2). Grammar: subordinate clause

A Clause is a the group of words but it is only a part of a sentence. It has a subject and a predicate,but still it does not make complete sense without the principal part of the sentence, called principal clause.

Examples : 1. I don’t know where he lives. 2. We should remember God wherever we go. 3. He told me that he had finished his work. 4. Will you please tell me where you found this book? In the above sentences, the group of words given in bold and underlined are Clauses. Types of Clauses : there are three kinds of Clauses.

1. Principal Clause (or) Main Clause (or) Independent Clause

2. Coordinate Clause

3. Subordinate Clause (or) Dependent Clause

Principal Clause : This Clause is the main part of sentence. As it contains the subject as well as the finite verb and theobject, it can make complete sense itself. It does not have to depend upon any other Clause.

Examples : 1. She wrote a letter. 2. She is the best girl in the class. Coordinate Clause : This Clause forms part of a sentence, but in rank, it is equal to the Principal Clause. However, alone it cannot form a sentence. It is connected to a principal clause by a Coordinating conjunction, through like the Principal Clause, in itself it forms a complete sense. Examples :

1. He gets up early in the morning and goes out for a walk. 2. He is poor but he is honest. 3. You must work hard or you can’t succeed. In the above sentences, the group of words given in bold are Coordinate clauses. Here the conjunction AND, BUT, OR are called Coordinating conjunctions.

Subordinate Clause : A Subordinate Clause depends on a Main Clause for its complete meaning. Examples : 1. Though I am poor, I am happy. 2. As she was ill, she could not go to school.

3. Unless you work hard, you will fail.

WEEK 13

1. Text “Oil storage system”

2. Grammar: Compound and complex sentences

1). Read, translate and discuss the text Text “Oil storage system”

After gas has been separated from the oil and the oil has been treated to remove water and sediment (if present), the oil goes to stock tanks which are commonly referred to as the tank battery. The tanks in a tank farm will vary in number and size, depending upon the daily production of the lease and the frequency of pipeline runs. The introduction of automatic custody transfer units and their acceptance by pipelines and producers has reduced storage requirements. The total storage capacity of a tank farm is usually 3 to 7 days’ production; that is, 3 to 7 times the maximum daily production or allowable of the wells connected to the tank farm. There are usually two or more tanks in a battery, so that while oil is being shipped from one tank the other tank can be filling.

Most tanks are made of either bolted steel or welded steel. Stock tanks usually have a bottom drain outlet for draining off basic sediments and water. In some areas tanks must be cleaned frequently due to collection of paraffin and basic sediments, which can be removed through the drain outlet. Therefore tanks are equipped with cleanout plates. Cleanout plates can be removed so that a workman can enter the tank.

The point where the pipeline company connects to lease stock tanks is usually one half meter above the bottom of the tank. The space below the pipeline outlets provides room for collection of basic sediments and water. The pipeline outlet valve is sealed and closed with a metal seal when the tank is being filled and similarly locked in the open position when the tank is being emptied. Oil enters the tank at the top at the inlet opening. Usually a valve is on the inlet line so that it may be closed to prevent oil from entering the tank after the tank is full and ready for delivery. Where oil storage is controlled manually the tank is fitted with a thief or gage hatch in the tank roof so the amount of oil in the tank can be determined with a steel measuring line. The thief hatch is large enough so that a device which is called a “thief” can be lowered into the tank and samples of oil obtained to determine the basic sediments and water content in the oil and its API gravity. This operation is called “thieving” a tank. The temperature of the oil in the tank is determined while thieving the tank.

When storage is done automatically, devices called liquid level controllers signal when tanks are filled and valves open and close according to a prearranged schedule. Salt water often is extracted with the oil as trolly oil and the storage of such water is an important part of extraction works. Such water after its processing can be used for pressure recovery or watering of oil reservoirs in order to increase total production rate. Sometimes water is pumped back to the reservoir for increasing of oil and gas ultimate production. System of formation water storage and processing includes separators, reservoir, cleanout device and pumping device.

Answer the following questions:

How paraffin and basic sediments can be removed?

What is called “thieving” a tank?

Why the level controllers are used?

What storage capacity has a standard tank farm?

How temperature of oil in a tank can be determined?

For what purpose The API gravity is needed?

Why is it necessary to process and store the formation water?