No abstract

Much has been written about screening criteria and design methods for steamflooding. However, equally important is surveillance of existing projects. Fields undergoing expensive supplemental recovery processes cannot be installed and then left unattended. Careful monitoring of a steamflood is needed to ensure that the operator is producing the most oil for the least steam, or in other words, is maximizing the project's profitability. This paper describes one of the current surveillance programs for the Tulare formation steamflood in the South Belridge field, in Kern County, California. The progress of this steamflood is difficult to determine from volumetrics because of simultaneously flooding multiple sands with commingled injection and production wells. A primary tool was therefore needed to directly measure areal and vertical sweep efficiencies in order to optimize drainage and injection. This has been accomplished by the use of temperature observation wells in about one per every three five-acre patterns. The observers consist of wells converted to observation and newly drilled observation wells. Several logging techniques were evaluated to ensure accurate, economical and timely data. These observation wells are logged semiannually to determine the temperature of each of seven producing sands. This information is then used to construct computerized temperature isotherm maps for each sand over the entire field. These maps show which areas are being adequately heated and which are either too hot or not hot enough. Steam injection profiles and rates can then be adjusted accordingly using analytical heat balance calculations or temperature based injection guidelines from thermal reservoir simulations. The maps also show where additional steam injection wells or producers may be required.