This paper was presented at the SPE/DOE Fourth Symposium on Enhanced Oil Recovery held in Tulsa, OK, April 15-18, 1984. The material is subject to correction by the author. Permission to copy is restricted to an abstract of not more than 300 words. Write SPE, 6200 North Central Expressway, Drawer 64706, Dallas, Texas 75206 USA. Telex 730989 SPEDAL. Al:ISTRACTBeyond a critical rate of flow in cores the viscoelasticity of polyacrylamide solutions is reflected by shear thickening behaviour. Practical information is provided on the critical flow rate and magnitude of shear thickening and their dependency on core permeability, temperature, molecular weight and concentration of commercial polymers. To describe the onset of shear thickening, critical Deborah numbers were calculated using fluid relaxation times obtained by oscillation rheometry. Using three core-flow parameters, viz. the critical flow rate and two powerlaw exponents, the viscoelastic effects are quantified.

kBSTRACT INTRODUCTION Laboratory research on the steam-foam process as The effectiveness of steam injection into a heavy a means of reducing steam mobility in steam-injection oil reservoir can be increased by improving the aerial projects indicates that steam-foam formulations, which and vertical distribution of the steam. llsiscan be are effective in pilot tests at low steam accomplished by reducing the steam mobility; one temperatures, are not necessarily effective at method of doing this is to inject steam with foaming temperatures over 200~. agents' as currently appliad in various US projects.However, long-chain alkylaryl sulphonates exhibit In a steam-soak well the development of a steam an excellent capability for reducing steam mobility at tongue, reaching deep into a reservoir, is beneficial elevated temperature; furthermore, this class of for the activation of oil production mechanisms. surfactants is thermally stable. The performance of However, reservoirs often consist of several permeable steam foam with these surfactants has been studied in sands separated by ehale breaks. If steam is injected core-flow experiments at steam-injection tefrperatures into such a reservoir, steam injection wL1l often be representative of steam operations in the Tia Juana restricted to the top sand. 'lW.ssituation can be field, Venezuela and as a function of the following improved by reducing the steam mobility with foam, parameters: surfactant molecular weight and which will cause the steam-injection pressure to concentration, the presence of an electrolyte, the increase and the steam to be diverted to lower sands. addition of small amounts of a non-condensable gas, and steam quality. me surfactant molecular weight and Most of the experience gained so far with steam concentration appear to be the main parameters for foam in the USA is related to shallcw reservoirs where reducing steam mobility.pressures and temperatures are relatively low. However, in other areas, for example, the Tia Juana The laboratory research was followed by a pilot field in Venezuela, much higher pressures an3 Lest, operated by Flaraven,in the Tia 3aana field, in corresponding temperatures are used. Furthermore, in attempt to improve the injection profile in steam-steam qualities are different, varying from 50 to 60% 3oak wells.in the California fields, and from 80 to 90% in the L%e results obtained so far indicate the feasibility Tia Juana field. >f: . reducing the effective steam permeability, This paper deals with the joint research efforts plugging the most depleted layers, of Shell and Maraven on the mobility-reducing . diverting the injected steam to non-producing sands, capability of foaming agents for the high temperatures . enhancing oil production.prevailing in the Tia JUana field (21 bar, Zls"c). 3ased on the test results and operational conditions, the possibility of optirrdsingsteam-soak operations The laboratory work involved selecting a under Solivar coast conditions has been established. candidate surfactant and evaluating the steam...