As oil fields are being developed under difficult economical conditions, it becomes a matter of survival to be able to produce more oil with lower cost. In thermal recovery, one of the most important issues is the efficient use of steam injection. Temperature wells are used to measure the reservoir temperature. Geostatistical tools can be applied to these measurements to map reservoir temperature in a cross-section view or as a threedimensional volume for different time. This can help identify the steam-chest or hot-water region. When sand-zones are mapped and combined with the temperature map, cold regions in the sands can be located. The results can be used to estimate how much heat is in the reservoir and how much oil is remaining and where.

Geostatistical mapping has two advantages over conventional mapping. One is the geological concept of spatial continuity. Spatial continuity may be different in form and different for different direction and location. This offers flexibility and higher accuracy in the results. The other advantage is that geostatistical mapping can honor statistical distribution of the data. For example in the case of temperature, the lowest temperature and the highest temperature are usually limited and geostatistical mapping can honor these limits. Because temperature observation wells are usually far apart, geostatistical mapping can making full use of all information available to produce the best possible map.

Examples from the Kern River Field in California show how geostatistical mapping can be easily applied. A computer software on the PC is sufficient to do the job without additional cost. The results help the engineer optimize the thermal recovery operation.

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