the near wellbore formation as reservoir depletion proceeds. This is the long and well-known story of the Hassi Messaoud field [2,3,5].…”

“…Production problems related to asphaltene deposition generally appear first in the field in surface facilities, especially in separators, during the oil final depressurization step [1] and [2].…”

Correlations between SARA Fractions, Density, and RI to Investigate the Stability of Asphaltene

“…Many literatures [1][2][3] gave the description of asphaltene problems and remedies throughout the world. Although asphaltene precipitation is a worldwide problem, its main cause has not been completely under stood [4].…”

An Investigation into the Precipitation of Asphaltene from Maltenes Using Binary Mixtures of N-Paraffin

“…Deposition of asphaltene in oil wells, pumps, flowlines, pipelines and production facilities can reduce well productivity, damage pumps, restrict or plug flow line and pipelines and foul production handling facilities (15). Precipitated asphaltene may also build-up in the near well-bore, reservoir rock and clog the porous matrix of the reservoir during drilling and chemical treatment (8,11). Apart from causing the reservoir formation damage, asphaltene deposits could also result in reversal of the rock wettability which leads to a lower recovery factor (22).…”