Rate-Depth Tubing Performance Curves
- H.W. Winkler (Consultant) | P.T. Eads (Camco Products and Services)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- June 1994
- Document Type
- Journal Paper
- 119 - 123
- 1994. Society of Petroleum Engineers
- 1.6 Drilling Operations, 3.1.6 Gas Lift, 5.4.2 Gas Injection Methods, 5.2.1 Phase Behavior and PVT Measurements, 5.3.2 Multiphase Flow
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An accurate method for predicting the range of multiphase flow rates through different tubing sizes is an important production tool. Properly sized tubing will prolong the flowing life of a well and minimize the injection-gas requirements for gas-lift installations. A tubing string can be oversized or undersized. This paper presents a method for relating the four basic parameters for different tubing sizes: daily liquid production rate, tubing length or depth of gas injection, flowing production pressure at depth or surface operating injection-gas pressure, and the gas/liquid ratio (GLR). This information is displayed as rate/depth tubing-performance curves, which are based on the Shell Ros-Gray multiphase flow program. These curves allow proper tubing-size selection for a predicted range of daily production rates.
A reasonably accurate method for predicting multiphase flow rates through different tubing sizes is an important production tool. Properly sized tubing will prolong the flowing life of a well and minimize injection-gas requirements for gas-lift installations. A well may cease to flow or have severe heading with oversized tubing or may have restricted production with undersized tubing. Our method relates the four basic parameters for different tubing sizes (daily production rate; tubing length or depth of gas injection; flowing production pressure at depth, ppfD, or surface operating injection-gas pressure, pio; and GLR) and displays this information as rate/depth tubing-performance curves.
These curves allow selection of proper tubing size for a predicted range of daily production rates and illustrate the decrease in liquid production as required depth of lift increases. The error in selecting an arbitrary optimum injection GLR (IGLR) for a group of gas-lift wells with different deliverability characteristics in the same system is apparent from the curves.
The reported accuracy (± 10%) between computer programs based on different multiphase flow correlations in terms of actual vs. calculated flowing pressures at depth is debatable. Companies modify in-house multiphase flow programs (e.g., by adding flow regimes to the Hagedorn and Brown correlation). These modifications in the computer programs result in different predicted ppfD than in programs based on the original correlation. The range of error can be influenced by the database used to compare the correlations. The empirical equations for the fluid properties and the manner in which the program code is written also affect calculated multiphase flow program results. A true measure of error is a comparison between measured and calculated ppfD from accurate production-test data.
|File Size||790 KB||Number of Pages||5|