The Use of Fiber-Optic Distributed Temperature Sensing and Remote Hydraulically Operated Interval Control Valves for the Management of Water Production in the Douglas Field

Abstract

Abstract Unwanted water production has long been one of the biggest problems that the oil and gas industry has had to address in efficiently producing hydrocarbons. This paper describes how fiber-optic-distributed temperature sensing (DTS) has been used in conjunction with remotely operated hydraulic interval control valves (ICVs) as an economical management tool for controlling water encroachment. Used with intelligent well technology, this method provides interventionless control and selectivity of producing intervals using surface-actuated hydraulic ICVs so that unwanted water production can be managed more effectively to maximize oil recovery. Distributed temperature measurements at one-meter intervals in the wellbore provide data that assists in the determinations of zonal contribution and the identification in the change of fluid properties or water ingress. This method was installed on the Douglas Platform in Liverpool Bay, United Kingdom. The completion was comprised of an ESP pump, hydraulic on/off disconnect, retrievable packers with hydraulic feed throughs and hydraulic ICVs. An optical fiber that acquires continuous distributed temperature data is installed into one of the hydraulic control lines that operate the hydraulic ICVs. Opto-electronic instrumentation on the platform allows distributed temperature data to be transmitted in real-time to a shore-based asset team. The combination of fiber optics and hydraulic interval control valves provides a number of benefits:The number of penetrations through tubing hangers and packers are reduced if requiredThe fiber optic sensor is capable of gathering real-time logging data from multiple intervals without interventionThe ICVs provide interventionless zonal controlThe disconnect system facilitates ESP workover and recompletion. Introduction Field Background. The Douglas Field is a shallow low-pressure, under-saturated oil reservoir situated offshore in the Liverpool Bay area of the East Irish Sea on the west of Great Britain. The Triassic sandstone reservoir lies at depths between approximately 2,250- and 3,000-ft. MD. The reservoir is made up of a number of geological facies; i.e., aeolian dune, aeolian sandstone, sandy sabka, fluvial channel, partial fluvial and mudstone and consists of a number of distinct zones with varying reservoir qualities. These are shown in Table 1. The wells are drilled from a central wellhead tower and because of the shallow nature of the reservoir, the wells are highly deviated as shown in the deviation survey in Fig. 1. It can be seen that the wells extend up to approximately 12000 ft. The oil producers are all completed with ESP's that provide the necessary artificial lift to obtain economic production rates. There are other features of the completion, notably the formation saver valve (FSV), which allows the ESP to be worked over without excessive fluid loss to the formation.