Publications

Duri Oil Field contains heavy oil with 20 deg of API and 150 cp viscosity. A steam injection system has been applied to exploit the heavy oil in this field. Heterogeneous reservoirs in Duri Field cause the distribution of injected steam to be spread unevenly throughout the reservoirs. To improve the production performance of some wells that fail to respond to the steam injection, the Huff and Puff (H&P) method should be applied. In order to evaluate to what extent the steam injection affects the reservoirs, an estimation of heat radius from H&P was applied. Heat radius is the distance of heat from the steam injection that can affect the reservoir, and is measured from wellbore to the area affected by the steam heat. In this study, the heat radius will be estimated by a production response approximation at 30 H&P wells, whereas the heat radius was calculated based on the increase of oil volume on the surface. To find out whether the result of a heat radius calculation will still be within the correct range, a theoretical model approach (assuming that a calculated heat radius is affected by the amount of injected steam and several reservoir properties) has to be proposed. From the result of the heat radius calculation, H&P performance can be evaluated based on the productivity improvement of each well. From the heat radius calculation results based on production response, the conclusion was drawn that the heat radius was of about 20 to 40 ft. This result represents the actual condition of the field. In comparison to a theoretical model, it can be concluded that a heat radius achieving a production response approximation will still be within the same range as the calculation of a heat radius based on a theoretical model. This approximation can therefore be applied in the field. Based on the evaluation, a productivity improvement following Huff and Puff is obtained with the ratio in a range of 2.5 to 4.7 for each well.