Abstract

Effective sand control and high well productivity throughout the life of the well have been defined as success criteria for the use of Stand Alone Screen as sand control strategy. This paper describes the strategy to meet these success criteria and illustrates the experience in Hydro Oil & Energy to date.

A recommended practice for the selection of sand control has been established based on a comprehensive screen selection and fluid qualification process. The method includes testing and ranking of different screen designs based on sand retention and plugging properties for selected samples of reservoir sand. The screen design with the overall best performance is recommended for field application.

In addition, requirements for drilling and completion fluids have been defined. Control of particle size and particle amount in the completion fluid has been identified as the most important criteria.

Stand Alone Screen as sand control strategy have been successfully utilized for approximately 230 completions based on the presented methodology. For several of these wells, the established selection criteria published in the literature, recommended other sand control techniques to that used, e.g. open hole gravel pack. Based on Hydro Oil & Energy 's field experience the common practice for sand control selection applied within the industry today might be too cautious. It is concluded that Stand Alone Screen as completion method can have wider application than recognized so far.

Introduction

Hydro Oil & Energy operates 13 oil and gas installations in the Norwegian sector of the North Sea. Drilling and completion of long horizontal (typical 2000 m) and multilateral wells have been an important part of the development of these fields.

The reservoir rock is sandstone and the degree of consolidation varies. For most of the wells active down hole sand control is required. Due to the length of the horizontal section and the complexity of these wells Stand Alone Screen, SAS, has been the preferred completion method based on technical and cost efficiency.

Due to the limitation and the vagueness of the criteria for screen selection for SAS completions, an in-house testing method was developed during mid 90's 1. The method has been further refined, and based on this together with field experience from more than 10 years of sand control completions, a recommended practice has been established.

Experience with Sand Control

Hydro Oil & Energy has installed approximately 230 screens, and more than 95 % of the screens have been installed in horizontal oil and gas producers. The remaining 5 % are installed in water production and water injection wells. Both the horizontal length and the complexity of the oil and gas wells vary. Up to 3000 m horizontal sections and multilateral wells have been completed. All horizontal wells, which require sand control, are completed with stand alone screen.

In the earlier years prepacked and single wire wrapped screens were often used, but now premium, mesh type screens are most common. Of the total number of screens run, approximately 80 % are premium screens, while 10 % are prepacked and 10 % are single wire wrapped screens.

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