Measuring and testing – Liquid analysis or analysis of the suspension of solids in a...
Reexamination Certificate
1999-12-21
2001-10-23
Williams, Hezron (Department: 2856)
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
C073S053040, C073S061440, C073S152210, C073S152420, C073S861040, C073S200000, C702S012000
Reexamination Certificate
active
06305216
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to oil and gas wells. More particularly, the present invention relates to an improved method and apparatus for predicting the state properties of a multi-phase fluid at any point within the fluid conduit of an oil and gas well.
2. Description of the Related Art
Oil and gas have been extracted from the subsurface of the earth for many decades. Well holes are drilled into the earth until a reservoir of fluid is reached. The underground fluid is then extracted and refined for various purposes. As with most oil and gas wells, the extracted fluid is a multi-phase mixture of oil, water, and gas. The gas itself is in two forms, free gas and gas that is in solution either with the oil or with the water.
The monitoring of the production of fluid from oil and gas wells continues to be an important activity. Not only is monitoring necessary for obvious economic reasons, but also as an indicator of serious problems, such as leaks in the piping making up the well.
Currently, oilfield service companies physically insert a measuring tool into the flow conduit of a well to measure fluid characteristics such as temperature, pressure, and total flow rate. The process of physically measuring and recording the flow in a well hole is called production logging. At best, a production log may provide an accurate snapshot of production information at the particular time that the measurements are made. However, this information can change relatively quickly, especially in a well with multi-zone production where the production from one zone can affect the production in another. There are several other problems involved with prior art production logging methods. First, the measuring device that is used has a finite size, so it disturbs the flow that it is trying to measure and introduces error into the measurement and subsequent calculations. Second, the measuring device must be calibrated in the well. Unfortunately, the well cannot be producing while the measuring device is being calibrated so the calibration period results in a loss of revenue for the oil well owner. Consequently, current production logging methods are not entirely satisfactory.
There has been, therefore, a need, for a variety of methods and/or of devices for production logging that can measure accurately the production capacity of an oil and gas well without disturbing the fluid flow during measurement and more specifically, there exists a need for using two sets of stabilized surface production tests to more accurately predict the results of a well analysis. There is also a need in the art for a method that does not require the well to be shut down during calibration of the measuring instruments for this stabilized data. It is an object of the present invention to solve the problems inherent in the prior art methods and to give an accurate surface production test information. It is a further object of the present invention to utilize existing equipment on the wellhead to enable remote monitoring of well production.
SUMMARY OF THE INVENTION
The present invention solves the problems inherent in the prior art. The evaluation program of the present invention is capable of performing a series of functions necessary to calculate the characteristics of the multi-phase fluid flow along the predefined geometry of the well hole and eliminating or reducing the existence of erroneous surface production test data by providing an accurate data combination by taking data at different points in time in order to determine the existence of accurate stabilized production data for use in well analysis. Using this improvement an evaluation program divides the geometric profile into a series of discrete segments of a predefined thickness, starting at the wellhead and ending at the last reservoir. Starting at the wellhead, the evaluation program trains, segment by segment, wellhead data until the end point is reached. At the starting point, the wellhead temperature and pressure, the wellhead geometric profile, the wellhead gas production rate, and the oil, condensate and water production rates are provided. To determine the conditions at the segment just below the wellhead, the evaluation program extrapolates the temperature profile to estimate the temperature at that particular segment location. Similarly, the geometric profile is extrapolated to determine the geometric configuration of the segment at that particular location in the fluid conduit. Using the total flow rate at the previous step (in this case, at the wellhead), an estimated pressure is calculated for that particular segment. The estimated pressure, estimated temperature, estimated geometry are used to calculate an estimated total flow rate of the fluid in the well hole at that particular location. These estimated values are used to correlate the phase segregation of the fluid at any one segment, and then to act as the initial values for the next segment farther down the well hole. These steps are repeated until the end point of the well hole is reached. The improvement imposes using a pair of stabilized surface production tests to determine if a minimum point exists for the change in pressure with the change in total gas production rate for a given change in total liquid production rate between the two tests. If the minimum point exists then the pair of stabilized surface production test is accurate, if not then the pair of tests is not possible and another pair of tests should be investigated until an accurate pair of tests is found.
This method is also useful for estimating the phase segregation of the fluid in the well. Once the phase segregation can be determined at each step within the well geometry, the constituent flow rates of the gas, water, and oil can also be calculated.
These velocity rates are useful in determining if apparent flow rate losses are due to liquid drop-out (retrograde condensation) of the gas. Furthermore, apparent fluid flow losses or gains at particular steps can be attributed accurately to thief zones or production zones, respectively.
REFERENCES:
patent: 4657529 (1987-04-01), Prince et al.
patent: 4787421 (1988-11-01), Yu
patent: 5327984 (1994-07-01), Rasi
patent: 5635631 (1997-06-01), Yesudas et al.
patent: 5924048 (1999-07-01), McCormack et al.
patent: 5937362 (1999-08-01), Lindsay
patent: 5959194 (1999-09-01), Nenniger
patent: 6021664 (2000-02-01), Granato et al.
Buskop Wendy K.
Buskop Law Group PC
Production Testing Services
Wiggins David J.
Williams Hezron
LandOfFree
Method and apparatus for predicting the fluid... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for predicting the fluid..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for predicting the fluid... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2605322