WO2015147652A1

WO2015147652A1 - Tool and method for planning, constructing, developing, maintaining and abandoning of petroleum wells

Info

Publication number: WO2015147652A1
Application number: PCT/NO2015/050056
Authority: WO
Inventors: Tore FJÅGESUND
Original assignee: WELLBARRIER AS
Current assignee: WELLBARRIER AS
Priority date: 2014-03-25
Filing date: 2015-03-25
Publication date: 2015-10-01
Anticipated expiration: 2016-09-25

Abstract

The invention provides a tool for planning, constructing, developing, maintaining and abandonment of petroleum wells, comprising representation of a well or each well in a group of well categories, such as a well in the drilling, completion, intervention, workover or abandonment phase, wherein each well is represented by elements having a consistent shape and position of assembly, the assembly of the elements are arranged in a logical order or position so as to represent a functional well, wherein the elements comprises well barrier elements. The tool is distinctive in that the representation further comprises pressure curve data, including pore pressure and fracturing pressure, vertically aligned to the well elements and directly connecting well barrier elements and related pressure along the vertical representation of the well. Related method and use.

Description

TOOL AND METHOD FOR PLANNING, CONSTRUCTING, .DEVELOPI G, MAINTAINING AND ABANDONING OF PETROLEUM WELLS Field of the invention

The present invention relates to wells for petroleum exploration and production. More specifically, the invention relates to pressure harriers, safety, design, development, operation, maintenance and abandonment of we!!s. The invention provides a tool and a method for planning, constructing, developing, maintaining and abandonment of petroleum wells. The tool and method of the invention are useful during all phases of the life of a petroleum well.

Background of th invention and prior art

Well integrity, definition and location of well, barriers are important aspects when working on wells where petroleum reservoirs are exploited. Detailed drawings, such as "as built" drawings for barrier purpose, are often not available. Decision makers for construction and maintenance in the field will often find that the basis for decisions is missing and that there is a lack of overview of the well status. Wrong decisions, resulting in excessive spending and potential risk for health and safety, can be the result A comprehensive job for providing the basis for decisions and providing a correct overview will often be required in order to reduce the risk of wrong decisions.

Currently, many national regulators and industry standards require that well barriers are identified and employed to prevent discharge of hydrocarbons to the environment during drilling, well operations and production when exploiting oil and gas resources.

The standard Norsok D-010 rev. 4 gives examples on how this can be done by use of illustrations. However, current industry practice is that this is either verbally described or only partially done b use of illustrations. When using illustrations there are no templates or tools available to prescribe how the well barrier definition shall be presented in a consistent manner, and there is no clear way of connecting elements and pressure barriers of the well to prevailing pressure parameters of the well.

When making illustrations the individual engineers can spend several hours on masterminding an application such as Microsoft Visio, Microsoft Excel,

Microsoft Powerpoint or other applications to produce an illustration. As this is done by different people this has a tendency to end u as different looking graphical illustrations. Thus similar well cases might be drawn in different manners although they should have been identical.

As much as 4 ~ 8 hours can be spent on making an illustration from scratch, if minor changes are to be made to existing material this could also take several hours. Deciding where to set packers, casing shoes, mechanical plugs, cement plugs or other barriers, are procedures requiring great skill, overview and experience in order to avoid errors and maintain safety.

The inconsistency of the well representation can result in wrong decisions and extensive work that should be avoided. The objective of the invention is to provide an improved tool and a improved method and use thereof in order to construct and maintain petroleum wells over their life span, resulting in reduced failure rate of decisions and reduced work effort during construction,

maintenance and operation of wells.

With the patent NO 332 280, a tool was provided for increased reliability, reduced risk for making wrong decisions, and increased efficiency, when planning, constructing, developing, maintaining or abandoning wells. However, still a demand for improvements exists. The aim of the present invention is to improve the tool and method of NO 332 280. Summary of the invention

To meet the demand, the invention provides a tool for planning, constructing, developing, operating, maintaining and abandonment of petroleum wells, comprising representation of a well or each well in a group of well categories, such as a well in the drilling, completion, intervention, workover or abandonment phase, wherein each we!! is represented by elements having a consistent shape and position of assembly, the assembly of the eiements are arranged in a logical order or position so as to represent a functional we!!, wherein the elements comprises well barrier eiements. The tool is distinctive in that the representation further comprises pressure curve data, including pore pressure and fracturing pressure, vertically aligned to the well elements and directly connecting well barrier elements and related pressure along the vertical representation of the we!!. With the term verticaiiy aligned, it is meant that each element, barrier or point i the we!l, in the vertical direction down the well a!ong elevation or depth of the weli, corresponds to pressure plot data at identical elevation or depth position, making a realistic representation of the weli and the related pressure data at each and ever position. This means in practice that the direction of the well representing depth or elevation is parallel and corresponding to the pressure plot data at the identical depth or elevation of the well. This is achieved by arranging the well representation side by side to the pressure plot, aligning the vertical scale and dimension of the well representation and pressure plot. Real pressure and fluid data are used for the pressure plot, making it easy to see the effects of arranging barriers and elements at different position, facilitating the design, development, maintenance and abandonment of the well. This will be better explained in the detailed description below.

The term directly connecting well barrier elements and related pressure along the vertical representation of the well, means that the related pressure of any chosen barrier or position easily can be found by laterally displacing the elevation thereof into the pressure data represented in parallel. This will be better explained in the detailed descriptio below. Preferably, the shape and width of each element is proportionally correct but the vertical dimension of well elements, curvature and related pressure data ca be varied simultaneously, as controlled by a user of the tool. However, preferably also the vertically extending eiements have a proportional correct dimension, adjustable by the user to match the real well dimensions and pressure data. Even more preferable, the well barrier elements and well elements are consistently recognizable by having a distinctive shape, line type and/or width and a specific hatching or color for primary barriers and another specific hatching or color for secondary barriers, whilst the well pressure data is a pore- fracture pressure plot presented as pressure versus depth or presented as density versus depth.

The invention also provides a method for planning, constructing, developing, operating, maintaining and abandonment of petroleum wells, comprising representation of a well or each well in a group of well categories, such as a well in the drilling, completion, intervention, workover or abandonment phase, wherein each well is represented by elements having a consistent shape and position of assembly, the assembly of the elements are arranged in a logical order or position so as to represent a functional well, wherein the elements comprises well barrier elements. The method is distinctive by: including pore pressure and fracturing pressure, vertically aligned to the well elements and directly connecting well barrier elements and related pressure along the vertical representation of the well. Preferably, the shape and width of each element is represented proportionally correct but the vertical dimension of well elements, curvature and related pressure data, can be varied simultaneously. Most preferably, the well barrier elements and well elements are represented consistently recognizable by having a distinctive shape, line type and/or width and a specific hatching or color for primary barriers and another specific hatching or color for secondary barriers, whilst the well pressure data is represented as a pore-fracture pressure plot as pressure versus depth or presented as gradient-pressure versus depth. Preferably, the tool and method of the invention use or collect updated data for pressures in the well and preferably also the reservoir, from sensors in the well or wellbore, periodically or real time, manual or automated, providing a dynamic tool and method updated to real conditions. The invention also provides use of the tool or the method according to the invention, for planning, constructing, developing, operating, maintaining or abandonment of a petro!eum vve!l. Preferably, the use is for avoiding effects of failure of an element of a well system, particularly by reducing the risk for placing well barriers at wrong or inadequate position in the well. Pore and fracture pressure curves are commonly used for setting casing shoes. However, said prior use is a limited and very specific static use compared to the tool and method of the present invention, which is using the well data as basis and correlating said data of to the pressure condition at different depths in the well. However, setting of casing shoes is a disclaimed field of use for the most general embodiments of the invention,

Figures

The invention is illustrated with eight figures, of which:

Figure 1 is a cased well and pore-fracture pressure representation,

Figure 2 illustrates plug and abandonment,

Figure 3 illustrates drilling intermediate section out of surface casing in deep- water well,

Figure 4 illustrates dual gradient drilling to overcome insufficient formation strength behind surface casing in deep water wells,

Figure 5 illustrates conventional drilling,

Figure 6 illustrates a well completed with screen liner,

Figure 7 illustrates gas lift wells, and

Figure 8 illustrates managed pressure drilling.

Detailed description

The figures illustrate how the well and pressure data are represented, and how the representations can be used for planning, constructing, developing, maintaining or abandonment of a petroleum well.

Reference is made to Fig. 1 , illustrating a cased well and a pore-fracture pressure representation as related directly to the well elements, particularly the we!i barrier elements. Fig. 1 illustrate how the tool and the method of the invention clearly relate well barrier definition and/or critical points to pore and pressure plot. Preferably, the data are updated periodically or real time to real conditions in the well and wellborn.

A well barrier illustration is placed side by side with a pore and fracture pressure plot. The depth proportions below the mud line of the well barrier illustration and the pressure plot are identical. This is effectively achieved b creating the pressure plot on a scalable format and importing this to an editor where the well barrier illustration is created with depth proportions matching the pressure plot. Note that the pressure curves are always aligned with the wells mud line, and the total height of the plot is adjusted proportionally upwards although this will not have any correspondence with equipment above the mudline which has no significance in this concept. This allows to clearly relating a critical point in the well barrier illustratio to the pore and formation fracture pressure in the pressure plot by use of horizontal reference lines (C). The process is started by identifying the reservoir pressure represented by the pore pressure which is identified by drawing the first horizontal reference line (1 ). A pressure gradient line (2) is drawn onto the pressure plot starting at a user-defined point of interest, in this case being the pore pressure at the top of the formation of interest. By showing by intersection that the horizontal reference lines ^'(C) crosses the gas gradient line (2) between the pore pressure (3) and the fracture pressure (4) curve, it is clearly demonstrated that the critical barrier points are placed at a position where the well construction can handle the pressure.

The tool and method of the invention can be used to find and demonstrate the suitability of any point or position in the well, as illustrated in subsequent illustration examples.

A key benefit of the method and tool rests in the ability to quickly and effectivel set up the scalable proportions between the two main components, the barrier illustration and the pore and fracture pressure plot which then is used to clearly visualize that the well barrier definitions in the well are placed at depths where there is adequate formation strength to withstand any pressure originating from the pressurized formations or induced from surface. In contrast, prior art tools for establishing and documenting well barriers during planning, constructing, developing, operating, maintaining and abandoning petroleum wells does not c!ear! relate the critical barrier points to the actual and dynamic pressure regimes in the well. Reference is made to Fig. 2, illustrating a well during plug and abandonment. The purpose is to demonstrate sufficient formation strength at base of secondary we!! barrier plug. When the secondary abandonment barrier plug (C) is set at a depth where the production tubing is cut just above the production packer to avoid having to mill this, the formation strength at the base of the plug is insufficient to serve as a secondary barrier foundation in the shown example (intersection between critical points (C) and (2) is outside the strength value of the fracture line)...

Further reference is made to Fig. 3, illustrating drilling intermediate section out of surface casing in a deep-water well. The purpose is to demonstrate sufficient formation strength behind the entire length of the surface casing in case a hole is worn in the casing during drilling activity - this is critical as a hole in the casing with insufficient formation strength behind will cause loss of the primary we!! barrier (overbalanced fluid column) at the same time as the secondary barrier (surface casing) is lost). The planned drilling mud density is shown as curve (2), where this intersects the fracture pressure curve (4) we see that the formation strength is insufficient if a hoie is worn in the surface casing above the depth reference line (c). The formation behind the surface casing is only strong enough for overbalanced fluid densities less than given by gradient line (2*).

Figure 4 illustrates dual gradient drilling to overcome insufficient formation strength behind surface casing in deep water welis. The purpose is to demonstrate that by use of dual gradient fluid drilling we can overcome the problem referred to in Fig. 3. The planned drilling mud density is shown as curve (2), where this intersects the fracture pressure curve (4) we see that the formation strength is insufficient if a hole is worn in the surface casing above the depth reference line (c). By introducing a dual fluid gradient solution with a lighter fluid in the riser section of the well (2*), we will not be exposed to a risk if a hole is worn in the surface casing, yet having sufficient mud overbalance while drilling^' the hole section- Figure 5 illustrates conventional drilling. The purpose is to demonstrate sufficient formation strength at the starting point of the secondary well barrier envelope based on the potential pressure originating from the depth of the reservoir (1) intersecting the pore pressure curve (3), When the production casing (C) is set at a planned depth, the formation strength at this depth is sufficient to serve as a secondary barrier foundation in the shown example (intersection between critical points (C) and (2) is inside the strength vaiue of the fracture line (4)). This can be done for full gas filled well bores or for drilling with kick margin in which case a dual gradient line will be shown to represent the height of the allowed kick margin volume. Figure 6 illustrates a welt completed with screen liner. The purpose is to demonstrate sufficient formation strength at the starting point of both the primary and secondary well barrier envelopes based on the potential pressure originating from the depth of the reservoir (1) intersecting the pore pressure curve (3). This illustration is a continuation of Fig. 5 that was drilled with overbalanced fluid; whe completing the well with a screen liner, this will change the barrier envelope definition and also the intermediate casing will now become a barrier. When the production casing (C1) is set at a planned depth, the formation strength at this depth is sufficient to serve as a primary barrier foundation in the shown example (intersection between critical points (C1) and (2) is inside the strength value of the fracture line (4)}. With the intermediate casing (C2) set at the indicated depth, the formation st ength at this depth is insufficient to serve as a secondary barrier foundation in this shown example (intersection between critical points (C2) and (2) is outside the strength value of the fracture line (4)).

Figure 7 illustrates gas lift wells. The purpose is to demonstrate sufficient formation strength at the starting point of the intermediate casing/secondary well barrier envelope (C) based on the potential pressure originating from the applied gas lift pressure at surface (1) if this is accidentiy leaked into the B- annulus and applied on top of a hydrostatic columns of completion fluid in th B~ annulus. it can be seen in this example that with the intermediate casing (C) set at a planned depth, the formation strength at this depth is too weak to withstand a leaking gas lift pressure into the B-annulus (intersection between critical points (C) and (1) is far outside the strengt value of th fracture line (4). In this case the fluid in the B-annulus is likely to leak into the formation below the casing shoe. Once the liquid in the B-annulus is replaced with gas lift gas the pressure (2) at the casing shoe is below (inside) the fracture pressure curve (4)). if the fracture pressure curve in this case represents the fracture closure pressure, it may be risk assessed and contemplated to continue operation of the well. Note that this can be a very dangerous situation if the pressure at the casing shoe is above the fracture closure pressure after the annu!us is displaced to gas as this will cause continuous gas leak into the formation, sometimes with little possibility to detect loss of gas from surface when multiple gas lift wells are in operation.

Figure 8 illustrates managed pressure drilling. The purpose is. to demonstrate recommended surface pressure (C) during non-pumping activity when performing Managed Pressure Drilling, initially, due to ECD (equivalent circulation density) effects while drilling/pumping the downhole pressure is too high and there is a risk of losses to the formation in tight drilling windows. To compensate for this a lower mud density is used (2), this will however not have sufficient weight to overbalance the reservoir pressure (1) whe not pumping, so a surface applied pressure have to be applied (C) when tripping or making up pipe to avoid intersecting the pore pressure curve (3), In the example show we see that a surface applied pressure of 40 bar can be recommended to maintain reservoir overbalance when not pumping (ECD effect in place).

Even though some specific situations in the life of petroleum wells have been illustrated and discussed, many other situations can be represented or modelled easily, as the skiiled person will realize by studying this document. However, the scope of protection as defined by the present claims will cover any modification or combination as found obvious for skilled persons by studying this document. The tool and method of the invention may comprise any feature or step here described or iliustrated, in any operative combination, each such operative combination is an embodiment of the invention.

Claims

1.

Tool for planning, constructing, developing, operating, maintaining and abandonment of petroleum wells, comprising representation of a well or each well in a group of well categories, such as a well in the drilling, completion, intervention, workover or abandonment phase, wherein each weli is

represented by elements having a consistent shape and position of assembly, the assembly of the elements are arranged in a logical order or position so as to represent a functional well, wherein the elements comprises well barrier elements,

c h a r a c t e r i s e d i n that

the representatio further comprises pressure curve data, including pore pressure and fracturing pressure, vertically aligned to the well elements and directly connecting well barrier elements and related pressure along the vertical representation of the well.

2.

Tool according to claim 1 , wherein the shape and width of each element is proportionally correct but the vertical dimension of well elements, curvature and related pressure data, can be varied simultaneously, as controlled by a user of the tool.

3.

Tool according to claim 1 or 2, c h a r c t e r i s e d i n that the weli barrier elements and well elements are consistently recognizable by having a distinctive shape, line type and/or width and a specific hatching or color for primary barriers and another specific hatching or color for secondary barriers, whilst the well pressure data is a pore-fracture pressure plot presented as pressure versus depth or presented as density versus depth.

4.

Method for planning, constructing, developing, operating, maintaining and abandonment of petroleum wells, comprising representation of a well or each well in a group of well categories, such as a well in the drilling, completion, intervention, workover or abandonment phase, wherein each weii is

c h a r a c t e r i s e d y

including pore pressure and fracturing pressure, vertically aligned to the well elements and directly connecting well barrier elements and related pressure along the vertical representation of the well.

5.

Method according to claim 4, whereby the shape and width of each element is represented proportionally correct but the vertical dimension of well elements, curvature and related pressure data, can be varied simultaneously.

6.

Method according to claim 4 or 5, whereby the well barrier elements and well elements are represented consistently recognizable by having a distinctive shape, line type and/or width and a specific hatching or color for primary barriers and another specific hatching or color for secondary barriers, whilst the well pressure data is represented as a pore-fracture pressure plot as pressure versus depth or presented as gradient-pressure versus depth,

7,

Use of a too! according to any one of claims 1 -3 or a method according to any one of claim 4 - 6, for planning, constructing, developing, operating, maintaining or abandonment of a petroleum well.

8.

Use according to claim 7, for avoiding effects of failure of an element of a well system, particularly by reducing the risk for placing well barriers at wrong position in the well.