Evaluation and modeling of steam drive in diatomite under reservoir conditions

Abstract

There are large petroleum deposits in low permeability diatomaceous rocks. These oil deposits form a substantial part of original oil trapped in the San Joaquin Valley, California. Water flooding and steam drive with hydraulically fractured injectors and producers are possible ways of recovering oil from such deposits. Water flooding in diatomaceous rocks has not been widely effective, primarily due to the low mechanical strength of the rock. The brittle formation fractures easily and fracturing leads to injector/ producer linkage. Steam injection on the other hand shows better prospects of performance in these reservoirs. Since diatomite is primarily silica, steam injection into a diatomite reservoir could cause some changes in reservoir rock characteristics due to dissolution, transport and reprecipitation of silica. This study is aimed at modeling mathematically this dissolution process and predicting the dissolution and precipitation rates by developing a simulator code that predicts the physics of these processes. The simulator results will be compared with available experimental results. The mathematical model will then be updated to include the effect of this dissolution mechanism on the reservoir properties, such as permeability with duration of steam injection.