Abstract:
A system and a method for the artificial pneumatic production of oil and gas which is self-supplied is provided. The well&#39;s originating gas separates in a skid of separation of oil and after gas is rectified, gas is injected again into the well; the gas injection is made to a pressure enough to lift the oil-gas mixture inside the well. The excess of gas is exhausted toward the closer processing station.

Description:
[0001]    The present invention refers to the field of hydrocarbons extraction from oil wells and more particularly, it refers to an integral production system and to a process to extract such hydrocarbons from wells not having a high pressure gas distribution pipeline to restore original production levels. 
         [0002]    The described system is based on a pneumatic pumping system for the artificial production of oil wells. 
       BACKGROUND AND FIELD OF THE INVENTION 
       [0003]    It is already known that if the deposit static pressure is larger than the sum of all the hydrocarbon pressure drops from the bottom of the well to its processing center, then oil will flow naturally. However, if the static pressure is less than the result of the summation, some artificial production process will be required. 
         [0004]    The present invention refers to the system of artificial production which, as above mentioned, is used when the oilfield energy or pressure is not enough to lift fluids (oil-gas mixes) up to the surface for human use. In general, the artificial systems are classified into three big branches: Systems by mechanical pumping, systems by pneumatic pumping and electrocentrifugal systems. 
         [0005]    Pneumatic pumping consists on injecting a gas at a relatively-high pressure where the injected gas moves fluids to the surface for pressure reduction exerted by the fluid, the injected gas expansion or fluid displacement. 
         [0006]    The pneumatic pumping is flexible, both in its configurations as in the capacity it controls, is able to manage sand within the well, need not much space for the facilities in surface and with a single system several wells can be fed and additionally, no modifications are required in the well completion for any type of variations as it actually happens in the mechanical, electrocentrifugal pumping and progressive cavity. 
         [0007]    The present invention relates to the field of pneumatic pumping with the patentable characteristic to be easily portable and be adapted to the available space in wells. 
         [0008]    Following patent applications and registered patents related with the present invention are known. 
         [0009]    The U.S. Pat. No. 3,215,087 provides a new and improved system of artificial lift by gas. In accordance with that described by said patent, it was found that lift efficiency may be improved through the intermittent injection of a viscous and immiscible fluid with the fluid that is intended to be recovered from the well, being displaced with gas coming from the well or from an external source through the annular lining-priming, passing through a valve ( 22 ) to the inside of the priming, and not from a system of self-supplied and continuous pneumatic pumping (BNA) as in the present invention. 
         [0010]    This patent discloses that fluids used for purposes of the invention are solutions that are practically immiscible with fluids produced or extracted from the well, that do not adhere to casings, piping and another equipment with which fluids come into contact and having enough viscosity to resist cuts during flow. In the case where the fluid produced is crude oil, an aqueous solution that contains a polysaccharide, a poly-acrylamide, sulphonated aromatic poly-vinyl is used, or a thickener of soluble water or dispersible in water, in a concentration enough to produce a practically superior viscosity to the one of crude oil, which is not produced in the present invention. 
         [0011]    MX Patent 43214, entitled “Method for Producing Oil from Partially Exhausted Wells” filed on Jun. 3, 1944. It is stated that this patent is the closer state of the art and that shows the following differences regarding the present application: 
         [0012]    a) The patented process is in the field of the secondary improved recovery (EOR) while the one of the present application hereinafter called as BNA system (self-supplied pneumatic pumping) is an improvement of the pneumatic pumping as system of artificial production (SAP); 
         [0013]    b) In the patented process of vapor fractions injection recovered by means of distiller equipment and distillation columns are injected to a well for improving viscosity of the whole oilfield oil and that the rest of wells improve production through this action, positioning this invention in the oil recovery systems while in BNA (process object of the present invention). 
         [0014]    U.S. Pat. No. 4,666,377 named “Method and Lift Pump and Raising Liquids” refers to an apparatus and specifically it is related to a sub-superficial pump, submerged at approximately 50 of the fluid column contained in the well, so that it uses liquid such as motor fluid and not gas as in the present invention. Additionally, the use of auxiliary systems in this disclosure is missing. 
         [0015]    The U.S. Pat. No. 5,006,046 named “Method And Apparatus For Pumping Liquid From a Well Using Wellbore Pressurized Gas” is based on the insertion of a piping inside a well liner to extract oil from the bottom, by means of the pressurized gas injection in cyclic form and controlled by means of a sensor to measure the liquid level and a controlling valve at surface that enables gas going through to the well and push the oil to the surface. This patent remarkably differs from the present invention since it is based on a continuous operation system neither indicates the use of separation and compression by gas equipment, so that it needs an external source providing gas under pressure. 
         [0016]    U.S. Pat. No. 6,298,918, entitled “System For Lifting Petroleum By Pneumatic Pumping” involves the development of an apparatus and procedure for the application of a fluid accumulation camera inside a well and the injection in cyclic form of a gas under pressure to displace the oil to the surface so that it differs from our novelty in that, it does not use any equipment to store fluids inside the well and that this requires as specified, that gas under pressure availability must exist as external source. 
         [0017]    U.S. Pat. No. 6,354,377 entitled “Gas Displaced Chamber Lift System Having Gas Lift Assist” comprises in a modification of the previous patent and among main changes, there is the inclusion of a second liquid accumulation camera in the bottom of the well and a multi-stage motocompresor with a capacity of providing a pressure higher than 5,000 psi to inject gas to the chambers. It is not specified, but equally a source of external gas under pressure is required and the process is also cyclic differing from the present invention. 
         [0018]    U.S. Pat. No. 7,147,059 entitled “Use Of Downhole High Pressure Gas In a Gas-Lift Well And Associated Method” consists on the application of equipment and methods to isolate and use the high pressure gas zones to be used as high pressure supplying source and to be used as continuous pneumatic pumping. The difference is obvious to our application since it does not use gas associated to the production of oil, neither any of the separation and compression equipment. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0019]    The invention refers to a system that includes portable equipment for the artificial production of wells with low production that comprises at least one separating and rectification skid, at least a skid of motor compression, auxiliary equipment of energy supply and communication and control equipment, among others, each one mounted on a solid and movable structure with capacity to support weight, dimensions and pressures of integrating components, that will be named hereinafter as skid and is designed exclusively to make its mobilization easy for the required sites. 
         [0020]    The system of the present invention is designed and built for the artificial production through pneumatic pumping of oil and gas producing wells. Worth to mention is that the system does not need connection to an expensive infrastructure of dry or humid natural gas distribution network under high pressure since the gas to be injected to the well is derived thereof. 
         [0021]    The system is considered highly effective as compared with any other one that requires the use of external supplying sources as inert gases injecting units or any other such as nitrogen, which contaminate gas and oil produced causing decrease in the commercial value of the same due to physical and chemical properties loss. Another advantage is that using the same natural gas produced from the intervened well, mixture improves increasing production. So that this system is completely autonomous, independent, efficient and portable. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURE 
         [0022]    The  FIG. 1  schematically depicts and block-diagram, the main components used in the innovative and inventive process represented by means of arrows. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    The present process is an improvement of the pneumatic pumping as system of artificial production (SAP) of oil wells since it is not necessary for the user to carry out expensive investments associated to high pressure gas infrastructure to the well to intervene, neither assumes the risks associated to the productive status of the well in case it does not justify said investment caused by volumes (usually low) that are obtained in the remaining life time of the well. 
         [0024]    In a first embodiment, it refers to a process that comprises: 
         [0025]    a) The selection of the well to be exploited following the criteria of wells selection through pneumatic pumping by PhD Kermit Brown in his book Gas Lift Theory and Practics, published by Petroleum Pub. Co. and with registration ISBN 10 0878140247 of 1967; and 
         [0026]    b) Designing the system of artificial production under the technical recommendations used in industry oil. 
         [0027]    The step a) is carried out calculating, by means of that described in the book of Brown, the following parameters: 
         [0028]    Separation pressure, 
         [0029]    Injection depth, 
         [0030]    Injection pressure, 
         [0031]    Temperature of oil and gas in surface 
         [0032]    Volume of optimal gas to inject, 
         [0033]    Production of oil, gas and water in surface. 
         [0034]    With these parameters is determined if, in principle, the well in question is adequate or not for profitable production. 
         [0035]    In case of being so, proceed to the step b) of the present invention, that consists on calculating the technical characteristics of the various skids or grouped components. 
         [0036]    The first step within the calculation of the skids is b1), calculating the technical characteristics that the separating and rectifying skid must comply, following international standards API 12J and the recommendations of the GPSA Engineering Data Book Section 7. 
         [0037]    The following step is b2), determining capacity and size of the motor compressor considering the optimal volume and pressure of gas to inject, obtained in the designing process of the system, under the API 11P standards. 
         [0038]    The auxiliary systems of energy b3) are calculated in terms of the energy requirements of the separating skid and moto-compressor skid and the various minor components such as measurement and/or reading valves and equipment. 
         [0039]    The system of the present invention (BNA) is evident, at the same location than that of the well, of:
       Skid with at least a moto-compression equipment with power combined from 35 to 1120 Kw;   Skid with at least one equipment of oil and gas separation with oil flow measurement and of gas separately;   Skid with at least one gas rectifying equipment gas; and   Auxiliary subsystems of energy supplies for the instrumentation system and electric facilities.       
 
         [0044]    One of the operation contributing factors of the BNA system is that there no supplying gas system under external pressure, since for the invention purpose and in a second embodiment thereof, the BNA system substitutes such supply for the artificial production of low-production wells. 
         [0045]    The components referred above are arranged and distributed so to occupy the minor space in order to avoid pressure drops. As known for experts in the art, piping used complies with ASME specifications 31.3. 
         [0046]    In the preferred mode of the invention, skids (separating skid and moto-compression skid) and the well are equidistantly positioned and preferably to a 30-meter distance between thereof to optimize the area of installation and decrease the pressure drops of the different products: oil-gas, oil and gas mixes. 
         [0047]    Another embodiment of the present invention is the inclusion of bombs and storage system for oil and water displacement produced at the same location considering that wells pressure may be decreased to an atmosphere and increasing with this productive life of this type of wells. 
         [0048]    Process starts with the transportation of oil-gas mixture, of the well ( 100 ) towards the separating skid ( 103 ), by means of production piping ( 101 ), which are a part of the inventive process. Already inside the skid ( 103 ) the gaseous and liquid separation of the phases is made (oil and water), transferring liquids to the center of closest processing, gas is passed by means of piping ( 104 ) to the rectifying stage inside the separating skid, during rectifying step, gas is purified from liquid particles suspended therein. After rectification, it is driven to moto-compression skid ( 110 ) to moto-compression suction inputs, through a piping that is characterized for starting in first diameter to the rectifier output to go on with a second diameter that is bigger than the first diameter and finalizing in the moto-compressor input with a third diameter that is equal or smaller to the first diameter. 
         [0049]    Gas-oil exhaust bypass valve ( 102 ) is generally kept closed during passing through oil and gas to the separator; it is only opened when there is maintenance service in the well to send the product direct to the processing center. 
         [0050]    Inside the separating skid ( 103 ), in the piping ( 104 ) that communicates the separator with the rectifier ( 106 ), at least one control valve ( 105 ) (gas excess valve) is included, in order to open and purge any exceeding or gas exceeding volume required by the BNA system design to the processing center thus avoiding a not desired increase in the separation pressure that might affect well production and moto-compressor functioning when working with a higher pressure than the one of the design. 
         [0051]    Once piping is connected to the processing center and the rectifier ( 106 ), gas excess control valve is located ( 107 ) that is a pneumatic control valve (although another type of actuator may be used) that remains closed and operates jointly with the valve ( 105 ) and opens only to send exceeding gas to the processing center. 
         [0052]    Gas passageway line ( 108 ) to regulation package leads gas to a permissible working pressure for regulation equipment, same that was obtained with the intervention of the exceeding valve ( 107 ). 
         [0053]    Gas, before reaching the moto-compressor&#39;s suction, goes by a set of regulating valves ( 109 ) which keep pressure in the conduit piping to moto-compression&#39;s skid constant ( 110 ) before any pressure variation that can occur from the separating skid ( 103 ). Already inside the compressor, the pressure of the gas to attain the pressure from injection to the well, within the design range, increases. 
         [0054]    Compression process takes effect in the compression skid ( 110 ) with at least one compressor ( 110 A) of positive displacement driven by a motor which can be an internal combustion engine or an electric motor, adjusted to the separation pressures and the motor revolutions per minute (rpm) to attain optimal volume and pressure of gas injection to maximize well production. All these processes are supported by the auxiliary energy systems ( 114 ). 
         [0055]    Gas already to the required injection pressure, gets out of the compression skid ( 110 ) towards the well ( 100 ) by at least one arrangement or distribution of valves and flow regulation ( 111 A) and purge piping ( 111 ) to access to the well by means of access valves of the well casing and to be driven through the same even until the depth of design injection, blending in with the production of oil-gas mixture inside the well priming that is associated to a hydrocarbons oilfield reducing the weight of the production column. 
         [0056]    The inclusion of bombs and a storage system ( 114 ) for oil and water displacement that are produced at the same location, considering wells pressure decrease to an atmosphere, improves the productive life of the intervening well. 
         [0057]    In order to avoid corrosion-due damage to the well casing, a flexible piping ( 113 ) or alike is included, with a smaller diameter to the priming of the well intervened, where the gas injected to the optimal injection depth is channeled, in that way to mix with the production of gas-oil mixture. 
         [0058]    A last component of the system is a measurement and control equipment of the system ( 112 ) as well as its most important components and monitoring the production of the gas-oil mixture, of the isolated oil and of the isolated gas. A remote data monitoring and collection system was implemented by means of telemetry signals to supervise and control the operations from a remote point. 
         [0059]    Another embodiment or facility the system has, is having arrangements of interconnection valves ( 115 ) to connect other movable BNA systems for maintenance to the installed equipment purposes and assuring the operational efficiency and continuous production. 
         [0060]    The process above described is implemented thanks to the interconnection between the skids and components above mentioned.