New Vision: IC TAML5 Wells on Caspian Offshore. Reasons, Implementation and Results
Authors: Eliseev D. , Golenkin M. , Senkov A. , Latypov A. , Bulygin I. , Ruzhnikov A. , Buyanov M. , Kashlev A. 
Published: October 2016

In 2015, LUKOIL-Nizhnevolzhskneft developed two intelligent multilateral (TAML 5) wells in the Korchagina field in the Caspian Sea—a first for LUKOIL and Schlumberger, the company's service provider. The development of offshore fields is difficult, requiring nonstandard procedures and solutions, including the use of new technologies to construct multilateral wells. This paper describes the approach to designing these wells with TAML 5 intelligent completions in conditions where there is a high risk of gas and water breakthrough. The main objectives for this type of completion were extending the production period before catastrophic gas breakthrough, increasing the drainage area by drilling several drains, and, as a result, increasing total oil recovery.

The formation of Korchagina field is an oil rim with height of 20 m located between the massive (up to 90 m) gas cap and bottom edge water. In the majority of wells (usually extended-reach drilling (ERD) wells), the first three months of production see gas breakthrough, drops in oil production, and the gas/oil ratio (GOR) reaching values up to 5,000 m3/m3. To reduce the rate of gas breakthrough and delay water breakthrough, a new well design was proposed featuring the following technologies: dual-lateral production wells with a TAML 5 junction; active monitoring of inflows from each lateral in an interval of the junction by using multiposition valves hydraulically controlled from the surface; pressure and temperature sensor system that enables real-time tracking of the formation conditions in the drainage area of the laterals, estimates flow rate from each lateral, and interprets the obtained data to determine reservoir parameters.

The first TAML 5 intelligent well had a very stable flow regime with a flow rate of more than 400 tons of oil per day. GOR and water cut showed a better dynamic when compared to offset wells in the field, where gas and water breakthrough was observed. One of the main reasons for this was the ability to control drawdown in each of the laterals by using multiposition valves installed in the pressure-tight junction. When compared to the standard monobore well drainage area, boundaries have been considerably extended. At the same time, production was achieved with much lower drawdowns than for wells with a single lateral, while maintaining the same flow rate. As a result of smaller reservoir and tubing pressure differences, the speed of the water and gas vertical movement significantly slowed down, even with the proximity of gas-oil contact (GOC) and oil-water contact (OWC) to the wellbores.

The second TAML 5 well was sidetracked from the existing well. Prior to sidetracking, the well was producing with high GOR (more than 2,000 m3/m3) and low flow rate. After the sidetrack was drilled and completed, total GOR decreased by 75% while the production rate increased more than 3 times. The main reason for such a positive change was the increase in coverage ratio, as well as the redistribution of the drawdown between and along the laterals.

In both wells, the intelligent completion enabled real-time drawdown redistribution to respond to changes in well production during the life of the well. The use of a pressure-tight TAML 5 junction is relevant for any field with an active gas cap.

This manuscript provides the details of the development, justification, and field-testing of this new approach for the development of offshore fields by using multilateral intelligent wells and a pressure-tight TAML 5 junction to substantiate the advantages and benefits of this technology.