Reservoir Conformance Control(RCC)methods may significantly improve IOR/EOR technologiesthrough reduced water production and profile correction.In the past decades,polymer gel methods werepredominantly applied with these goals.However,recently the silicates in oilfields and microemulsionsin gas fields are highly appreciated by the operators due to their outstanding features and environmentalfriendly character.That fact is well demonstrated by more than 140 jobs carried out in Hungary,Serbia,and Oman.Although,the statistical data of these projects are attractive(75% technical and 55% economicsuccess),probably much higher profitability could be attained if not underdosing but optimal amountof chemicals were applied to avoid deterioration of well performance(well killing in extreme case).Unfortunately,overdosing might be often realistic because of limited information on wells to be treated.Consequently,developing any water shutoff methods must comprise techniques,which must be used torehabilitate the productivity,permeability,injectivity.That question is practically not discussed in theliterature.Concerning the barrier formation kinetics and processes,the different methods can be subdivided intotwo groups:reversible and irreversible gelation techniques.The in-situ formation of polymer gels,whateverits types are,represent the latter one,viz.detrimental effect of chemical overdosing is hard to control evenby strong oxidative agents.In contrast,the silicate methods using both external and internal pH control,the hard gel formed after placement,the formation damage can be mitigated by injection of strong alkalinesolutions.Similarly,the microemulsion treatment based on phase inversion under reservoir conditions,thebarrier(with 5000-10000 cP viscosity)can be disintegrated with post-injection of special organic solvents.These phenomena and processes are addressed with bulk phase studies and flow tests in sandstone cores.Independent parameters of these tests were the type of chemicals,concentration,temperature,and reactiontime.The experimental findings clearly demonstrate that the silicate lamps can be completely dissolvedin bulk phase,and the detrimental effect in porous cores can be mitigated by 60-70% improvement ofpermeability in case of overdosing chemical treatments.Similarly,even more favorable data characterizedthe disintegration of microemulsion barriers using bulk and flow tests.Special advantages of these mitigation procedure are that environmentally friendly chemicals are used for alleviation of the unintendedformation damage.The experimental results proved that the different silicate and microemulsion methods are based onreversible barrier formation.Recognizing that fact,the design of treatment offers more engineering freedomto use not minimum,but optimum chemical load in treatments without jeopardizing the undersignedformation damage.Nevertheless,this happens,the operator has appropriate technology to eliminate thedetrimental effects.
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