Abstract
High-angle wells with longer and longer departures are being drilled at an ever-increasing pace on the North Slope of Alaska. This type well is used to penetrate new oil reservoirs and increase oil recovery in older fields. These older oil fields are under waterflood and gas injection to maintain reservoir pressure, and the wells are producing oil with high water cuts and high gas-to-oil ratios. This is a very complex environment to evaluate with production logs.
To assist in these complex interpretations, data from a new production logging tool string are being used to determine the production profile when a high-angle well is producing oil with high water cut and high gas-to-oil ratios. This compact tool string directly measures water holdup distribution around the wellbore, phase velocity data and provides X-Y caliper information. All measurements can be acquired as close as 16 in. (40 cm) to the bottom of the tool. Sensors to acquire data on pressure, temperature, inclination, gamma ray and casing collar locator are included in the tool string. The measurements can be made in either telemetry or memory modes. The memory mode eliminates the need for electric line when logging horizontal wells, or wells that have high surface flowing pressures.
Sensors for sigma/porosity and carbon oxygen measurements can be combined with this logging string (when run on wireline), so that the production profile and the reservoir behind the casing can be evaluated on a single trip. The combined data from the production profile and the formation are then used to determine how to produce the well and manage the reservoir for maximum oil production and recovery.
Production profiles from three wells are used to demonstrate the value of these direct measurements and how they were used in remedial work to increase oil production and reduce or eliminate unwanted gas and water production.
