宝马i3和i8的驱动电机技术创新
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[摘要]宝马公司为宝马i3和宝马i8配备了具有自主知识产权的eDrive混合式同步电动机，该电动机具有永磁电动机和磁阻电动机优点。宝马公司在这方面取得的进步似乎表明宝马公司找到了一个利
宝马公司为宝马i3和宝马i8配备了具有自主知识产权的eDrive混合式同步电动机，该电动机具有永磁电动机和磁阻电动机优点。宝马公司在这方面取得的进步似乎表明宝马公司找到了一个利用含有较少稀土材料的磁体来制造高功率密度和高效率电动机的方法。
　　下图为宝马公司2012年专利申请文件中的图纸，该图纸显示一种能提高电动机效率的方法&&在电动机内，转子除了磁层，还有两组由数个充气转子凹坑组成的磁通感应组。宝马公司专利申请文件N&。点击此处看大图。
　　宝马i3汽车配置的驱动电动机重50千克，最大输出功率为125千瓦，功率系数为2.5千瓦/千克;该电动机能输出线性功率，转速范围较高，其最高转速为11400转/分。如果将日产Leaf与宝马i3进行比较：日产公司在2011年生产的&Leaf&电动汽车配备的是永磁电动机，其重量为58千克，额定输出功率为80千瓦，功率系数为1.38千瓦/千克。
　　背景：虽然对电动汽车而言，改善电池性能是降低电动汽车成本和提高运输效率的主要方法;但改善电动汽车的驱动装置(电动机、动力电子设备、传动机构、热量管理)也能起到非常好的效果。
　　例如，为了集中力量研发先进的动力电子设备、电动机、热量管理和传动机构技术，美国能源部汽车技术办公室制定了&先进动力电站设备和电动机&计划;一旦该计划取得成功，其先进性是现在技术所无法比拟的。动力电子设备和电动机作为电动汽车驱动系统的子系统，其重量、体积、效率和成本要严格要求，为了成功地研发出这些设备，使用更高功率密度和更低成本的小型电动机是关键。
　　能匹配到电动汽车上的电动机多种多样，包括直流电动机、交流电动机、感应电动机、永磁电动机、开关磁阻电动机和轴向磁通电动机。除了Tesla和丰田，其他所有主要汽车生产厂商制造的电动汽车均配备直流电动机。Tesla Model S配备交流电动机(据说Tesla Roadster也使用交流电动机)，而丰田的电动汽车传动系统就是采用Tesla公司的设计。值得注意的是，宝马在其Mini-E电动汽车项目的首次试验中，宝马也让试验中的Mini-E成为了交流电动机驱动的汽车。
　　广义地说来，一个感应电动机就是向电动机的固定外定子线圈输入交流电流，在定子线圈内形成一个旋转磁场，转子绕组受该旋转磁场的感应而产生电流，随着转子绕组电流的产生，转子绕组磁场也随之产生，转子绕组的磁场受到定子磁场的吸引。简而言之，转子的感应电流和随之产生的磁场被定子线圈磁场所吸引，由此让定子旋转并产生扭矩。由此可见，交流感应电动机无需永磁磁铁零件便能让转子转动。
　　总体而言，感应电动机的优势就是能被大规模生产和使用，但感应电动机不能满足美国《关于汽车效率和能源可持续性的驾驶技术研究和创新》的在成本、重量、体积和效率方面的要求。
　　另一方面，永磁电动机将永磁体装入到或嵌入转子，其磁场与通电产生的定子线圈内磁场相对应。永磁电动机具有紧凑结构和高扭矩密度输出的特点，并且能以较低电流来启动。虽然如此，永磁体材料的成本是一个有待解决的问题，因为电动机旋转产生的热量有可能对永磁体产生损害。
　　开关磁阻电动机结构简单，动力充沛，看起来是一个成本最低的技术解决方案。但开关磁阻电动机有不少缺点，如转矩波动高，噪音大、功率因数低和效率低。
　　因此，研究人员一直致力于设计新型电动机，他们的研究方法有减少永磁体的载荷，使用多种材料来制造电动机，以及综合各种电动机的技术优点来设计混合式电动机。2012年出版的《电气工程和技术杂志》就刊发了一篇论文，该论文专门对混合式电动机结构进行了分析。下面是该文章的一部分：
　　随着技术的进步，人们在工业领域对具备多种技术特征的电动机的需求越来越多。因此，关于改进电动机的研究论文能在各种各样的文献中见到。依据这些文文献资料的记载，新型电动机已被研制出来，对现存的各种电动机的研究也是铺天盖地。
　　在各种论文中，永磁电动机和磁阻电动机是最热门的研究对象。研究人员已经探讨了各种结构的永磁电动机和磁阻电动机，并对此进行了试验。值得注意的是，随着永磁材料的性能的提高，研究人员开发新型永磁电动机的热情日益高涨。永磁电动机的类型可分为永磁同步电动机和无刷直流电动机。在基本速率的条件下，永磁电动机的性能十分不错，但永磁电动机的变速范围十分小。
　　磁阻电动机没有永磁体零部件，让它没有退磁风险，并能在高温环境中正常工作。磁阻电动机的工作原理是基于磁阻原理，人们将其分为两大类：开关磁阻电动机和同步磁阻电动机。
　　永磁辅助磁阻电动机是研究人员为了综合永磁电动机和磁阻电动机的优点而研发到新型电动机。永磁辅助磁阻电动机被认为具有高功率密度、高功率因数、高效率和变速范围广的技术优点，现在永磁电动机已经成为了十分引人注目的话题。永磁辅助电动机的扭矩由永磁磁场和磁阻效应共同产生，研究人员因此将永磁辅助电动机称为混合式电动机。研究人员为永磁辅助磁阻电动机转子设计了多种结构，目的就是为了产生合适的磁场和磁阻效应扭矩。
　　宝马的研发方式
　　宝马注意到由于电动汽车的空间有限，电动汽车使用的电动机必须是功率输出高、扭矩大和重量轻;电动汽车的传动系统的效率直接影响着电动汽车时行驶里程。因为高电压电池价格昂贵，提高电池电量的利用率就成为了获取电动汽车最大行驶里程的重要因素。
　　永磁电动机能产生磁阻转矩和永磁转矩。宝马的2012年专利申请文件中有以下说明：永磁同步电动机能在多个磁体方向中(即不同的磁极方向中)产生一系列不同的电磁感应和与磁极方向相反的交叉电感;只要驱动电动机以合适的方式驱动，电动机就能产生磁阻转矩。这种磁阻转矩能对电动机永磁磁通产生的转矩相互补充。
　　简单地说来，宝马使用的电动机可归类为永磁同步电动机，但宝马对该电动机进行了精心的设计，并选择合适尺寸的零部件来制造，让其能产生自磁化效应;该自磁化效应原本只有磁阻电动机才能产生。自磁化效应带来的额外励磁效果能为电动机电流励磁提供有益的补充;在高速旋转时，两种励磁方式让其工作更加可靠。宝马i3使用的电动机的最高转速能达到11400转/分。
　　从前文的描述中，我们已经知道驱动电动机定子内的电流在磁场削弱的范围中起到了实质性电流分量地作用。定子内电流产生的磁场与永磁体的磁场相互排斥。虽然这样，但按照物理原理，永磁体材料的通量密度是不会衰减的，此磁通将被定子的磁场所排斥。定子和转子之间的气隙为转子铁芯磁通通道的形成提供了条件。
　　定子电流产生的磁通在定子和转子间沿着磁通通道循环流动，磁通通道又被称为磁口袋，存在着一个瓶口。这种瓶口现象将导致定子齿部的磁通通量密度变化，由此将进一步导致磁通密度的变化频率超过驱动电动机的频率。上述现象将导致较高的铁芯损耗，电动机的效率也将大幅度降低。在磁场削弱范围内，这种状况尤为明显，因此电动机必须按照其运行特性进行优化。
　　为了减少定子和转子间的磁通通量瓶口现象产生的损害，提高磁通通量的稳定性是一个被广泛接受的解决方法。而为了提高磁通通量的均衡性，只能增加磁层的数量。但增加磁层数量的方法却不实际&&为了适应电动汽车的有限空间，磁层必须做得非常薄;但太薄的磁层在安装到电动机的凹槽里的过程中，极有可能被损坏，而且将让生产成本大幅上涨。
　　译注：本文中提到的磁层通常使用矽钢片制造，太薄的矽钢片，市场上很难买到，价格较高，而且在冲压过程中也很容易被折断或变形。这是我的工作经验。
　　宝马申请专利的目的就是制造一种用于电动汽车的驱动电动机;在磁场衰减范围内，该电动机的效率要好于其他电动机。这种电动机由一个定子和一个转子构成，至少有一个极对;该电动机的每个极对至少由一个内嵌磁层组成。按照宝马公司的专利申请文件的说明，该电动机的每个磁极都由多个充气转子凹坑形成的磁通感应组构成，这种磁极不会让每个磁层的磁场产生通量电导。
　　有了磁通感应组，研究人员可以一种简单而经济的方式让转子铁芯在气隙内形成的磁阻变得均匀一致。通过多个磁通感应组所产生的效应，研究人员可以抑制或最小化定子齿部磁通密度的变化。研究人员发现这种方法能大幅度地降低铁芯损耗，至少在磁场衰减范围内能达到此目的。这种方法通过压制驱动电动机定子和转子间的磁场通量流动来实现抑制定子齿部磁通密度的变化。
　　美国专利申请号：N&
　　在专利申请文件中，宝马指出上述方法适用于多种驱动电动机;同时此方法也能降低生产成本，转子的凹槽能在冲压过程中一次性加工出来。
　　宝马还提到此方法能提高电动机在高速旋转时的效率，在使用当前同等电量电池的情况下，配置了宝马新型电动机的电动汽车能行驶更远的里程。
　　从另一方面来讲，即使电池电量下降，配置了宝马新型电动机的电动汽车的行驶里程还能达到原来的技术要求。因此，通过使用新型电动机，电动汽车的成本也能降下来&&众所周知，而且在电动汽车的价格构成中，电池的成本占据了一大部分，使用小容量电池的电动汽车的成本比使用大容量电池的电动汽车将便宜不少。
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　&&&&&&京ICP备号专利 WOA1 - Dispositif et procédé permettant de transférer des objets en direction et en ... -
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(2) , Dispositif et procédé permettant de transférer des objets en direction et en provenance d'une zone d'installation sans personnelWO
A1 L'invention concerne un dispositif (1) permettant de transférer des objets en direction et en provenance d'une zone d'installation sans personnel (A), le dispositif de transfert (1) comportant un cadre (14) formé d'au moins une ouverture (15) sur un c?té orienté vers l'extérieur dans la direction de la zone d'installation sans personnel (A), et une ouverture (16) sur un c?té orienté vers l'extérieur dans la direction d'une zone (B) adjacente à la zone d'installation sans personnel (A); et au moins une section de stockage (12) contenue dans le cadre (14) et passant dans celui-ci, le dispositif de transfert (1) étant caractérisé en ce qu'il comporte au moins un dispositif de positionnement (13). Par ailleurs, l'invention concerne un procédé permettant de transférer des objets en direction et en provenance d'une zone d'installation sans personnel (A) au moyen d'un dispositif de transfert (1). Enfin, l'invention concerne aussi une utilisation d'un dispositif de transfert (1) permettant de transférer des objets en direction et en provenance d'une zone d'installation sans personnel (A).
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(1) , , Check valveUS
The present invention provides a check valve comprising a valve housing (1,2), a substantially circular flapper (3), a valve seat (16) for the flapper (3), an expandable chamber (11) in fluid contact with a connecting port (8) for hydraulics fluid, and a piston (4) having a first and a second end, the flapper comprises a first (19) and a second (18) connection point and is pivotably connected at the first connection point (19), said flapper is capable of pivoting between a closed position in close contact with the valve seat (16) and an open position which allows fluid to flow through the valve, the piston (4) is in contact with the expandable chamber (11) and a pre-stressed compressible device (15), said piston (4) pivotably connected at the first end to the flapper (3) via the second connection point and that the second connection point (18) is situated closer to the center of the circular part of the flapper than the first connection point (19).
The invention claimed is:
1. A check valve comprising a valve housing, a substantially circular flapper, a valve seat for the flapper, an expandable chamber in fluid contact with a connecting port for hydraulics fluid, and a piston having a first and a second end, wherein the flapper comprises a first and a second connection point and is pivotally connected at the first connection point, said flapper being capable of pivoting between a closed position in close contact with the valve seat and an open position which allows fluid to flow through the valve, and wherein the piston is in contact with the expandable chamber and a pre-stressed compressible device, said piston being pivotally connected at the first end to the flapper via the second connection point, characterized in that the compressible device can move the piston in a direction towards the valve seat, that hydraulic fluid can move the piston in a direction away from the valve seat when sufficient hydraulic fluid is supplied through the connection port to expand the chamber, and that the second connection point is situated closer to the center of the circular part of the flapper than the first connection point, such that the flapper comes into close contact with the valve seat when the piston is moved in a direction towards said valve seat and the flapper will pivot around the first connection point in a direction towards the piston when the piston is moved in a direction away from the valve seat.
2. A check valve according to claim 1, wherein the piston is pivotally connected to the flapper by an arm, said arm being pivotally connected to the second connection point of the flapper.
3. A check valve according to claim 1, wherein the compressible device is a spring or a gas-filled chamber.
4. A check valve according to claim 1, wherein a section of a side wall of the piston is a part of the expandable chamber.
5. A check valve according to claim 1, wherein the valve seat is interchangeable.
6. A check valve according to claim 1, wherein the flapper is pivotally connected at the first connection point by a continuous shaft.
7. A check valve according to claim 1, wherein the valve housing comprises a first and a second element connected together, each element comprising two ends wherein one end has a function suitable for joining the two elements together, said function preferably comprising threads, and the second ends of the elements comprising a flange.
8. A check valve according to claim 7, wherein the compressible device is a spring which is received in a bore that extends in one of said elements into the flange thereof.
9. A check valve according to claim 3, wherein the piston is pivotally connected to the flapper by an arm, said arm being pivotally connected to the second connection point of the flapper.
10. A check valve according to claim 2, wherein the compressible device is a spring or a gas-filled chamber.
11. A check valve according to claim 2, wherein a section of a side wall of the piston is a part of the expandable chamber.
12. A check valve according to claim 2, wherein the valve seat is interchangeable.
13. A check valve according to claim 2, wherein the flapper is pivotally connected at the first connection point by a continuous shaft.
14. A check valve according to claim 2, wherein the valve housing comprises a first and a second element connected together, each element comprising two ends wherein one end has a function suitable for joining the two elements together, said function preferably comprising threads, and the second ends of the elements comprising a flange.
15. A check valve according to claim 14, wherein the compressible device is a spring which is received in a bore that extends in one of said elements into the flange thereof.
16. A system comprising: valve,
a hydraulically over and
a cementing unit on a surface test tree,
wherein the hydraulically overrideable check valve is situated in between the flow valve and the cementing unit, and
wherein the hydraulically overrideable check valve comprises a valve housing, a substantially circular flapper, a valve seat for the flapper, an expandable chamber in fluid contact with a connecting port for hydraulics fluid, and a piston having a first and a second end, wherein the flapper comprises a first and a second connection point and is pivotally connected at the first connection point, said flapper being capable of pivoting between a closed position in close contact with the valve seat and an open position which allows fluid to flow through the valve, and wherein the piston is in contact with the expandable chamber and a pre-stressed compressible device, said piston being pivotally connected at the first end to the flapper via the second connection point, characterized in that the compressible device can move the piston in a direction towards the valve seat, that hydraulic fluid can move the piston in a direction away from the valve seat when sufficient hydraulic fluid is supplied through the connection port to expand the chamber, and that the second connection point is situated closer to the center of the circular part of the flapper than the first connection point, such that the flapper comes into close contact with the valve seat when the piston is moved in a direction towards said valve seat and the flapper will pivot around the first connection point in a direction towards the piston when the piston is moved in a direction away from the valve seat.
17. The system according to claim 16, wherein the piston is pivotally connected to the flapper by an arm, said arm being pivotally connected to the second connection point of the flapper.
CROSS-REFERENCE TO RELATED APPLICATIONS This application is a U.S. national stage of International Patent Application No. PCT/NO, filed Jan. 25, 2012 which claims priority to Norwegian Patent Application No. , filed Jan. 25, 2011, the contents of which are incorporated herein by reference in its entirety.
TECHNICAL FIELD The present invention concerns a check valve which is remotely controlled by hydraulics, the use of such in well testing, and a method for the testing of test tubing strings by use of said check valve.
BACKGROUND OF THE INVENTION According to the Norsok-requirements (D-SR-007), which are set in connection with well testing, it is required to have a check valve installed in between the kill valve on the surface test tree and the cement unit of the rig.
The reason for the requirement of a check if the well has to be killed during the test-operation, the kill valve on the surface test tree must be opened so that well-killing mud can be pumped from the cement unit through the kill valve and down into the well. The moment the kill valve is opened, said check valve will prevent hydrocarbons from flowing down towards the cement unit. It is extremely dangerous to get hydrocarbons, in the form of gas, into a cement unit.
Said check valve, commonly a flapper valve, has until now had a manual mechanical override function. A threaded steel rod is screwed into the valve housing and pushes the flapper off the valve seat and leaves a passage through which the fluid can be pumped or bled off.
The override function is necessary to allow for pressure testing, and accompanying bleeding of the test tube string, according to programs and procedures for testing of wells.
When the test tubing string has been verified as being good, the following operation is to perforate the well and to subsequently flow hydrocarbons to the surface.
However, before the test tubing string is set under pressure, the manual mechanical override function must be disengaged so that the check valve is operating as intended, in other words preventing back flow from the test tubing string to the cement unit. Disengagement of the override function is obtained by screwing the above mentioned steel rod out of position and off the flapper element, thereby allowing the flapper to seal against the valve seat.
The check valve is barrier number two, after the kill valve, on the surface test tree, i.e. the check valve shall function as a barrier against the cement unit in the case of the kill valve not being able to keep itself sealed, see the explanation above. Thus, from this point in the operation program, the mechanical override function is not to be in operation.
In order to disengage this mechanical override function, personnel must move up in the ride belt and manually disengage the function by using a threaded rod and a wrench.
Thus, this operation requires personnel to walk in the ride belt and to work within the so-called defined red zone. In principle one is not allowed to plan for operations in the red zone. However, at the present it is not possible to avoid this operation. Accordingly, such operations require an internal deviation from standard every time it is to be performed. It is always a risk of falling objects when work is performed in the ride belt, and if the sea in addition is rough it is a dangerous operation. It requires approximately 30 minutes of operational time each time the override function of this check valve is to be disengaged or engaged.
As described, the present solution for a check valve in the surface test tree leads to an increased risk for the operational personnel who are required to move around in the ride belt in order to disengage or engage the override function of the check valve. In addition, such a manual function leads to a l approximately 30 minutes each time the override function is disengaged or engaged. In this time period other operations must be set on hold while personnel are present in the red zone.
A further problem with the present check valves is leakage through the check valve when there is zero or low pressure on the well side.
Thus, in the presently known technique there exists a pressing need for a solution which can both reduce the risk towards operation personnel, and shorten the operational time, in connection with the disengagement and engagement of the override function of the check valve installed in between the kill valve and the cement unit of a surface test tree. In addition, it is desirable to minimize or remove leakage in connection with zero or low pressure on the well side of the valve.
At the present there are no check valves having a hydraulic override and which are suitable for the use described above. In the literature, a number of check valves for use in for example drill strings are described. However, these valves do not fulfill the necessary requirements concerning size (short length) and adequate sealing of the valve at low/zero pressure on the well side. Common features of check valves suitable for use in drill strings are that they do not have any restrictions regarding their length, and that they are designed primarily to be in an open position.
EP 0985798 describes a check valve suitable for use in a drill string. This valve is intended to be open during a normal operation, and is being closed in the case of for instance a blowout. In order to obtain a proper sealing, the valve is dependent on an adequate amount of excess pressure on the well side to push the flapper against the valve seat. The design of the power transfer from the hydraulic/spring-system is not suited to provide an even and sufficiently high pressure on the flapper such that the valve is tightly closed without the help of excess pressure on the well side. Further, said hydraulic/spring-system is not suited to fulfill the requirements of a maximum length of the valve if it were to be used on for instance a surface test tree.
U.S. Pat. No. 2,780,290 describes a check valve suited for use in a drill string. This valve is intended to be open during normal operations, and is closed in the case of for instance a blowout. The valve is not suited to fulfill the requirement of a maximum length if it were to be used on for instance a surface test tree.
SUMMARY OF THE INVENTION The present invention provides a hydraulically overrideable check valve especially suited for application on the kill side of a surface test tree, the use of a hydraulically overrideable check valve on the kill side of a test tree and a method for pressure testing a well testing string. The invention is further defined by the following:
A check valve comprising a valve housing, a substantially circular flapper, a valve seat for the flapper, an expandable chamber in fluid contact with a connecting port for hydraulics fluid, and a piston, the flapper comprises a first and a second connection point and is pivotably connected at the first connection point and capable of pivoting between a closed position in close contact with the valve seat and an open position which allows fluid to flow through the valve, the piston is in contact with the chamber and a prestressed compressible device such that the compressible device pushes the piston in a direction towards the valve seat, and the hydraulic fluid pushes the piston in a direction away from the valve seat when sufficient hydraulics fluid is supplied through the connection port, at one end the piston is pivotably connected to the flapper via the second connection point, the second connection point is situated closer than the first connection point to the center of the circular part of the flapper, such that the flapper comes into close contact with the valve seat when the piston is pushed in a direction towards said valve seat, and the flapper will pivot around the first connection point in a direction towards the piston when the piston is pushed in a direction away from the valve seat.
In one embodiment, the piston is pivotably connected to the flapper by an arm, said arm is pivotably connected to the flapper at the second connection point.
In one embodiment, the compressible device is a spring or a gas-filled chamber.
In one embodiment, a section of the side wall of the piston constitutes a part of the expandable chamber.
In one embodiment, the valve seat is exchangeable.
In one embodiment, the flapper is pivotably connected at the first connection point by a shaft.
In one embodiment, the valve housing comprises a first and a second element connected together, each element comprises two ends wherein one of these two ends has a function suitable for joining the two elements together, said function is preferably threads, and the second ends of the elements comprise a flange.
The check valve may also comprise a hollow cylinder which can be guided through the valve with the intention of protecting the flapper, joints and piston, i.e. the mechanism inside the valve. This will first of all be relevant when the valve is used in gravel packing operations.
In one aspect of the invention a hydraulically overrideable check valve is used in between a flow valve and a cementing unit on a surface test tree. A check valve according to the present invention is a preferred valve for such use.
Another aspect of the invention concerns a method for pressure testing of a well testing string, comprising the following steps:
overriding a check valve (7 a), installed in between a flow valve (4 a) and a cementing unit (8 a) on a surface test tree, by providing hydraulic pressure to said check valve (7 a) through a hydraulic tubing (9 a); pressure testing the and disengaging the override of the check valve (7 a) by removing the hydraulic pressure.
At the second ends of the valve housing elements, a flange may be present, but other connection devices may also be used. By using connection devices other than flanges, the valve may be used in various applications. By designing the valve with “Weco”-couplings it may for instance be used in single operations offshore or on land-based assignments. In these cases, it will be used as a safety valve.
The check valve according to the invention may also replace a so-called “Surface Safety”-valve which presently is used during well testing. It is a valve which shall prevent back-flow from the processing plant in the event that a flexible production tubing ruptures on the rig floor. In such a case, the valve will be connected to an electronic shut-down system. A signal from this system will release the hydraulic pressure of the control-line and allow the flapper to close. A risk assessment indicates that this novel valve is better suited than the presently used seat/sleave valves (Gate and Seat). The advantage of using this novel flapper valve is that no pressure is kept in between the surface test tree and the well head control manifold. Present valves close up this pressure which leads to the valves having to open with a very high differential pressure. This causes a high degree of wear on the valve with danger of subsequent leakage and down-time. It also causes a high risk of hydrate formation, which in turn is highly dangerous.
The valve according to the present invention may also be constructed in exotic material such that it may be installed on well heads situated on the sea bed.
SHORT DESCRIPTION OF THE DRAWINGS
FIG. 1: shows a typical surface test tree with a manually operated check valve on the kill side.
FIG. 2: shows an isometric drawing of a check valve according to the invention.
FIG. 3: shows a cross section of the check valve in FIG. 2, with the flapper in a closed position.
FIG. 4: shows a cross section of the check valve in FIG. 2, with the flapper in an open position.
FIG. 5: shows section C-C in FIG. 3.
FIG. 6: shows section D-D in FIG. 3.
FIG. 7: shows a magnified section of the override mechanism of the check valve shown in FIGS. 3 and 4.
FIG. 8: shows a flow chart for a surface test tree.
DETAILED DESCRIPTION OF THE INVENTION A surface test tree is used in the testing of oil and gas wells. FIG. 1 shows a typical test tree for installation on a well head. The test tree comprises a production or flow side A and a kill side B. On the kill side, a check valve 11 a is installed in between the flow valve 4 a and a cementing unit 8 a for pumping kill fluid. In order to override the check valves which are presently in use, for instance in connection with pressure testing of a well testing string, a person must move up into the ride belt and do this by the help of a manual override mechanism. To avoid this time demanding and costly operation, the present invention provides a novel hydraulically overrideable check valve, the use of hydraulically overrideable check valves in the operation described above, and a method for overriding a check valve.
In FIG. 2, an embodiment of a check valve according to the present invention is shown from the side. The valve housing comprises two separate elements, male-flange 1 and female-flange 2. In this embodiment, the elements 1 and 2 are mounted together by using 8×8 Stub Acme threads with sealing by an O-ring. A locking screw 10 (type M10) is used to prevent the elements 1 and 2 from moving during operation, the elements are thereby locked against each other. This method of coupling the elements together simplifies the maintenance since the valve does not require machine assisted high torque tightening. Male-flange 1 is the inflow section of the valve, and the fluid flow will normally arrive from this side of the valve. Embodiments having a reverse configuration, wherein the inflow section is designed as a female-flange is also possible.
The kill tubing of the rig is coupled to the inflow section of the valve, such that the fluid passes through the flapper 3, FIG. 3, as planned without hydraulic pressure being provided via a control line coupled to the connection point/port 8 ( 1/4 ″ BSP).
The male-flange 1 also comprises a valve seat 16. In this particular embodiment, a releasable seat inset is chosen to facilitate future maintenance, and to reduce maintenance expenses. Further, there is an O-ring sealing 17 in between the valve seat 16 and male-flange 1. This O-ring is a point of leakage if it should fail. However, the leakage would be internal and will not affect outer conditions or the mode of operation. The contact surface of the male-flange 1, the site where the O-ring seals, may preferably be coated by Inconell. This reduces the danger of corrosion and pittings caused by corrosive well fluid or chemicals.
The female-flange 2 is the second main element from which the valve is constructed, FIG. 3. This element contains a flapper 3, right flapper box 7 and left flapper box 12. The flapper boxes 7 and 12 forms the box in which the flapper 3 operates. The flapper 3 is coupled via an arm 5 to the piston 4. A pre-stressed spring 15 is situated in the rear of, and in contact with, the upper part of the piston 4. There is a recess below the pistons upper section, in between the piston and the valve housing. The recess forms part of a chamber 11 which expands when provided with hydraulic pressure. A gasket box 6 forms a seal between the well fluid and the hydraulically supplied fluid. In this embodiment, an exchangeable gasket box 6 is chosen to simplify future maintenance and reduce the cost of said maintenance. The lower part of the piston 4 is pivotably connected together with one end of the arm 5. The second end of the arm 5 is pivotably connected to the flapper 3 at the connection point 18. In this example, the flapper comprises a flapper arm having two connection points 18, 19 which is used for the coupling of the flapper to the arm 5 and the shaft 13.
Addition of hydraulic pressure from a separate control panel is done through a
1/4 ″ BSP connection point/port 8.
When hydraulic fluid is supplied via connection point/port 8, the piston 4 is driven backwards towards the pre-stressing spring 15 and compresses said spring. Added hydraulic fluid pressure exceeds the pre-stress force of the spring 15. When said pressurizing is performed, the flapper 3 is moved from the normally closed position, FIG. 3, to a hydraulically kept open position, FIG. 4. That is, the piston 4 pulls, via arm 5, the flapper 3 up and into an open position. This position is kept as long as hydraulic pressure is supplied.
The pressure-equalizing channel 9 ( 1/8 ″ BSP) ensures that the same pressure is maintained in the spring housing as in the front of gasket box 6. This pressure equalizing is required to maintain the functionality of the valve.
When the hydraulic pressure is released, the pre-stressing spring expands 15 and drives the hydraulic fluid out of the valve via connection point/port 8 and back to the control panel. When the expanding pre-stressing spring 15 drives the piston 4 back, arm 5 is moved and pushes the flapper 3 onto the valve seat 16.
The flapper 3 is pushed against the valve seat 16 by the pre-stressing spring 15 using a force of approximately 10 kilos.
In this manner a complete sealing against the vale seat 16 is achieved without requiring that the flapper 3 needs to be “set/helped” onto the valve seat 16 by the help of fluid pressure from the well. This prevents leakage through the check valve in the event of low pressure on the well side. The location of the connection point 18 close to the center of the flapper assists in achieving a uniform pressure on the flapper and thus an improved sealing against the valve seat 16.
The flapper 3 itself is supported by a shaft bolt 13 going through the flapper, se FIGS. 5 and 6. O-rings seal around the shaft bolt 13, in addition to two
1/4 ″ BSP seal plugs.
FIG. 7 shows a magnified cross section of the hydraulic override mechanism.
FIG. 8 shows a flow chart of a surface test tree, wherein a hydraulically overrideable check valve 7 a is installed in between a flow valve 4 a on the kill side of the test tree and the cementing unit of the rig 8 a. Further, the flow chart shows a flow valve 6 a on the production/flow side, upper 3 a and lower 2 a well valve, crown valve 5 a, well testing string 1 a, hydraulic tubing 9 a and a control panel 10 a for controlling the hydraulics. The present invention provides a method for the verification of a well testing string comprising the following steps:
Overriding a check valve 7 a, installed in between a flow valve 4 a and a cementing unit 8 a on a surface test tree, by providing hydraulic pressure to said check valve 4 a through a hydraulic tubing 9 a.
Pressure testing the and Disengaging the override of the check valve 7 a by removing the hydraulic pressure.
By using the above mentioned method according to the present invention, the operation time can be reduced from 30 min. to at most 3-4 min. It should also be noted that the check valve 7 a in this case can be managed/used in parallel with other types of operations, i.e. rig time is no longer used. The financial consequences of such a method will be in the range of 125000, -to 165000, -NOK each time the check valve is used.
Pan American Production CompanSurface controlled subsurface tubing pressure shut-off valve *Otis Engineering CorporationWell safety valveDouble E, Inc.Wellhead with safety valve for pumping well *Halliburton Energy Services, Inc.Flapper valve with biasing flapper closure assembly *Arizmendi Jr NapoleonBlapper valve tools and related methods *Camco, IncorporatedHydraulic actuating means for subsurface safety valveHalliburton Energy Services, Inc.Apparatus for opening and closing a flapper valve1International Preliminary Report on Patentability mailed Mar. 4, 2013 which issued in corresponding International Patent Application No. PCT/NO (5 pages).2International Preliminary Report on Patentability mailed Oct. 19, 2013 which issued in corresponding International Patent Application No. PCT/NO (2 pages).3Norwegian Search Report mailed Aug. 19, 2011 which issued in corresponding Norwegian Patent Application No.
pages). 米国特許分類,
国際特許分類 共通分類, , , ASAssignmentOwner name: TS INNOVATION AS, NORWAYEffective date: Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SOLTVEDT, TERJE MORTEN;REEL/FRAME:7回転データ提供: IFI CLAIMS Patent Services&2012 Google}