Miscellaneous Subsurface Methods 529 



section. A number of copies of this proposal are reproduced. One is 

 used by the directional-drilling engineer, who has charge of carrying out 

 the plans illustrated. The service company whose engineers are doing 

 the directional drilling will keep a copy up to date in their local ofl&ce, 

 so that they may be able to work with the operator. The operator's engi- 

 neer or geologist definitely will need a copy to keep in touch with the 

 work as it proceeds. Each of these copies should be kept up to date each 

 day from the survey data. 



Cylinder drilling is a technique that resulted from the great number 

 of directional wells drilled at Huntington Beach, California. Since 1938 

 the prevalence of drilling wells within theoretical cylinders has increased 

 steadily. To a certain extent this system insures the drilling of mechani- 

 cally correct holes by limiting the tolerance of the drift and direction of 

 the course of the well. An imaginary cylinder is described about the pro- 

 posed well course as a center. The radii of these cylinders usually are 

 50 to 100 feet, but it has been necessary to make some of them much 

 smaller. On the proposal (fig. 256) a 25-foot-radius cylinder was speci- 

 fied from the surface to the 1,800-foot depth. As the deflection work started 

 at this point, the radius of the cylinder was increased to fifty feet. The 

 operator desired to bottom the well within a 25-foot-radius target; there- 

 fore, the cylinder was tapered at the bottom to this size. This proposal 

 shows a cross section of the two different-size cylinders in its upper right- 

 hand corner. The survey data taken as the well is drilled is first plotted on 

 the plan and section and then is transferred to the section of the cylinder. 

 This indicates graphically to the engineer whether it is necessary to in- 

 crease or decrease drift or to turn the well right or left. 



To illustrate some of the techniques used, a procedure is outlined 

 briefly for drilling a well similar to that illustrated in the proposal. 



The well would be drilled to the 1,800-foot depth, taking the usual 

 precautions to keep the hole straight. The drilling crew would take single- 

 shot pictures at intervals of not over 100 feet as hole was made. This in- 

 formation would then be converted into rectangular coordinates and verti- 

 cal depth for each point at which a reading was taken. This survey data 

 would be plotted on the plan and section of the proposal. When the 1,800- 

 foot-depth point had been reached, a directional-drilling crew would be 

 called to assist in starting the deviated hole. A deflecting tool would be 

 set at this point and would be faced in the correct direction to start the 

 well on its proposed course. 



After the deflecting-tool run, a single-shot survey would be made of 

 the results to determine whether they were satisfactory. The engineers 

 would attempt to increase the angle of the hole at the rate specified. 

 Usually this deflection can be accomplished by using different drilling 

 setups and varying the weight on the bit, speed of rotation of the pipe, and 

 amount of mud circulation. About 100 feet of hole would be drilled below 

 the deflected hole with a short drill collar and a roller reamer immediately 



