Embed Size (px)
Transcript of documentatie onepetro
Copyright 1999, Society of Petroleum Engineers, Inc. This paper was prepared for presentation at the 1999 SPE Mid-Continent Operations Symposium, held in Oklahoma City, Oklahoma, March 28-31, 1999. This paper was selected for presentation by an SPE Program Committee following review of information contained in an abstract submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material, as presented, does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Papers presented at SPE meetings are subject to publication review by Editorial Committees of the Society of Petroleum Engineers. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of where and by whom the paper was presented. Write Librarian, SPE, P.O. Box 833836, Richardson, TX 75083-3836, U.S.A., fax 01-972-952-9435.
Abstract This paper is a follow-on to SPE 28694 (Ref. 180) which summarizes and categorizes ESP literature by a number of different topics. The intent is to list problems mentioned in various papers and a quick mention of the solutions, which are discussed in the given references. As mentioned in the previous reference, it is also an attempt to relate problems to various field conditions, however many of the field papers do not include a complete listing of field conditions, so to be able to do this from using the literature is often not possible. Introduction The first versions of this paper were compiled and presented in April 1991 and April 1992 at the SPE Gulfcoast ESP Workshops. Additionally, the most recent version was updated and presented as SPE Paper 28694 in September 1994. This edition includes papers and technical articles found or presented since the 1994 SPE paper.
This paper contains referenced categories of problems that have been encountered in field operations and the solutions that have been found to the problems. The discussion for each problem/solution set is brief, but serves as an index to the particular reference, where more detail can be found. In past papers, the discussion has been restricted to field cases. With this edition, articles that are tutorial in nature have been included. These papers may not be in the original context of field problem and solution presentations, but in most cases they do contain good technical information, which could reduce the potential of a field problem. Also, some field operational papers were not included if they presented identical information. This study was originally intended to be a review of the field cases and a summary of various failures
and their causes as a function of the conditions present. Since the publication of the first editions of these papers and a request to include the well and field conditions, it is still the exception for a given paper to list detailed field conditions. Once again, only a few contained sufficient field condition data, which would have allowed problems and solutions to be correlated to conditions.
The number of entries is some indication of where the interest is in many of the literature presentations. The following list of subjects has the number of entries listed beside the topic: Components: Pumps (5) Seal (1) Motors 8) Cable (6) Switchboard/vsd (14) Wellhead (1) Monitoring (11) ESP Applications: Harsh conditions (11) Gas (12) Heavy oil (11) Hi-temp (4) Power (6) Coil tubing (17) Horizontal wells (2) Downhole oil/water separation (9) Subsea (19) Unique configurations (7) Optimization Design (2) Optimize operations (17) Run lives (7) Misc-overall (9) Alternative Lift Studies ESPCP (9) Misc (4) New developments (4)
The above listing shows VSDs, monitoring, problems with gas, heavy oil, and harsh conditions, use of coil tubing, downhole separation, overall optimization and use of ESPCPs are of great interest. Subsea, coil tubing, and ESPCP
ESP's: On and Offshore Problems and Solutions James F. Lea, Amoco RPM/EPTG, and John L. Bearden, Centrilift
J. F. LEA, J. L. BEARDEN SPE 52159 2
are newer areas of interest. Monitoring downhole conditions is considered more in expensive offshore installations. VSDs have been around for a long time, but interest is still high related to transients and attempts to provide smooth power. The new concept of downhole oil/water separation has been referred to frequently. Harsh conditions, gas, and heavy oil are continuing obstacles to long run lives and proper design. ESP SYSTEM COMPONENTS Pumps are the first component highlighted. Compression pumps, hardened pumps, coated stages, synthetic impellers and high volume topics are addressed in Table 1.
Previous collections of literature showed a lot of discussion on multi-chamber seals used to extend run-lives. Although this practice continues, only one paper is shown in Table 2 from the literature.
The motor remains an expensive component of the ESP system. Tutorials, starting concerns, and topics related to cooling are referenced in Table 3.
Cable and splice failures are always addressed in efforts to achieve long run lives. A new entry reference is a heater cable used to solve problems of tubulars through permafrost zones or solidification in flowlines (See Table 4 for cable information).
A schematic of a typical one well VSD application is shown in Figure 1. Although VSDs have been applied for some time, they remain an area of considerable interest. Comparisons of the various types of VSDs are made, features of individual types are compared, compatibility with other components, motor heating, use with long reach wells, harmonics, and other subjects are referenced in Table 5
Table 6 has only one entry for wellheads although entries in other sections relate to wellheads..
Monitoring of downhole conditions is more common, especially in offshore expensive wells (Table 7). Monitoring of temperature, gas content of fluids and volumetric flow rate, vibration, dielectric content of motor fluids or seal leakage, and surface features to allow data recording continue to be subjects of interest. A view of the downhole completion details is shown in Figure 2 (from Reference 41) showing some downhole instrumentation used for monitoring.
ESP Application Problems Sand, scale, asphaltenes, corrosion and other harsh conditions will continue to present users of ESP systems with application problems shown in Table 8.
New developments are still surfacing, providing the user with new options to use ESP systems in gassy wells. New tests also better define and allow predictions on the effects of free gas on ESP performance. (See Table 9 for references on using ESPs in gassy wells.)
The subject of heavy oil seems to be getting increased interest. Problems with heating, lower efficiency, wear, and general design concerns are all important in dealing with heavy oil. (See Table 10 for heavy oil concerns.)
Using ESPs in high temperature is one of the industrys
success stories in recent years (Table 11). In most applications, energy usage remains a high
operational cost item in the usage of ESPs. Work is still reported on the optimization of the equipment, both from an initial design and operating variables standpoint (Table 12).
Use of coil tubing with ESPs and in many other applications is becoming more common. ESPs can be run on conventional coiled tubing with the power cable inside or outside the CT. Some CT is manufactured with the cable as an integral part of the CT, both protecting the cable , allowing for rapid deployment and retrieval of failed equipment, and allowing for live well intervention. This possibility of reduced workover costs makes the use and potential use of CT with ESP applications a popular subject (Table 13). See Figure 3, which illustrates some options when using CT with ESPs.
A section on horizontal wells is shown in Table 14, but the use of ESPs in inclined wells is also detailed in the Subsea section and other related topics.
Downhole oil/water separation (Table 15) is a new development, initiated by CFER and made available by ESP manufacturers. A schematic of the concept of the system is shown in Figure 4.
Subsea ESP installations (Table 16) compete with multiphase flow pumps and gaslift. Quite a number of references are presented. Figure 5 (from Ref. 132) shows the layout of an offshore ESP developed field, Figure 6 (from Ref. 132) shows some downhole completion details from a subsea ESP developed field. Figure 7 (from Ref. 137) shows an extended reach ESP completion including a formation saver valve.
Various unique completions including dual ESP completions, for both redundancy and additional lift, are referenced in Table 17.
ESP Optimization Table 18 lists a few items related to design only.
Optimization efforts usually result in cost effective results. Figure 8 (from Ref. 166) shows some failure concerns and percentages of failure types before a successful optimization effort was initiated. After the study, as can be seen if the reference is studied, failure concerns were reduced in frequency and in the number of types of failures occurring (Table 19).
Data on field results and how to manipulate data for useful conclusions are discussed in the references and Table 20. Table 21 lists miscellaneous overall subjects.
Alternative Lift Studies
Although not an ESP, the ESPCP uses many o