INTEROFFICE MEMORANDUM

BY: IRA G. ROBERTS

ENGINEER

CHEVRON USA

DATE: OCTOBER , 1995

Rod Pumping and Proppant flowback at the Lost Hills Field

SUMMARY:

Proppant flowback from hydraulically fractured wells can lead to sand wear on the pump barrel and plunger and increased pulling costs on rod pumped wells. When down hole filters were utilized, run life of the pumps with the filters increased 135%. Well pulling cost savings of $9.24 were documented for filters. Application guidelines based on the sand loading rate and gross liquid production of the wells are presented as well as some operational experiences.

DOWN HOLE FILTERS:

These filters come in different sizes, models and modes of installation. The two modes of installation are pump run and tubing run. Pump run filters screw into the bottom of the pump and are run with the pump. Tubing run filters have been screwed onto the bottom of the tubing string and can only be cleaned or refurbished by pulling the tubing.

The two different filter models are cartridge type and disposable type. Cartridge types have replaceable elements and a perforated pipe housing. The elements come in six foot lengths and the length of the filter can be modified by stacking elements. The disposable type has a 30-foot element that is housed in a slotted fiberglass pipe. The length of these filters can only be modified in 30-foot increments by attaching one on the bottom of the other. The most common filter types in use at Lost Hills are 1" pump run cartridges (lengths typically 12’ to 18’), 2 3/8" tubing run cartridges (lengths typically 24’ to 36’) and the 2 3/8" tubing run disposable fiberglass filters (lengths typically 30’ with several installations of 60’).

DOWN HOLE FILTERS: Run Life

The average run life of 164 tubing filter installations (all types) is 126 days which is a 135% increase over the run life average prior to the filter installation in a well. Pump filters account for 77 installations and have an average run time of 87 days and an average improve of 71%. A plot of the run life distribution for filtered (all types) and unfiltered installations show that the curve is shifted to t he right in favor of the filtered runs( Fig. 1). The 42 tubing filters currently in the hole have an average run life of 185 day and an average 179% improvement. The nine pump filters currently in the hole have an average run life of 127 days and an average 95% improvement.

ECONOMICS:

The 538 unfiltered pulls recorded in the database cost $1.883MM. The daily pull cost for these runs were $54.63 with a total run time of 34,466 days. The total cost for the 239 runs with filters was $1.021MM. This cost includes the initial cost of the filters and cartridges for subsequent pulls for the cartridge type of filters. Total filter costs were $0.185MM. at 22,495 days of total run time, the daily cost was $45.40 The pull cost savings amounts to $9.24 per day/well (Table 1). The average cost of the filters per pull was $773.00 Cleaning and re-running the fiberglass filters have helped in keeping the costs of the filters down.

CANDIDATE SELECTION:

Selection of what type of method to use on a particular well is based upon the average sand load that the well experiences and its liquid production rate.

1. Wells producing more than ten pounds of sand per day should have a down hole filter.

2. A transition zone between five and ten pounds of sand per day for the down hole filters is used and the method used is subject to the average run time of the prior pulls. If the run times are short, a filter is recommended.

3. Pump filters are recommended where liquid and sand production is low. Cost is a prime concern for these types of wells.

4. Tubing filters are recommended for moderate wells in the ten to thirty pounds of sand per day range.

5. Minimum length of cartridge type tubing filters should be 18 feet. The length of the cartridge type filter should increase with increased production and sand loading.

6. For wells producing a high volume of liquids and sand should have multiple lengths of fiberglass tubing filters installed.

Stanley Filter Company
10061 E. 52nd Street
Tulsa, OK 74146