Lease Pumper's Handbook Published by the Commission on Marginally Producing Oil and Gas Wells of Oklahoma, First Edition 2003 Written by Leslie V. Langston Table of Contents Introductions A. Cover Sheet Book Title B. Publishing Information First Edition, 2003
 




The Lease Pumper's Handbook

Published by the Commission on Marginally Producing Oil and Gas Wells of Oklahoma, First Edition 2003 Written by Leslie V. Langston Table of Contents Introductions A. Cover Sheet Book Title B. Publishing Information First Edition, 2003

 

Written by Leslie V. Langston

 

Publishing Information. First Edition, 2003. C. Foreword. Rick Chapman, Executive Director (1996-2000) Commission on Marginally Producing Oil and Gas Wells, State of Oklahoma. D. Dedication. John A. Taylor, Chairman (1992-1998) Commission on Marginally Producing Oil And Gas Wells, State of Oklahoma. E. Author’s Introduction. Leslie V. Langston, Author, First Edition F. Commission Introduction. Liz Fajen, Executive Director, Commission on Marginally Producing Oil and Gas Wells, State of Oklahoma.

 

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  The Lease Pumper’s Handbook

 Chapter 12

 Gauging and Analyzing Daily Production

 Section D

 UNITIZING THE RESERVOIR AND COMMINGLING PRODUCTION.

 D-1. Satellite Tank Batteries. 

A satellite tank battery is a sub-tank battery located between part of the wells and the main tank battery. Gas may be sold from a satellite tank battery and water may be removed and pumped into the water disposal system, but the oil is retained and piped to the main tank battery where it is combined with other oil produced from the lease. Satellite tank batteries are used on leases where wells are scattered over a large area to simplify operations and reduce line lengths. Figure 1 illustrates a large satellite tank battery with the header located at the far right. Next is a line heater that prevents the regular separator from developing ice in the line during winter months. There are two vertical separators, one heater/treater for testing the wells, and a communication building that contains equipment to send a message to both the lease pumper and an answering service when problems occur. It also has the ability to shut in all the wells. In addition, it can be set up to automatically test the wells in a rotating manner. Figure 1. A large satellite tank battery with no stock tanks. 

D-2. Problems and Solutions for Combined Flow Lines

operations that flow the produced emulsion from two or more wells through one common flow line to the tank battery is the simplest form of a satellite arrangement. This saves the oil company the cost of purchasing and installing new long flow lines as well as future maintenance of the second or third line. While the cost of a flow line can be saved, this arrangement presents new problems to the lease pumper. For example, how can a monthly production test on each well be obtained without shutting in each well for one day each month during testing? Even more important when producing marginal wells is the problem of testing combined emulsions. Until all oil and water in the flow line junction point of the two lines to the tank battery is produced, the combined emulsion is being tested. A large part of the test emulsion is still contained in the flow line when the test is over. The individual well tester. The obvious answer to the testing problem is to move the well test to the well location site, rather than performing it at the tank battery. After selecting a convenient spot near the well or the edge of the location, a testing manifold can be installed. The junction point can be turned into a satellite tank battery. A typical tester is shown in Figure 2. The testing manifold is made by cutting the line and placing the following fittings into it in the order given: · Tee · 6-inch nipple · Plug valve · 6-inch nipple · Second tee · 6-inch nipple · Union. Figure 2. An individual well tester with a quarter-barrel dump used to test wells at the well location. The tees are installed running, and in each tee a 6-inch nipple and a plug valve are installed, completing the test manifold. Optionally the two test valves can be left standing vertically or pointing to the side with all three valve stems pointing up. This is the most common position. A trailer-mounted individual well tester can be brought to the well location. Once connected with satisfactory pressure-rated flexible hoses it is ready to test the well. The individual well tester will allow the pumper to separate the entering emulsion into gas and liquid, measure the amount of each, then allow them to recombine into the flow line to be produced to the tank battery. A sampler will periodically take a liquid sample. At the end of the test the liquid sample is blended, then two samples are removed and run through a shake-out machine or centrifuge to determine the percentages of oil and water in the produced fluid. This, along with a gas chart with appropriate information, completes the test. Well tests at the satellite tank batteries. Occasionally, it is not satisfactory to move well testing to each individual well location, making it necessary to move the testing equipment to the junction point where lines come together. At this point a bypass header should be installed that connects all wells to a test separator. One well at a time should be diverted through the test separator for testing purposes. Occasionally, however, there are other needs, such as separating the water for water disposal or gas sales to the gas company. This creates a recognizable satellite tank battery. It does not necessarily contain a flow splitter, but instead may contain heater/treaters, line heaters, water tanks, or other combinations of equipment. The rule of thumb is that the equipment is installed to meet the operator’s needs. There will seldom be two identical satellite tank batteries. Operation of satellite tank batteries. Common functions of a satellite tank battery include: · Well testing · Water separation for disposal · Gas separation for sale or re-injection · Pre-treatment of oil or water. The operation of the satellite tank battery will be defined by the operator. Since the purpose and style vary widely, it is not possible to define every situation. 

D-3. Unitizing Fields Under One Operator. 

Whole books have been written explaining the need and processes for unitizing an oilfield. This section includes only some of the high points. When a field is unitized, one operator, usually a major operator of the wells in the reservoir, will take over the operation of the reservoir and field for the life of the wells. This unitized field is a long-term operation. Every well in the field is tested with approved witnesses observing every well test. These individual daily well tests record the ability of each well to produce gas, oil, and water. All of these figures are added together, and a percentage value of the unit for each well and operator is established. The unitized field protects all well owners from formation abuse to their interests by those operators who produce their wells in a manner that benefit them only while causing damage and loss of production to others. It also allows beneficial enhanced recovery practices to begin and end as needed. Pressure maintenance can be implemented at higher elevations and there can be water flood at the lower sections. 

D-4. Commingling Different Pay Zones. 

When the operator has a small amount of production from two different pay zones, the rights to production are owned by the same individual or agency, and the two crudes are similar in gravity, it is possible to get a permit to produce them into a common tank battery or commingle the production together. This allows the oil to be sold more frequently and reduces the loss of the lighter ends into the atmosphere. It also eliminates the need to construct two separate tank batteries. The operator is still responsible, however, for accounting for how much oil, gas, and water was produced from each of the two zones. Two separators or heater/treaters may be required as well as provisions to meter all of the fluids produced from each reservoir. The tank battery is usually identical to a tank battery designed to combine the production facilities from two different operators. This is reviewed in the next two sections. 

D-5. Unitizing a Reservoir. 

Unitized field operations occur only in fields where two or more operators have producing wells in the same pay zone. When a reservoir is large it may extend several miles in length and width. All wells may produce from similar distances above or below sea level, or the field may be on an incline and be much higher at one end than the other. Problems in production that justify the need for unitization. Wells produce at different rates in the same field. If the reservoir is on an angle and is water driven, the operators on the higher level will produce at a high gas-to-oil ratio. In this situation, wells produce a large amount of gas and very little oil. Operators who have production in the center of the reservoir will produce a large amount of oil with very little gas. This lease has a low gas-to-oil ratio. The operators at the lower edge of the reservoir will produce less oil and more water. Over time, every action of an operator will affect the other operators. If the operator on the upper areas produces a high rate of gas and very little oil, this will lower the pressure on the upper end and cause the oil and water at the lower zones to begin moving toward this area and upward. The operator in the middle will begin to lose reservoir pressure, and water will begin to migrate in. The operator whose wells are in the lower zone will be affected by all of the operators with wells in the upper and middle zones. The gas pressure will fall, oil production will decline, and water will increase. The effects of unitizing. When the field or reservoir is unitized, one operator takes over the operation of all wells in that reservoir and operates them as an independent oil company. Usually the oil company with a larger investment and a higher capability for producing wells efficiently is selected as the operator. As part of the procedure for creating the unit, all wells are witness tested and their rate of production established. Several other factors are included, and each operator is guaranteed a share of the profits according to the value of the company’s share of the unit. The practice of overproducing high-volume gas wells will be adjusted, and a pressure maintenance program will begin. The water will be reinjected in the lower zone. In the long run gross production may be increased, but the life of the field may be extended dramatically. The operating company will be allowed to recover all operating costs before profits are distributed. 

D-6. Commingling Wells with Different Well Operators. 

To develop the ability to survive in a tough oil market, operators search for methods to lower company costs. One method gaining in popularity is to combine some of the field operations to operate as one company. Figures 3 and 4 reflect how a commingled tank battery might look. Figure 3. A commingled tank battery with two operators. The battery has three tanks, four heater/treaters, and three gas meter runs. Figure 4. Two of the heater/treaters can be owned by the operators and the third reserved for treating oil in the tank battery. The fourth is used for well testing. On the left side of Figure 3 are three gas meters and the stock tanks. On the right are four heater/treaters. Each company in the scenario tank battery has its own heater/treater with the produced crude oil dumping to one common tank battery. Each company has its own sign nearby identifying company ownership. At the lower left of each heater/treater, a small metering separator has been installed to measure oil production before it is dumped into the common or joint venture stock tanks. Figure 5 is a picture taken at the back of the heater/treaters, looking toward the stock tanks and three gas sales meters. Two are for the individual operators and the third is jointly owned as part of the tank battery. The circulating pump is located between the tank battery and the heater/treaters for convenience in treating the oil. It can also be set on automatic scheduling for continuous treatment. Figure 5. Each operator owns one header, and the closer line goes to the test heater/treater. The test gas meter is at right. Also at the back of the heater/treaters are two company headers to direct the flow of oil from the wells toward the heater/treaters. The header has a second manifold that permits the wells to be directed toward the test heater/treater. The gas meter to the right measures the produced gas from the test heater/treater and is then directed back into the operator’s gas system. The small metering separator (Figure 6) is set at the base of the heater/treater and operates at the identical gas pressure. By using gas-operated motor valves, the metering separator can be alternately filled with oil, then dumped to the tank battery. It is recorded each time it is dumped. These gauges are read daily at approximately the same time to record how the wells are producing. Figure 6. The small metering separator that measures the oil from the heater/treater before it is commingled in the tank battery. 

D-7. Working for More than One Operator. 

It is not unusual for a lease pumper to work for more than one operator. If the lease pumper is a contract pumper and is driving a personally owned vehicle, this should not create too great a problem, especially for one or two isolated nearby wells. However, if the lease pumper is driving a company-owned pickup, consuming company-purchased fuel, and working an eight hour day, it would not be possible to contract pump other wells unless it was fully authorized and approved by the company that is supplying the vehicle and fuel. In this situation the payment check should go to the company and a special agreement for payment to the pumper for extra work time agreed upon. There are so many possibilities of how a work agreement with the employer can be agreed upon that common sense must prevail to prevent problems from developing. If the pumper is working for a small company, a workable agreement may  be possible. The company may even welcome the pumper establishing the agreement. The larger the company is, however, the more difficult it becomes to work for two operators. The employing company has enough work for the pumper to consume the entire workday, and it may not be possible to split time. Whether or not it is a gauge and telephone only situation or requires some physical work when it is indicated is another factor. Some work situations can consume considerable work time, and one job or the other may suffer for lack of attention when needed. When considering accepting a second parttime job, the pumper should: · Secure approval from the primary employer if needed. · Not let regular work suffer because of the divided responsibilities.