Wells – Receptacles
Reexamination Certificate
1999-12-16
2001-02-06
Noland, Thomas P. (Department: 2856)
Wells
Receptacles
Reexamination Certificate
active
06182753
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a fluid sampling tool and method of use which, in response to pressure, opens to collect a fluid sample, and more particularly, to a sampling tool which provides for collection of a fluid sample without flashing of vapor in the liquid and which retains the fluid in a supercharged condition.
2. Description of the Prior Art
In general, to obtain a sample of fluid in an oil or gas well, a fluid sampling tool is first lowered into the well on a tubing string or a wireline or a slick line. When the tool is at the desired depth, a port (one or more openings) defined in the tool is opened. The port may open in response to pressure exerted through the well fluid or in response to an electrical actuation signal from the surface. The open port admits well fluid into a sample retaining chamber within the tool. The port is thereafter closed, the tool is withdrawn from a well, and the sample is taken from the chamber for analysis.
U.S. Pat. No. 4,903,765 to Zunkel, assigned to the assignee of the present invention, shows an improvement in such fluid sampling tools, wherein the fluid sampling tool is constructed to have a time delay which starts when a valve of a tool first starts to move in response to pressure from the well. This time delay provides various advantages. In one instance, the time delay allows undesired fluid such as drilling fluids to bypass the sampling tool before the valve communicates a sample port with a sample chamber and a sample of the well fluid is taken. In another instance, the time delay can reduce the dependency on accurate pressure readings and shear pins which control the opening of the valve. For example, when a maximum bottom hole pressure is measured or otherwise anticipated, shear pins providing a holding force of something less than this maximum pressure, but one which will clearly be encountered somewhere downhole despite a lack of assurance as to precisely where it will be, can be used so that the pins will break at some location above the bottom of the well. This time delay, designed with a suitable tolerance to assure reaching bottom before its expiration, is then used to allow the tool to be run on down to the well bottom, where it is ultimately automatically opened.
U.S. Pat. No. 5,058,674 to Schultz et al., also assigned to the assignee of the present invention, provides various improvements upon a delayed opening fluid sampler of the type generally shown in the Zunkel patent. These improvements relate generally to various means for controlling the actuation of the valve which controls flow of the sample fluid to the sample chamber.
A problem with some prior art fluid samplers is that the sample is obtained relatively quickly which can cause the fluid to flash (separation of the liquid and vapor stages) as it is flowing into the sampling chamber. This is an undesirable condition and can affect the quality of the fluid sample. The sampler of the present invention provides for controlled flowing of the fluid into the sample chamber which greatly reduces or eliminates fluid flashing.
Another problem with some prior fluid samplers is that when they are removed from the wellbore, the reduction in hydrostatic pressure acting on the sampler as it is raised also results in fluid pressure therein being reduced. The drop in pressure can cause phase change degradation of the sample. That is, flashing can occur as the sampler is removed from the wellbore. The sampler of the present invention solves this problem by providing for the fluid sample to be trapped at well hydrostatic pressure regardless of the pressure outside the sampler. This “supercharging” of the fluid sample greatly reduces or eliminates phase change problems.
SUMMARY OF THE INVENTION
The present invention includes a non-flashing fluid sampler used in obtaining a well fluid sample and also includes methods of sampling a well using the fluid sampler.
The fluid sampling apparatus comprises a body having a first chamber, a second chamber, a third chamber and a sampling port defined therein. The sampling port is in communication with the first chamber and with an outside zone outside the body. The apparatus may further comprise a flow restrictor, disposed in the body between the second and third chambers, for impeding fluid flow from the second chamber to the third chamber.
The apparatus may also comprise a control valve, disposed in the body between the second and third chambers, for initially isolating the second chamber from the third chamber and for placing the second chamber in communication with the third chamber when activated so that, as fluid flows from the second chamber to the third chamber, fluid from the outside zone may flow through the sampling port into the first chamber.
An activator is provided for activating the control valve. In a preferred embodiment, the body further defines a control port therein which is communicated with the control valve and a second outside zone outside the body. The activator is disposed in the control port and adapted for opening the control port and activating the control valve in response to pressure from the second outside zone. The activator may be characterized as adapted for activating the control valve when a pressure differential between the second outside zone and the control valve reaches a predetermined level. This activator may be characterized by a rupture disc disposed across the control port.
The sampling apparatus may further comprise a floating piston disposed between the first chamber and the second chamber and movable in response to fluid flow from the second chamber to the third chamber which results in fluid flow from the outside zone in communication with the sampling port into the first chamber. The floating piston preferably comprises a first piston portion and a second piston portion adjacent to the first piston portion. The first and second piston portions are relatively movable and define a variable volume therebetween. A lock is provided for locking the first and second piston portions together after predetermined relative movement therebetween. The variable volume is in communication with the sampling port and allows a portion of fluid flowing through the sampling port to flow into the variable volume before the first chamber is filled. In this way, “dirty” fluid is flowed before overall movement of the floating piston to enlarge the first chamber.
A check valve is provided in communication with the sampling port for allowing fluid flow from the sampling port into the first chamber in response to movement of the floating piston while preventing fluid flow from the first chamber outwardly through the sampling port.
The fluid sampling apparatus further comprises an isolation valve, disposed in the body, for allowing hydrostatic pressure from the well into the body, thereby communicating the hydrostatic pressure to the first, second and third chambers. Another check valve is provided for preventing fluid flow outwardly from the body and for trapping the hydrostatic pressure in the body.
A second floating piston is disposed in the body and is in communication with the third chamber and movable in response to fluid flow from the second chamber to the third chamber. The apparatus further comprises a plunger for engaging the isolation valve in response to predetermined movement of the second floating piston. In one embodiment, the plunger is adjacent to the isolation valve and movable by the second floating piston in response to the predetermined movement of the second floating piston such that the isolation valve is opened. The body further defines a fourth chamber therein, and the plunger is disposed in the fourth chamber. The fourth chamber is preferably air filled.
The plunger preferably defines a differential area thereon such that, when the hydrostatic pressure is applied to the plunger, the plunger and second floating piston are forced downwardly which raises the pressure in the first, second and third chambers of the body to a level
Halliburton Energy Service,s Inc.
Herman Paul I.
Kennedy Neal G.
Noland Thomas P.
LandOfFree
Well fluid sampling apparatus with isolation valve and check... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Well fluid sampling apparatus with isolation valve and check..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Well fluid sampling apparatus with isolation valve and check... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2611130