Pressure Distribution about a Slotted Liner in a Producing Oil Well
- Frank G. Miller (U. S. Bureau of Mines)
- Document ID
- Society of Petroleum Engineers
- Transactions of the AIME
- Publication Date
- December 1941
- Document Type
- Journal Paper
- 137 - 151
- 1941. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 2.2.2 Perforating, 2.4.5 Gravel pack design & evaluation, 5.8.5 Oil Sand, Oil Shale, Bitumen, 5.5.2 Core Analysis, 4.6 Natural Gas, 3.1 Artificial Lift Systems, 1.2.3 Rock properties, 2.4.3 Sand/Solids Control, 1.11 Drilling Fluids and Materials
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The lower cost of producing oil from naturally flowing wells compared withproduction costs accruing from artificial lifting methods has stimulated muchresearch, with the joint purpose of extending the natural flowing life of wellsand of increasing the productivity of small wells. The laboratory investigationdescribed herein was made to determine the effect of a slotted liner on thepressure gradient in the vicinity of the wall of a flowing well. Flowrestrictions caused by the liner induce energy losses between the oil-bearingformation and the inside of the liner, which may be reduced by improved linerdesign, and thereby the flow capacity of wells may be increased. These losseshave been evaluated for rectangular slots of different sizes, and means aresuggested for reducing them.
The dearth of information concerning the nature of the flow of fluids fromunconsolidated sands through small openings in the walls of pipes-asrepresented by the flow of oil from an oil sand into a slotted liner-isacknowledged. Although the benefits to be realized by operators through the useof optimum liners is just beginning to be recognized generally, Coberly in 1937pointed out that the functioning of screen casing is an important factor in theproduction of oil. From his study on the selection of size of oil strings forwells in California, Parks concluded, in part, that the perforated section ofthe oil string deserves continued study, especially with respect to theselection of perforations.
The growing use of gravel packing resulting from certain research findingslends even more significance to the problem of selecting optimum liners, as theapplication of these methods usually requires slotted liners or other kinds ofperforated liners.
The present study was made to, obtain further information for the guidance ofengineers and operators in selecting slotted liners and to develop a laboratorymethod that may be used in analyzing possible pressure conditions surroundingmost types of perforated casings used in producing oil wells, so that thepresent inadequate fund of knowledge on this important subject may beexpanded.
Discussion of Problem
At the beginning of the investigation the following assumptions were maderegarding bottom-hole conditions of a producing oil well and the oil-sandreservoir it penetrates: (1) Conditions of steady-state flow exist, (2) asingle-phase homogeneous liquid is being produced, (3) no contaminatingmaterial (such as drilling fluid) is present between the liner and the face ofthe oilbearing sand, (4) the well is vertical and completely penetrates ahorizontal sand stratum of uniform thickness occurring between two impermeablestrata, and (5) the flow is wholly viscous.
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