AU2016201797A1 - Horizontal well liner - Google Patents

Abstract

A liner for a horizontal well, the liner comprising a substantially hollow elongated body having a plurality of orifices in the liner body that each allow limited ingress of fluid into the liner body. Each orifice has a predetermined shape, size and spacing in the liner body. The shape, size and spacing of the orifices provide that pressure of fluid in an annular space located between the liner body and the horizontal well is substantially uniform along the horizontal well. 12 20.3 20.2 Fig. 1 20 30 7-' 77 -61 44 20.1 20.2 Fig. 2

Description

Brian Stone INVENTION TITLE: Η Ο (Ν ;-Η d (Ν (Ν AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT (Original) Ο σ^ο Η Ο (Ν Η Ο (Ν APPLICATION NO: LODGED: COMPLETE SPECIFICATION LODGED: ACCEPTED: PUBLISHED: RELATED ART: NAME OF APPLICANT: Brian Stone ACTUAL INVENTOR: ADDRESS FOR SERVICE: LORD AND COMPANY,

Patent and Trade Mark Attorneys, of PO Box 530, West Perth,

Western Australia, 6872, AUSTRALIA. TIORIZONTAL WELL LINER’’ DETAILS OF ASSOCIATED PROVISIONAL ΑΡΡΕΙΟΑΤΙΟΝ NO’S:

AustraliaiiProvisional Patent Application Number 2015905172 filed on 14 December 2015

The following Statement is a full description of this invention including the best method of performing it known to me/us: ο (Ν ;-Η (Ν (Ν σ^ ο ο (Ν Ό Ο (Ν

TITLE “HORiZGiNTAL WELL LIMER’’

FIELD OF INVENTION

[0001 ] The present invention relates to a liner for a well.

[0002] More particularly, the present invention relates to a perlbrated liner for a horizontal well.

BACKGRQUiND

[0003] Water wells are used for extracting ground water from underground aquifers, including for domestic, municipal, industrial and agricultural water supplies.

Vertical water wells are typically driiled from the ground surface through and below the water table penetrating into an underiying aquifer. A well screen or a slotted casing may also be installed into the well. The inserted well screen or casing consists of a metal or plastic-based tube having a wire wrap or openings spaced at regular intervals along its length. Water from the aquifer flows through the screen and into the well. A pump is used to draw collected water out of the well.

Vertieal water wells can be problematic when being used to extraet fresh ground water from aquifers, in particular from coastal aquifers. Coastal aquifers may include an underiying saline water wedge. Due to its higher density, saline ground water may form an underlying wedge-shaped layer under the freshwater. A degree of mixing, through dispersion and/or diffusion, may occur at the boimdary between the fresh and saline water.

The velocity at which ground water flows into the well screen or casing of a yertical water well fcommonly referred to as ^‘entranGe” or '‘approach” velocity) may lead to pressure losses (drawdown) in the adjacent freshwater aquifer Which can cause upwelling of the underlying saline layer and resultant contamination of extracted water. Ο (Ν ;-Η ci (Ν (Ν σ^ ο (Ν Ό Ο (Ν 3

Furihef, in order to l>e effectiye. vertical wells inust be drilled suiSciently deep such that they substantially penetrate the zone of saturation below the water table. This also inta-eases the risk of saltwater intrusion occurring at the boundary between the fresh and saline water.

For these reasons, a horizontal water well can altematiyely be used when extracting fresh ground water, particularly from coastal aquifers. Horizontal water wells comprise a well screen that follows a horizontal or inclined course through a length of the fteshwater aquiier. The well is arranged such that, at one point, the well screen is in flowable commumeation with a collection sump or pump. In use, ground W'ater passes through the porous w^ell screen and flow's along the eourse of the horizontal screen or casing to a collection location. Ground water may be then extracted using a pump.

The approach velocity that is required in the adjacent aquifer' for horizontal water wells is less than for vertical wells. This leads to felatively less pr^sure reduction (drawdow'n) in the adjaceni aquifer and. in turn, less risk of unwanted saltw'ater iniru.sion. Advances in directional drilling and global positioning technologies have improved the viability and availability of horizontal water wells.

[0010] Horizontal wells rnay still, however, lead to adverse pressure losses in the adjacent aquifer. In particular, for long horizontal wells, the transfer of water to the collection location causes hydraulic friction losses to occur along the length of the well. Accumulated hydraulic friction, plus related velocity head, results in lower pressure that may be transferred to the adjacent aquifer through the porous well screen or casing, particulariy near to the delivery end. The lower pressure may, similarly, lead to unwanted saline upWelling and intrusion.

The present invention attempts to alleviate, at least in paif, the aforei-nentioned pressure losses in horizontal wells. ο (Ν (Ν (Ν r- σ^ r- ο (Ν Ό Ο (Ν

SUMMARY OF THE INVENTION

[0012] In acGordanGe with one aspect of the present invention, there is provided a liner for a horizontal well, the liner coniprising a substantially hollow elongated body having a plurality of orifices in the liner bodyi wherein: the orifices allow limited ingress of fluid into the liner body; each ori fice has a predetenBined shape, size and spacing in the liner body; and the shape, size and spacing of the orifices provide that pressure of fluid in an annular space located between the liner body and the horizontal well is substantially uniform along the horizontal well.

[0013] The shape, size and spacing of the orifices may be collectively adapted to offset pressure losses occurring in the well.

[0014] The pressure losses may be due to accumulated hydraulic friction and velocity head acting on fluid in the liner.

[0015] The shape, size and spacing of the orifices may take into account an adopted initial entry loss at an upstream end of the well

The annular space may have a cross; sectional area that is between 30% and 50% of a total cross sectional area of the liner body.

[OG I7] The shape, size and spacing of the orifices may be predetermined to adjust for variations in hydraulic Conductivity in geological Strata adjacent to the well.

The shape, size and spacing of the orifices may be predetermined to accommodate variations in water table level adjacent to the well.

[0019] The annular space may accommodaie the variations in hydrauHc conductivity and/or water table level.

[0020] The annular space may cause lateral flows within the annular space to accoffiinodate the variations in hydmulic conductivity and/or water iable level. ο (Ν

The shape, size and spaeifig of the orifices may be predetermined to provide a uniforai rate of fluid inflov^f along the liner body. 9:1 (Ν(Ν σ^ο(ΝΌΟ(Ν ] The liner body may be ffi ade o fa poly ethylene m at eri al. The liner body may be made of a polyyinyl chloride material. The liner body may be made of a fibre re-enforced plastic material.

[0025] The liner body rnay be made of a metallic material.

The liner bodY may be made of steel.

[0027] The liner body may be made of stainless steel.

The liner body may be made of a metal alloy.

[0029] The horizontal well may be a water well.

The horizontal well may be an oil well.

[0031 ] The horizontal well may be a gas well.

[0032] In aeGordance with one further aspect of the present invention, there is provided a iiner for a horizontal injection well, the liner comprising a substantially hollow elongated body having a plurality of orifices in the liner body, wherein; the orifices pennit egress of fluid out from the liner body; each orifice has a shape, size and spacing in the liner body; and the shape, size and spacing of the orifices provide that pressure of fluid in an annular space between the liner body and %'eil is substantially uniform along the w'elh [0033] in accordance with one fiirther aspect of the present invention, there is provided a method for determining the shape, size and spacing of a plurality of orifices in a substantially hollow elongated body of a liner for a horizontal well, wherein the shap^ and sizes and the spacing that is determined provide that pressure of fluid in an annular spaee between the liner body and well is substantially uniforni along the length of the well. ο (Ν (Ν (Ν σ^ ο (Ν Ο (Ν [0044] pressure loss

The shape, size and spacing of the orifices may he detemiined using a plurality of mput parameters.

[0035] The input parameters may include accumulated hydraulic fiictipn acting on fluid flowing along the liner.

The accumulated hydraulic feictipn may be calculated using one or more measurements of flow rate, diameter, length and/f)r a roughness coefficient of the liner pipe.

The input parameters may inelude one or more error margin CGrreetions for hydraulic frietion, [003 8] The input parameters may include variable velocity head along the 1 iner body.

[0039] The input parameters may include adopted initial entry loss at an upstream end of the well.

BRIEF DESCRIPTiON OF DRAWINGS

The present invention will now be described, by way of example, with reference: to the accompanying drawings, in which:

Figure 1 is a cross sectional view of a horizontal well having installed therein a well liner according to a prefen*ed embodiment of the present invention;

Figure 2 is a side view of the well and liner of Figure 1 in a horizontal well installation; [0043] Figure 3 is a schematic side view of a horizontal w^ell installation consfi-ueted in a coastal superficial aquifer; and 4 shows a graph illustrating the relationship between cumulative and distance along the length of a horizonial well at design flow rate. ο (Ν ;-Η σ3 (Ν (Ν σ^ ο (Ν Ο (Ν

DETAI LED DESCRIPTION OF THE DRAWINGS

Referring to Figure I, there is shown in cross section a horizontal well, referred to generally by reference numeral 10, The w'eil 10 has a conventional well screen or slotted casing 12 comprising an elongated tubular body 14 inserted into the well 10. The well sereen or casing 12 has a spaced wire wrap Or series of slots along its longitudinal length adapted to painit water, or other fluids, to pass through the well screen 12. 5] The well 10 additionally has installed tberein a well liner 16 according to a preferred embodiment of the present invention. The liner 16 comprises a substantially hollow' elongated body 18 that extends, at least in part, along the longitudinal length of the well 10. Preferably, the body 18 extends along the entire longitudinal length of the W'ell 10, I'he liner body 18 has a cross sectional shape that is substantially circular and is made of a material having sufficient rigidity, durability, water-resilience and anticorrosive properties sneh as, for example, polyethylene, polyvinyl chloride, fibre re-enforeed plastic or a metal-based material such as stainless steel. A plurality of orifices 20 are formed in the liner body 18 that are each adapted to pennit the inflow' of ground water, or other fluid, into a centre 22 of the liner body 18. Whilst four orifices (20.1 to 20.4) are shown in the liner body 18 in cross section in Figure 1, it will be appreciated that, generally, the liner body 18 wdll comprise numerous orifices 20 and may, therefore, have more or less than four in cross section.

The liner 16 is adapted to twist or rotate w^hen inserted into the eonrse of the well 10. The elongated length of the liner 16 may, therefore, not neGessarily be straight or ameentric once fully installed into the well 10. A void 24 is located between an exterior surface 26 of the liner body 18 and an interior surface 29 of the well 10 bore. In the exemplary arrangement shown in Figure 1, the well screen or slotted casing 12 occupies the void 24, in part. It wdii be Ο (Ν (Ν (Ν σ^ ο Η Ο (Ν Η Ο (Ν 8 appreciated, however, that for horizontal wells not having a well screen or slotted casing inserted therein, the void 24 will: be substantially empty.

[0051] The void 24 has :a cross-sectional shape that is, preferably, substantially annular but not necessarily concentric. The total cross sectional area that is occupied by the annular void 24 is variable but is, preferably, between 30% and 50% of the total internal cross sectional area of the liner body 18.

[0052] Referring to Figure 2, there is shown a horizontal installation, being indicated generally by reference numeral 30, comprising the well 10, well screen 12 and well liner 16 of Figure 1.

[0053] The well 10 has been installed below' the ground surface 32 and follows a long course along a distance indicated by D, The installed well screen or slotted casing 12 and liner 16 pass a substantial distance through an aquifer 34 below an initial water table 36 and seiA'c as the collection conduit for the well installation 30.

The well installation 30 also includes a collection sump 38 and pump, or an alternative pump configuration. As shown in Figure 2, the discharge end 40 of the liner 16 is in floW''able communication with the cpllection sump 38 and/or puinp. in the ease of a sump, an annular seal 44 is installed around the circumferential surface of the liner body 18 which will ensure a Water-tight seal between the liner body 18 and well screen body 14 at its discharge end 40. A further seal 46 may also be in the base end 42 of the coiiection sump 38:.

[0056] In use, ground water fi-ora the aquifer 34 flows through the porous w'di screen or slotted casing 12 and through the orifices 20 in the liner 16. The ground w'ater then fiows along the course of the liner 16 in the direction indicated generally by reference numeral 48, The ground water collects at a Gollectjon location 38 and is extracted using a pump 50, as indicated by reference numeral 52.

The extraction of ground water causes a degree of fonnation loss (commonly referred to as draw'down) to occur in the adjacent aquifer 34, as indicated by reference Ό Ο (Ν ;-Η ci (Ν (Ν σ^ ο (Ν Ο (Ν 9 nunierai 54. The drawdo% causes the zone of saturation adjacent to the well to be reduced to an operating water table ΙεΛΐοΙ 56.

Flow in the liner 16 fesults in iriction and velocity head losses that cause aceumulated pressure losses within the liner 16. In addition, the orifices 20 at the upstream end 62 of the liner 16 maybe designed so that there is an adopted initial inflow loss {or, alternatively, an adopted outflow loss) equivalent to 5 to 10% of the cumulative tolal friction, velocity head and safety factor loses. The adopted initial entry los.s, into the liner 16, is indicated in Figure 2 by reference numeral 61. The entry loss thru the w^ll screen 12 is indicated a.s by reference numeral 52.

[0059] The hydraulic grade line 58 indicates the predetennined hydraulic grade within the liner 16 under design flow and adjusted watei· table conditions.

Without the presence of the well liner 16, the flow of ground water through the well screen 12 into the collection sump 38 would cause hydraulic friction and velocity head losses to occur along the length D of the well screen or slotted casing 12 and the accumulated pressure losses would be transfen'ed to the surrounding aquifer 34 through the well screen or slotted casing 12. These pressure losses would occur, in particular, towards the discharge end 40 which^ ip turn, would cause high inflow' rates and transfer of the low pressures to the adjacent aquifer 34. The reduction in aquifer pressure W'ould cause a corresponding drawdown to occur adjacent to the well.

The pressure losses and water table 56 reduction lead to unwanted upwelling to occur in respect to any layer of saline gTOund water that is present below tlie fre.shwatei· aquifer 34. Upwelling may lead to unwanted saline intrusion and resultant contamination of the extracted ground water.

The liner 16 that is installed inside the well 10 is intended to offset these pressure losses and related issues. Specifically, the shape, size: and spacing of the orifices 20 in the liner body 18 are predetermined so as to restrict inflow and ensure that the pressure of ground watei' in the annular void 24 between the liner 16 and well 10 is kepi substantially uniform along the length of the well. Preferably, the orifices 20 ensure that the adjacent ground water pressure is substantially uniform along the distance D of the. Ό Ο (Ν ;-Η cd (Ν (Ν Ο σ^ ο Η Ο (Ν Η Ο (Ν 10 well 10 due ίο the predeterhlined required head losses across the orifices 20 and resulting uniform rate intlow.:

Offsettffig the pressure losses to achieve substantially imiform adjacent ground water pressure suhstahtially mitigates the risk of saline upwelling occuning, in particulffl", near the discharge end 40. The UihfbiTnity of pressure, in turn, provides for a uniform rate of areal fluid inflow along the elongated length of the liner body 18.

[0064] The person skilled in hydniulies will appreciate that pressure loss (h) through an orifice in a iluid-carFying pipe varies as flow squared (Q^ and tliat hydraulic friction and velocity losses occurring along the pipe are also closely related to Q^, Because of this relationship, the orifices 20 may he calculated such that the head loses of entry into the liner 16 substantially match the cumulative head loses at any point along the liner 16.

[0065] The amount of hydrauiie friction calculated as part of determining and selecting the shape, size and spacing of the orifices 20 may be calculated using known and applicable hydraulic mathematical methods such as, for example, the Hazen and Williams or Colehrook-White equations taking into account a plurality of input parameters.

[0066] The input parameters may include adopted design flow, the liner’s 16 diameter and length D and roughness coefficients for the liner 16. The roughness eoefficients that are utilised, preferably, take into account one or more spatial and/Or temporal adjustments for the liner 16 such as, for example, variationSi in roughness that occur due to the long-term effects of corrosion.

Generally, the hydraulic friction calculations that are perfonned will be based on the principle that net cumulative hydraulic friction in a well, assuming substantially uniform flow, is appro-ximately 33,3% of die friction that would apply if the design flow occulted over the total length of the well. For conduits having uniform inflow rates and increasing lateral flows, total cumulative head losses may, therefore, be ealeulated as; 0:333 X L x h/ Ό Ο (Ν ;-Η ci of (Ν (Ν σ^ ο (Ν Ό Ο (Ν 11

wlvere L is the effective liner length, and hf is head loss in meters per unit conduit based on the design flow of the horizontal welL

It will be appreciated that the hydraulic friction values that are calculated using these methods are estimates only and contain a degree of inherent error (perfect friction: coefficients being the reserve of the pure mathematician). Error safety margin corrections within appropriate hydrological engineering tolerances are, therefore, also taken into account when detemiining the shape, size and spacing of the orifices 20 in the present invention. Error safety margins of between 10% and, !5% may, for exampie, be added into the calculations.

[0069] The orifices 20 are, further, selected to mitigate pressure losses that would occur as a result of variable velocity head occurring along the liner 16.

[0070] Velocity head (Yti) is, preferably, calculated using the formula:: V, - V^/2g where V is the liner flow velocity (meters / second) and g represents the aeceieratiGn due to gravity (m eters 7 second'^), Λ person skilled in hydraulics will further appreciate that, when total cumulative fluvial head losses are known, due to fiaction and velocity head, a proportion of these losses (typically, 5% to 10%) provide a basis for limiting inflow rates of ground water at the upstream end 62 of the well 10 and ensuring that inflow rates will be as determined along the total well length. The determination of the shape, size and spacing of the orifi ces 20, therefore, also takes into account adopted: initial entiy^ loss occurring at the upstream end 62.

[0072] As illustrated in Figures 1 and 2, the orifices !20 arc located CGnsistenily about the circumferential surface of the liner 16 and the spacing of the orifices 20, in gen eral, increases towards the discharge end 40 of the w ell screen body 1,4.

[0073] The diameter of each of the orifices 20 is, prefembly, selected sueh that betw'een two and four orifices are provided for each meter length of the liner 16 at the upstream end 62. The spacing increases towards the diseharge end 40.

Ο (N

(N (N

C-' σ^ O (N kO o (N 12 [0074] The adopted initial entry loss that is taken into account when selecting the shape, size and spacing of the orifices 20 is critical to ensure that controlled rates of inflow are aehie\^ed at the upstream end 62 of the liner 16. The adopted initial entry loss is also used to help determine the required diameter of the orifices 20, and to limit the number of orifiees 20 that must be present in the liner 16.

It will further be appreciated that the geological composition and properties of the strata and aquifer 34 surrounding the well 10 may not be homogenous. The permeability (and related hydraulic conductivity) of the sirata and the water table level may vary along the elongated coui'se of the well. The shape, size and spaeing of the orifices 20 that are calculated may take these variations into account and ensure that unifonn pressure and required rates of fluvial inflow are achieved along the liner 16 notwithstanding such geological variations.

[0076] Figure 3 shows a profile of a 500 m long horizontal well showing aitemative ioeations for collection locations 68^ 70,1 and 70.2. Colieefion loeations influence the cumulative head loss in liner pipes and may pennit utilisation of more economical (smaller diameter) well screens and liner pipes.

[0077] Drilling profiles 66 and 80 indicate differences that may result due to smaller diameter well screens. The curved sections of the profiles, may be abandoned after completion of the horizontal section 82 or, alternatively, the original access to the horizontal well may be utilised for installation of a collection pump.

[0078] Figure 3 shows hydiOgeoiogical data for a horizontal well parallel to a coastline, iudicated data includes sea level 78, initial water level 76, invert of screen 82 and underlying aquatard 72.

[0079] Figure 4 shows a graph 84 that illustrates the relationship between cumulative pressure loss, shown on the y axis 86, and tii.stanGe along the elongated length of a 500 metre long horizontal well, shown on the x axis 88.

[0080] The values depicted in the graph 84 were calculated based on an assumed well effective lengfli D of 500 metres. If a collection sump were located eentrally wifliin the well installation (such as, for example, sump loeation 70.1 in Figure 3), then the Ό Ο (Ν (Ν (Ν σ^ ο (Ν Ό Ο (Ν 13 effective length would be halved,, and the diameters of the well screen: 12 aiid liner 16 could be reduced accordingly.

The line 90 represents total cumulative pressure loss, including taking into account fiiction and velocity head, that is experienced at any point along the well section. The dotted line 92 represents friction at any point along the well section. The adopted: initial entr>' loss into the liner is indicated by reference numeral 94,

As indicated by reference numeral 96, the graph values: may be used as a basis for calculating the relative pressure loss and the size, shape and Spacing of orifices 20 of a liner 16 for a well for each 5 or 10% section of the liner 16, Each sectiQn of the liner 16 will comprise substantially common orifice spacing. Flow' corrections in order to conform to the shape of the cumulative pressure loss curve 90 would adjust automatically ip lateral flows in the annular space 24 inside the well. 13] The number of orifices that may be required for each section of liner 16 is calculated using mathematical fonnulas and/or algorithms, as appropriate. The following fomula may. by way of example, be used (using units eommonly used in the United States) as part of these calculations: Q=20€(^k^ where Q is flow (in gpm), C is an appropriate co-efficient, d is the diameter of each the orifiees fin inches) and h is head loss (in feet), A typical value that will be given for eo-efficient C is 0;61, Where, however, entry holes are drilled into a HDPE pipe, the wall thickness of the pipe may exceed the diameter of each orifice. In these eases, a value of 0.7 may be given to co-efficient C, and the opening would be cla,ssified as; a square edge nozzle.

[0084] it is: principally envisaged that the liner 16 that is the subject of the present invention will be used to improve the performance and efficiency of horizontal well installations used for extracting groimd water. In particular, the liner 16 will significantly improve the extraction of ground water from freshwater coastal aquifers residing above saline-water wedges. It will be ,appreciated, however, that the liner 16 may also be used Ο (Ν (Ν (Ν r- σ^ r- ο (Ν Ό Ο (Ν 14 to improve other t>pes of fluid-Based horizontal well installations such as, for example, oil

The liner 16 may, fhrther, be used to improve the perfonriance and efficiency of horizontal injection-type wells. Horizontal wells may be drilled in order to facilitate the injection, re-charge, disposal or in-ground treatment of fluids such as excess water or effluenis, into geological strata. Such tyiaes of wells vvouM, similarly, be provided with a perforated screen or Gasing that extends along the welTs longitudinal length and governs the discharge and outflow of fluid if om the well into the adjacent strata.

The same principles and issues described above for extraction wells become similarly manifest during the operation of injection w'ells, albeit in reverse. This includes accumulated hydraulic friction that acts along the elongated course of a horizontal injection well. The present liner 16 may, therefore, be inserted inside an injection well in order to provide uniform pressure in the space between the liner 16 and injection sereen. The liner 16 will substantially control the rate of fluid discharge through the well screen into the surrounding strata. 7] Modifications and variations as would be apparent to a sMlled addressee are deemed to be within the scope of the present invention.

Claims (14)

1. A liner for a horizontal well, the liner comprising a substantially hollow elongated body having a plurality of orifices in the liner body, wherein: the orifices allow limited ingress of fluid into the liner body; each orifice has a predetermined shape, size and spacing in the liner body; and the shape, size and spacing of the orifices provide that pressure of fluid in an annular space located between the liner body and the horizontal well is substantially uniform along the horizontal well.

2. A liner for a horizontal well according to claim 1, wherein the shape, size and spacing of the orifices collectively offset pressure losses occurring in the well due to accumulated hydraulic friction and velocity head acting on fluid in the liner,

3 . A liner for a horizontal well according to claim 1, wherein the shape, size and spacing of the orifices take into account adopted initial entry loss at an upstr eam end of the well.

4. A liner for a horizontal well according to claim .1,. wherein the shape, size and spacing of the orifices accommodate variations in hydraulic conductivity in geological strata adjacent to the well,

5. A liner for a horizontal well according to claim 1, wherein the shape, size and spacing of the orifices accommodate variations in water table level adjacent to the well.

6. A liner for a horizontal well according to claim I, wherein the shape, size and spacing of the orifices provide a uniform rate of fluid inflow along the liner body.

7. A liner for a horizontal well according to any preceding claim, wherein the annular space has a. cross sectional area that is between 30% and 50% of a cross sectional area of the liner body.

8. A liner for a horizontal well according to any preceding claim, wherein the shape, size and spacing of the orifices are determined using a plurality of input parameters, the input parameters including accumulated hydraulic friction acting on fluid flowing along the well.

9. A liner for a horizontal well according to claim 8, wherein the accumulated hydraulic friction is calculated using measurements of flow rate, diameter, length and/or a roughness coefficient of the liner body section.

10. A liner for a horizontal well according to claim 8, wherein the input parameters include variable velocity head along the liner body. 11. A-finer for a horizontal well according to claim 10, wherein the variable velocity head is calculated as = i^/%, where Fis liner flow velocity and g is acceleration due to gravity.

12. A liner for a horizontal well according to claim 8, wherein approximate cumulative total head loses are calculated for the liner using the formula 0.333 x L x hf where L is a total length of th e liner and h f is head loss in meters per unit length of the liner.

13. A liner for a horizontal well according to claim 8, wherein the input parameters include adopted initial entry loss at an upstream end of the well.

14. A liner for a horizontal well according to claim 8, wherein the input parameters include one or more error margin corrections for hydraulic friction.

15. A liner for a horizontal injection well, the liner comprising a substantially hollow elongated body having a plurality of orifices in the liner body, wherein; the orifices permit egress of fluid out from the liner body; each orifice has a shape, size and spacing in the liner body; and the shape, size and spacing of the orifices provide that pressure of fluid in an annular space between the liner body and the well is substantially uniform along the well.