neutralized or treated to remove toxic materials before disposal; similarly any 

 residual oil must be skimmed off with a vacuum device before it can be discarded. 



Treatment, testing, and bringing into production. After the hole is 

 drilled to project depth, the strata will be tested by various means to deter- 

 mine potential petroleum productivity. Cores are often taken so geologists may 

 directly test the strata of interest. Other testing methods include electric, 

 inductive, radioactive, and sonic logging. All methods require special equip- 

 ment at the scene, usually mounted in specialized trucks. The different tech- 

 niques are similar in that a probe is lowered down the hole to send back infor- 

 mation at the various depths of interest. After the logging information is 

 collected and interpreted by geologists, a decision will be made whether to 

 bring the well into production. If the decision is not to produce, the well is 

 capped, and shutdown procedures begin at the site. If the decision is to produce, 

 casing will be set in the well to the producing layers. 



Since casing is larger in diameter and heavier than drill pipe, special 

 tongs and other equipment are needed to lower it into the well. When the 

 casing is lowered all the way and centered in the hole, cement is pumped down 

 *:hrough the inside of the casing, out the bottom, and up the outside of the 

 Ldsing. The cement holds the casing firmly and permanently seals the inside of 

 the hole. Cement trucks and special jet pumps are required for this job. 

 Since cementing must be accomplished rapidly, there are usually several cement 

 trucks and pumps at the site during the process. 



With the casing set, one or more sets of production tubing may be lowered 

 into the well along with "tubing packers," which are seals to help control 

 pressure. Tubing is used inside the well to protect the casing from mechanical 

 or corrosive damage during the life of the well and to allow better control of 

 fluid flow (API, 1962). The well will then be brought into production. This 

 may be as simple as drilling a little further into the strata that bear petro- 

 leum. In many cases, however, there may be numerous productive strata, and the 

 one(s) chosen for production have casing passing through them. As a result, 

 the casing will have to be perforated or opened to the strata. This again 

 requires specialized trucks that enter the site. A charge is lowered to the 

 required depth and a group of bullets, or extremely high temperature jet blasts, 

 open the casing. 



Depending on the type of strata, specialized treatment may be required. 

 Since gulf coastal strata are essentially sedimentary, fracturing may be neces- 

 sary to open up the formation. Fracturing is the pumping of sand into a forma- 

 tion to keep the cracks open. Again the process is accomplished with a series 

 of truck-mounted pumps and tanks. Another common treatment is acidizing: acid 

 is pumped under pressure into formations to open the rock. This type of treat- 

 ment is often used in limestone. 



99 



