Abstract

The expense of subsea well intervention often leads to insufficient reservoir information for accurately understanding reservoir connectivity, drainage, and flow assurance. For those wells requiring sand control, an additional constraint is that sandface sensors must be deployed on a separate completion run. The objective of a recent engineering development program was to create a new deployment system that directly addressed these constraints. Instead of individual gauges on mandrels, digital sensors were miniaturized and distributed along a single spoolable bridle. In addition, a novel inductive coupling mechanism was developed to pass power and data from the upper to the lower completion. In a recent subsea deployment in the SouthEast Asia, such a coupler was attached to the top of a sensor bridle and both deployed as part of an openhole gravelpack completion. Standard packers and gravel-pack service tools were used. The system became activated when a mating inductive coupler was landed as part of the upper completion. Surface indication of landing was provided by incorporating mechanical feedback into the lower assembly. With the coupler components in position, the tubing hanger was landed into the horizontal tree. Upon activation of the electrical penetrator, high-resolution temperature data were then immediately available across the length of the sandface, which was an industry first for a subsea producing well. No additional penetrations were required in the tree.

Development of this system required coordination from the operator because of the multiple vendors involved in the project. They supervised multiple qualification and system integration tests performed over the 2-yr development period to ensure ultimate success in the subsea deployment.

Field results showed that the mating inductive couplers provided high efficiency of power transmission so that industry standard power settings were sufficient to power a bridle with one sensor per joint of screen. The sandface data were available onshore during the cleanup phase, allowing the operator to monitor the cleanup in real time. Once the wells are brought online, the sandface data will further enhance the interpretation of flow allocation and reservoir drainage.

Introduction

Worldwide subsea activity is growing rapidly. Infield Energy Data Analysts (2008) forecast subsea expenditure to increase by 65% to USD 106 billion in 2008-2012 from a total of USD 68 billion during the period 2003-2007. Coupled with the increase in expenditure, they forecast a total of 2,408 subsea wells to be installed in the period 2008-2012, representing over 60% growth from the period 2003-2007 when 1,467 wells were installed. A large percentage of these subsea wells will require sand control and multistage completions.

Despite the growth in the number of wells, the expense of subsea well intervention often leads to insufficient reservoir information for accurately understanding reservoir connectivity, drainage, and flow assurance. For those wells requiring sand control, an additional constraint is that sandface sensors must be deployed on a separate completion run. Historically, subsea wells have lower total production compared with equivalent dry-tree installations, and most have less data (Selim, 2003). Hence, there was a crucial need for real-time sandface data, a robust mechanism to deploy sensors, a reliable connection technique between upper and lower completions, and a multidiscipline interpretation strategy to maximize the value of those sensors.

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