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Deep-well Drilling Technique - Ventura Avenue Field, California
By H. H. Dievendorf and F. W. Hertel, Union Oil Company, Ventura, CA.
AIME Meeting, February 1928
"This paper is intended t.o set forth the methods used in the drilling of deep wells with rotary tools and the handling of long heavy strings of casing in the Ventura Avenue field."
The following drilling fluid information is extracted from the above paper.
The Pumps and Mud Circulation
"The pump house is on the side of the rig that has the standpipes. The floor of the pump house is almost :3 ft. lower than the floor of the derrick, thus insuring a minimum lift of the mud fluid from the slush pit. The pump house is equipppd with two large mud pumps (14 by 7P-:1 by 14 in.) with 8-in. suctions and 3-in. discharge lines. These pumps are connected so that each pump can work independently or may be "compounded." By "compounding" these pumps and reducing the size of the pump liners, a pressure of over 2000 lb. can be built up.
Long settling ditches are built to drop the sand out of the mud. The slush pit is divided into two spctions. The ditch dumps into one side and the mud flows over the top of the partition into the adjoining side and is picked up by the slush pumps. This keeps a large amount of sand from rnnaining in the mud that is being circulated."
"The mud-mixing plant has a large paddle mixer that takfes the dry clay, which is hauled from a pit approximately a mile distant, and mixes it into mud fluid weighing 76 to 82 lb. per cu.ft. (10.1 to 10.9 lb/gal) Steam pumps pick up the mud from large sump holes or large tanks, and pump it to the wells, each well being connected t.o the mud-mixing plant. Each rig has a return pipeline to the mud-mixing plant, so gas-cut mud can be reconditioned. When the wells are driliing into the high-pressure oil and gas sands, a tank of surplus mud is kept at each rig."
The mud-discharge line is connected to the conductor pipe by a flange union, and is equipped with a high-pressure valve which allows the mud discharge to be run through the mud-settling ditch, or through an outside flow assembly. In case the well attempts to blowout, the combination of a blowout preventer around the drill pipe, together with the outside flow assembly, restricts the mud from being discharged from the hole faster than new mud can be pumped down to kill the gas.
17 1/4 or 19 inch hole
" Immediately following the cementing of the water string, the slush pumps are connected with the opening between the casings and heavy mud is forced down behind the water string and into the formation. If sufficient mud can be forced down in this manner, serious trouble may be eliminated. The water sands will be mudded off and will not allow the hydrostatic pressure to be exerted against the casing. The gas sands will he mudded off and prevent a possibie blowout between casings; also, the gas will not be allowed to "bubble up" through the cement and prevent the cement from setting."
Deeper and Smaller Holes
"The rotary is continul'd until the gas pressure becomes so great that further drilling is practically impossible. During the drilling of this hole, it is often npcpssary to use some heavy mineral (such as hematite or barite) to give added weight to the mud fluid to hold down the gas. By the addition of heavy minerals and without increasing the viscosity, the mud fluid can be increased in weight to as much as 105 lb. per cu. ft." (14 lb/gal)
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