FIELD OF THE INVENTION

[0001] The present invention relates to a method for the construction of an arrangement for Extended Reach Wells (ERW) for the production, transport, and exploitation of mineral layers, a well arrangement constructed in this manner, and a method for the construction of a network of ducts for the transport and storage of fluids. More specifically, the present invention relates to a method for the production of oil and gas, a method for the transport and storage of the oil and gas thus produced, a method for the drilling of long-distance petroleum and gas wells, and a method for the exploitation of reservoirs of petroleum and gas.

[0002] The present invention relates to a method of drilling and exploitation, production, transport and storage which includes the initial drilling of a well of medium distance and at least one multilateral well of medium distance in the initial direction of drilling, and in at least one direction of the reserve which it is intended to use for production. The method allows for very distant areas of the reserve to be reached, this being achieved with the aid of conventional technologies and at low cost. The method is applied principally in extremely deep water as well as in land areas with difficult access.

BACKGROUND TO THE INVENTION

[0003] Long-distance wells have long been used extensively in industry. In the past few years these wells have become viable for the exploitation of fields, extending the service lives of some and increasing the reserves available. Nevertheless, the applications of long-distance wells are limited by prohibitive costs resulting from the specifications for the drilling probes and other problems of a technical nature, as well as the precarious remote control, excessive torque and pull, difficult cleaning from the well hole in long sections with high inclination angles, insufficient weight on the drill bit, and environmental considerations. However, applications for long-distance wells need not be limited solely to the area of production, but can also be applied to the sector of transport by pipeline, in which long-distance wells connected in series can be constructed for the transport of gases and/or liquids.

[0004] Current technology of long-distance wells is based on a single well, with considerable problems in access to remote areas due to the long distance from one single well. On the other hand, current technology in deep water consists of installing a floating production unit in waters of lesser depth and the use of wells of wet design and underwater manifolds, combined with flexible lines of very high cost as well as long-distance wells. There are, however, financial and technical limitations on this distance.

[0005] There are also serious problems with flowing via flexible lines due to the low temperature of the water at the bottom of the sea where the flexible lines are located. Long flexible lines are subject to problems of high viscosity of the fluid, the depositing of paraffin, and the formation of hydrates, as a consequence of the low temperature and high pressure. Technologies which make long-distance operation possible can reduce the length of flexible lines and even do away with them altogether, passing the fluids produced to be discharged for preference inside the well and in heated areas.

[0006] U.S. Pat. Nos. 5,735,350, 6,158,531 and 6,263,987B1, the disclosure of which is hereby incorporated by reference, relate respectively to drilling and completion with the use of conventional casing and in one stage, with the actual drilling column being used as the casing for vertical and lateral wells for long-distance production. The focus of these patents is the simultaneous performance of the drilling and completion of a petroleum and gas well. No provision is made for the production of oil and gas without casing for the well. The technology described is applied principally to wells drilled on the Continental shelf.

[0007] On the other hand, current drilling processes include the drilling of a principal well or principal direction, and other multilateral wells for the exploitation of the field. This involves the completion of a number of drilled wells, activities which are both slow and burdensome.

[0008] U.S. Pat. Nos. 5,551,521 and 5,894,897, the disclosure of which is hereby incorporated by reference, relate to methods and equipment for cementing a drilling column in the location of the well in order to drill and complete oil and gas wells simultaneously. The object of these publications is the cementing of the drilling column as a casing for the well.

[0009] However, the patent literature relating to vertical wells or drilling processes invariably involves the completion of the drilled wells or only the drilling of the petroleum and gas production well.

[0010] On the other hand, patents relating to multilateral wells likewise relate to the completion of the drilling work.

[0011] The transport of petroleum and gas produced in multilateral land-based wells is carried out in conventional pipelines, this being a process entirely within the public domain. The transport of petroleum and gas produced in underwater multilateral wells is limited by the difficulties incurred by deposits of paraffin and the formation of gas hydrates on the pipe walls, brought about over long distances in deep water at low temperature. Technical proposals have been made for avoiding paraffination and the formation of hydrates, as well as the thermal insulation of the flexible pipes which transport the petroleum, but the solutions proposed normally involve a greater or lesser increase in costs.

[0012] U.S. Pat. Nos. 4,660,606 and 4,556,343, the disclosure of which is hereby incorporated by reference, describe a method and an offshore installation intended to receive, store, and transfer crude petroleum from at least one well located on the seabed. These patents make provision for the use of pipes which are suitable for the transport of oil between the production wellheads and the pipe which collects the oil from various different wells and conveys it to the installation forming the object of the patent. The pipes start from the seabed and, depending on the size of the production field and the scale of the installations to be used, may have to cover considerable distances over the seabed until reaching the installations with which they are to be integrated.

[0013] U.S. Pat. Nos. 4,770,199 and 4,781,207 the disclosure of which is hereby incorporated by reference, relate respectively to a method for the transporting of heavy oils and a method for transporting viscous heavy oils, in which an emulsion of the oil in water containing an organic emulsifying compound is transported and subsequently separated again into crude oil and water. These patents say nothing about the physical means by which the transport of the emulsion of oil in water is carried out, and still less about the chemical aspects involved.

[0014] U.S. Pat. No. RE28,978, the disclosure of which is hereby incorporated by reference, describes an underwater system for the production and transport of fluid minerals, which includes a collection network for the product provided with production satellites in which the gas-oil-water ratio from each well is periodically tested and the flow rate automatically controlled, and the fluids of which are transported through individual pipes to the underwater product collection stations, and then as far as the surface though rigid pipes amounting to half the mass of the seawater. In the event of excessive pressure arising in the pipe which transports the fluid from the seabed to the surface, this system makes provision for a section of the pipe to be an escape section, which would break, and around which the fluid would be collected in an inverted funnel, so restricting losses of fluid to a minimum.

[0015] U.S. Pat. No. 5,154,741 the disclosure of which is hereby incorporated by reference, describes a system for the production and transport of oil and gas in deep water, including a wet “Christmas tree”, a vertical two-phase oil and gas separator, a gas cooler, a vertical tubular scrubber, a motorized pump, and a platform on which a speed variator for the motorized pump is located, a pressure relief valve to provide simultaneous control on the gas pipe, the scrubber, the two-phase separator, and a programmable logic controller. The passage of the fluids between the production wellhead and the Christmas tree makes provision for the use of at least one pipe running on the seabed. The passage of the oil and gas on the basis of the system described in this patent as far as the production plant makes provision for equipment for artificial elevation, and is carried out via a separate oil pipe and gas pipe, running on the seabed and crossing the seawater mass as far as an offshore platform situated on the surface.

[0016] As can be seen, all the patents referred to make provision for at least one pipe extending over the seabed in half the fluid mass, for the transport of the fluids produced by the wells as far as a specific underwater installation, from which the fluids are conducted by at least one further pipe as far as the production installations located on the surface.

[0017] In addition to the difficulties encountered with the depositing of paraffin and the formation of gas hydrates on the inside walls of the pipes which run long distances in deep water at low temperature, there is also an increased risk of leaks of the fluids and the pollution of the surrounding environment through which the pipes run, which increase in proportion to the quantity and length of the pipes used in the transport of the fluids.

[0018] Another disadvantage of the processes and methods of the prior art is that they all require the use of various items of equipment and accessories for transporting the fluids from the underwater petroleum fields, in quantities which are proportional to the number of petroleum and gas wells in the production group: wellhead equipment, Christmas trees, manifolds, well production lines, risers, gas pipes, oil pipes, and separators, all of which incur increased costs for installation and maintenance.

[0019] Another aspect is that the current petroleum production systems in deep water necessarily involve the continuous use of production platforms, with the high costs which these incur. It is normally necessary to make use of a number of platforms, depending on the depth of the water in which the wells being drilled are located. The principal patents for underwater production of oil and gas are analyzed hereinafter.

[0020] U.S. Pat. No. 5,899,637, the disclosure of which is hereby incorporated by reference, describes offshore production and storage equipment for petroleum and the respective method of installation in which the oil is produced and stored in tanks fixed to the deck of a concrete raft which is towed and submerged by the use of seawater as ballast, and kept on the seabed close to the oil production site. The oil is removed from the submerged tanks by a tanker vessel by the introduction of seawater into the submerged tanks. This patent presupposes the use of at least one additional pipe for moving the oil from the production station or from the collecting point located on the surface to the submerged tanks, with all the disadvantages already known, deriving from this being conveyed at the low temperatures of the water at the bottom of the sea (paraffin deposits on the interior of the pipe and the formation of hydrates). In addition to this, additional costs are incurred by the equipment characteristically used in this method (concrete raft, tanks, additional production and water lines) and the respective associated services (tug, ballasting and submerging the raft and tanks, the introduction of water into the submerged tanks, the installations, the control systems, and so on).

[0021] U.S. Pat. No. 5,330,293, the disclosure of which is hereby incorporated by reference, describes a system for the production and storage of petroleum, comprising the use of a large platform on tensioned legs in which a number of “risers” are used, which allow for freedom of vertical movement, and which therefore involve additional special structural requirements for floatability and arrangements to provide adequate support, restricting lateral movement but without the very high additional loads being applied to the platform. With the use of the “risers” this undoubtedly will incur substantially greater costs than those involved with the technique described and claimed in this present patent. U.S. Pat. Nos. 5,439,321, 4,913,238, and 4,556,340, the disclosure of which is hereby incorporated by reference, envisage hydrocarbon production systems which make use of floating structures, associated or not with tensioned-leg platforms, with the sheltered production deck being free to carry out vertical movements (“heave”) close to the surface, and being equipped with wellhead equipment which is connected or not by flexible risers to underwater wells. In this way, in all the patents cited in this paragraph, the production from each underwater well is processed individually, always requiring production lines, wellhead equipment, and risers; essentially, all the normal individual items of equipment for each well, which incurs a multiplication of the costs for the production equipment. There are also disadvantages associated with conveying through different pipes at low temperatures through water on the seabed (depositing of paraffin on the inside of the pipes, formation of hydrates), which multiply at least proportionally as a function of the quantity and length of the pipes used, such disadvantages being minimized by the process according to the invention described hereinafter.

[0022] U.S. Pat. No. 4,653,960, the disclosure of which is hereby incorporated by reference, makes provision for a crude oil separator and an offshore submersible storage apparatus which can also form a stable platform, in that an offshore structure or vessel for the drilling and production of petroleum products can be placed in position in a removable manner. This patent makes provision principally for the separation of crude oil and its storage, with the apparatus, being movable, also being capable of serving as a mode of transport for the products in the storage containers to another maritime installation for processing the petroleum produced.

[0023] U.S. Pat. No. 4,452,312, the disclosure of which is hereby incorporated by reference, describes a modular underwater oil production plant having at least one satellite unit, the product of which is conducted via a collector pipe to a central structure in which operational modules are grouped. Provision is made for the use of production heads and “templates”, and the installation of the production plant in excavations made on the seabed, with all the costs which the equipment and services associated with this will certainly incur.

[0024] U.S. Pat. No. 4,273,066, the disclosure of which is hereby incorporated by reference, envisages a method for the release of oil from an offshore well to the coast, comprising supply stretches for the oil from the well to a floating storage vessel stationed close to the well, and the transfer of the oil by means of a flexible pipe from the floating storage vessel to a service petroleum vessel which runs between the coast and the floating storage vessel. This patent makes provision for at least two lines for the passage of the fluids, one between the well and the floating storage vessel and the other between the latter and the service vessel, incurring the disadvantages of the formation of paraffin and hydrates in the submerged lines at low temperatures and high pressures, with the additional costs of the transport of the products via the petroleum vessel to the coast.

[0025] U.S. Pat. No. 4,152,088, the disclosure of which is hereby incorporated by reference, comprises offshore petroleum field production equipment with a production platform anchored to the seabed at the drilling site. It comprises a pivoted column connected by means of a universal Cardan coupling joint to a base anchored on the seabed, in connection with a floating gas burner located remotely for burning off the gas extracted from the oil. The production equipment items of the underwater wells are individual items, and the system makes provision for production lines and gas lines to the burner running over the seabed.

[0026] U.S. Pat. No. 4,762,180, the disclosure of which is hereby incorporated by reference, provides for a modular completion system close to the surface, which positions the production heads of the wells in a calm area beneath any significant wave activity, but within the operational range of divers for maintenance and inspection, in which each underwater well is provided with its own “riser”, a tensioning buoy on the riser, and a production well tree mounted on top of the riser buoy. The fluids produced are passed from the well tree to the floating production platform by means of flexible risers suspended in a catenary curve of sufficient length as to allow the platform to be maneuvered so as to be positioned for drilling or workover of any of the various templates which it serves.

[0027] U.S. Pat. No. 4,211,281, the disclosure of which is hereby incorporated by reference, envisages a multiple-articulated well production system in deep water for the handling of fluids produced from a number of individual wells drilled in deep water in different parts of a field, and the conveying of the fluids from the production wells to a surface production platform by means of a central riser.

[0028] U.S. Pat. Nos. 5,255,744 and 5,341,884, the disclosure of which is hereby incorporated by reference, envisage an underwater production system and methods for the connection of pipes in a “manifold”, and adjacent satellite wells in which the satellites are connected to the manifold via production pipes which run at a distance between each satellite well and the manifold, supported on the seabed and with half the mass of seawater.

[0029] As can be seen, the petroleum production systems in deep water which currently exist make use of individual items of equipment and individual production pipes for each well, associated with the manifolds or Christmas trees which collect the fluids produced from the various different wells and transfer them to additional lines which, in turn, travel via the production risers to the surface platforms equipped with petroleum production plant.

[0030] The different depths of the sea in which the wells concerned are located also require that the load losses due to the flow in the production lines be kept to a minimum in order to optimize the production from the wells, impose the use of more than one production platform per production field, and so substantially increase the costs of production and maintenance of the equipment, as well as the other individual costs of the equipment per well and those of the production pipes laid on the seabed, individual wellheads, manifolds, and “Christmas trees”.

[0031] Another disadvantage of these systems is associated with the exposure of the large number of different items of equipment of the wellheads, Christmas trees, manifolds, pipes, lines, collector stations, satellites, risers, and the fluids which circulate within them, to the adverse conditions of high pressure and low temperature present during the movement, consequently resulting in the depositing of paraffin inside the pipes and the formation of hydrates, which in the future will require cleaning operations, maintenance, or even the repositioning of the equipment and pipes at extra cost which will undoubtedly be substantial.

[0032] In addition, in order for the pipes to be grouped together for production, individual completion services will be required, which incur the costs of the immobilization and movement of the platforms, incurring heavy operational, service, and maintenance costs, in addition to the other well operations inherent in completion which precede the commissioning of these pipes, and the time taken (down-time) inherent in the other actions involved in completion services.

[0033] Accordingly, all the patent literature relating to the drilling of petroleum and gas wells stipulates that these must invariably be provided with casing, up to the actual drill pipe itself, such as in U.S. Pat. No. 6,263,987B1. When applied in deep water, the processes described become extremely expensive and slow.

[0034] Accordingly, despite the developments which pertain, the prior art still requires drilling processes for oil and gas wells which involve multilateral long-distance wells in deep water without any type of completion of the drilled well, and with the use of one single surface platform for all the wells in production, such processes being described and claimed in the present patent.

SUMMARY OF THE INVENTION

[0035] In a simplified manner, the method for the construction of an arrangement of long-distance wells for the production, transport, and exploitation of mineral deposits, the arrangement of the wells thus constructed, and a method for the construction of a pipe for the transport and storage of fluids according to the invention comprises the initial drilling of a medium-distance well. At least one other multilateral medium-distance well is drilled in the same direction as the first, and in one or more directions into the reservoir which is to be taken into production, with the aim of their ends meeting or coming close, there being no type of completion and casing for the multilateral drilled well(s). The production from the wells is effected by pressure differential, the fluid flowing from the well of greater pressure into the well of lesser pressure.

[0036] The invention also comprises the drilling of wells in series to be used as transport pipes. These wells are connected hydraulically, in such a way that the resultant distance is proportional to the number of wells drilled; i.e. infinite number of wells, infinite distance.

[0037] In addition, the present invention makes provision for the connection in series of a principal well and at least one multilateral well, in order to supplement the resultant distance and to drain distant areas of the reservoir.

[0038] The invention also makes provision for the connection of a series of two or more wells in order to increase the resultant distance and to transport gases and/or liquids between distant areas.

[0039] The invention likewise provides for arrangements of wells drilled at such long distances as may be necessary, using the technology of medium-distance wells.

[0040] The invention likewise provides for arrangements of wells drilled at long distances in which only the main well needs to be connected to the production unit.

[0041] The invention likewise provides for arrangements of wells forming a network for draining reservoirs of mineral layers.

[0042] The invention likewise provides for arrangements of long-distance wells which does away with the need to break the reservoir in order to obtain the fluids produced.

[0043] The invention additionally provides for the possibility of producing fluids via long-distance wells doing away with the use of individual items of equipment for each well, with great savings in costs and environmental protection.

[0044] The invention likewise provides for a method for the construction of pipes in series and/or in parallel, forming a network for the transport and storage of fluids produced from medium-distance wells and connected hydraulically.

[0045] The invention likewise provides for a production method for mineral layers in which the flowing of the fluid produced is effected from a well of greater pressure to a well of lesser pressure.

[0046] The invention likewise provides for a network of wells for a mineral layer in which only the principal well needs to be completed.

[0047] As can be easily verified on the basis of the considerations set forth in this text, the disadvantages determined for the prior art in the drilling of long-distance multilateral wells, such as high running costs of the multiplicity of equipment, as well as environmental corrosion, are greatly reduced or even eliminated with the method proposed by the present invention.

[0048] According to the invention, therefore, the method comprises the drilling of an initial well and a number of other multilateral directional wells, following the preliminary indications from geological studies, which allows for the formation of a network of underground channels with the aim of obtaining the best possible use of the fluids present in the reservoir.

[0049] According to a preferred embodiment of the invention, the initial well directional well.

[0050] According to another embodiment, the initial well a multidirectional well.

[0051] According to another embodiment, the initial well is a vertical well.

[0052] The flow from the reservoir is associated with the collection in production of the multilateral wells which are drilled. The production from the wells of the network is incurred by the difference in pressure, causing the flow of fluids from the wells with greater pressure in the direction of the well with lesser pressure. The flow of the fluids is interrupted by equipment installed on this lower pressure well, to a production plant located on a platform on the surface of the sea. Depending on the nature of the fluid, the equipment used may be a pump or a compressor.

[0053] The practice of the invention dispenses with the operations of completion and casing of each multilateral well, it being only necessary to install casing and complete the well of lesser pressure which is interlinked with the production platform.

[0054] According to the concept of the invention, the operations of specific drilling, the connection of the wells, and the equipment used in the operations are those commonly used in the state of the art, and do not constitute the object of the invention.