Leif Hinderaker, SPE, Norwegian Petroleum Directorate, Rolf H. Utseth, SPE, Statoil, Odd Steve Hustad and Idar Akervoll, SPE, IKU Petroleum Research, Mariann Dalland, Bjorn Arne Kvanvik, Tor Austad, and John Eirik Paulsen, SPE, RF-Rogaland Research. Abstract RUTH (1992-1995) was a four year Norwegian research program on improved oil recovery funded by Norwegian authorities and 18 participating oil companies. This paper describes how the program was organized and highlights the main results. Research was performed within six main themes: Gas flooding, combined gas-water injection including WAG, foam, polymer-gels, surfactant flooding, and microbial method. Applications in Norwegian fields are discussed with special focus on field pilot tests. The program contributed to establish a pilot-activity on three new methods, WAG, foam, and polymer-gel, on the Norwegian continental shelf. Introduction An important goal for Norwegian petroleum policy has been to secure the best possible exploitation of the petroleum resources. The initiation and implementation of IOR R&D programs have been an essential part of the strategy to reach this goal. Several major Norwegian IOR programs have therefore been initiated since the nineteen eighties. These are listed on Table 1. The Joint Chalk Research program, dedicated to improving hydrocarbon production from Norwegian and Danish chalk fields, was launched in 1982 on the initiative of Norwegian and Danish authorities. The state sponsored SPOR program, which was carried out during 1985 through 1991, focused on IOR and EOR methods, and had as its main goal to build a national Norwegian IOR expertise. Two follow-up programs were initiated after SPOR: The PROFIT program, concentrating on "Reservoir Characterization" and "Near Well Flow", and RUTH. PROFIT was a collaborative program between 13 oil companies and the Norwegian Petroleum Directorate (NPD). About 50 million USD have been invested in these programs, including RUTH. RUTH (Reservoir Utilization through advanced Technological Help) was a cooperative IOR effort conducted by the Research Council of Norway, the Norwegian Petroleum Directorate, Norwegian research organizations, and 18 oil companies. The total program budget was 106 million NOK. The Research Council of Norway funded 55 million NOK, and 51 million NOK was funded by the participating oil companies (1 USD is about 6.50 NOK). The program lasted 4 years (1992-1995), and a total of 32 projects were performed. RUTH aimed at following tip the research topics included in the SPOR program which were not conducted by other programs, and to include new subjects of strategic importance. The main objectives were:–Contribute to increase oil recovery from sandstone and chalk reservoirs on the Norwegian continental shelf by 300 million Sm3.–Meet the authorities' specific and long-term requirements for research on advanced oil recovery.–Help Norwegian research groups to further develop an internationally recognized expertise that can be of use to the oil companies. Additional objectives were to concentrate on applied research that is related to advanced recovery methods and to help qualify advanced technology by means of field tests. Of the three main objectives, we believe the first objective will be reached through the use of the developed technologies, and that the other two objectives have been met. P. 251

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This paper describes a simulation model for gel placement. The model is a modified UTCHEM simulation model. Experimental data including retention, gelation strength and gelation rate are matched with the model. It has been stressed that the same set of input data are used in the simulations of the different experiments. The retention of the crosslinker can be crucial and is deseribed by the dissolution of carbonate minerals in the reservoir. In shut-in treatments, gelation strength is found to increase as the permeability increases. Gelation or aggregation is also described during a continuos injection.Reservoir simulators exist that can handle gel simulations as SCORP103*4, STARS5, BOAST6, BPOPE7, UTCHEM.8 Some models have also been proposed that are mainly made for gel simulations.9~10The model presented in this paper differs from the earlier proposed models in several manners. The most important difference is however the link between the crosslinkerretention/precipitation-pH and mineral dissolution from the reservoirrock. SIMULATION MODELThe gelation model is implemented in an in-house modified model of UTCHEM. The extended UTCHEM (in house version) is a three dimensional, multiphase, multicomponent IMPES code. In-house modifications and additions include: improved surfactant phase behaviour description (asymmetric binodal curves, microemulsion viscosity, effects of temperature and GOR, multisurfactant systems and a new kinetic adsorption routine allowing for competitive adsorption if more surfactants are present)