Dual completion was for a long time used to produce wells perforated on several zones. This type of completion concerns especially the oil wells, but few or not used on the gas wells.
In order to improve the production in the upper zone of gas wells, a study was carried out on production gas wells with 2 layers and 3 layers in Hassi-Rmel's field. This field is located 500 km southward from Algiers in the Algerian Sahara and is one of the largest wet gas reservoirs in the world.
The gas-producing Hassi R'Mel field has three distinct reservoir horizons, zones A,B and C.
The zone A sandstones are composed of very fine grained sandstones which are locally clay-rich with anhydritic cementing in some places.
The zones B and C have very good reservoir quality with permeabilities to gas ranging from 300 to 1200 mD. Zone A also has very good reservoir quality for gas, however, it has lower permeability of generally less than 300 mD.
PLT recorded on these wells showed that the lower Zones B and C contribute to the majority of the gas production with the upper Zone A providing a lower contribution to the total production, in spite of an acidification of this layer.
The isolated zone C of some wells due to the water influx generated an increase in the flow of zone A.
This result pushes us to take in consideration the completion and to suggest to carry out a dual completion for the producing wells with several zones in order to improve the production of the zone A which is obstructed by the good potential of the zone C.
This study will make it possible to show the necessity to use a dual completion on the producing gas wells with several layers, in order to improve the production of the upper zone and for avoiding having a cross-flow from this one towards the lower depleted zone.
The results carried us made it possible to make a technical and economic study which will enable to see the impacts on the reservoir, on the well's equipment and investment costs.
The purpose of this presentation is to show: -the advantages and disadvantages from this completion on gas wells. -the ratio of the profit on the capital costs after these completion.
The producing gas wells with distinct reservoir horizons like Hassi R' Mel field presents problems of production. these problems are due:
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water influx
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cross flow
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low flow from the higher zone
A study was undertaken to see the solution to be brought in order to improve the potential of these wells, with the use of the dual completion.
Several papers were written about using dual completion to improve producing wells who produce from several zones.5–6–7 or to use new technique intelligent completion1–2–3–4
The goal of this study is to show the problems of these wells and the possibility and necessity to use one of these methods in order to improve potential of these wells who decreased due to the problems referred to above.
