. Bulletin. resses. In wells where a string of blankpipe is landed on bottom, then one sand at a time may be per-forated and tested. A packer on the tubing may be set below theupper oil and gas sands of a producing well to fill the annular spacebetween the tubing and casing or wall of the hole while testing outthe lower sands. In doing this care must be taken to prevent the 168 UNDERGROUND CONDITIONS IN OIL FIELDS. packer sticking when it is to be pulled. The method of perforatingpipe for a test is not always satisfactory, because in drilling themud maj^ have partly sealed off the sand. THICKN
. Bulletin. resses. In wells where a string of blankpipe is landed on bottom, then one sand at a time may be per-forated and tested. A packer on the tubing may be set below theupper oil and gas sands of a producing well to fill the annular spacebetween the tubing and casing or wall of the hole while testing outthe lower sands. In doing this care must be taken to prevent the 168 UNDERGROUND CONDITIONS IN OIL FIELDS. packer sticking when it is to be pulled. The method of perforatingpipe for a test is not always satisfactory, because in drilling themud maj^ have partly sealed off the sand. THICKNESS OF SAND AND PRODUCTIVITY. The depths to top and bottom of a productive sand should becarefully measured, thus giving its thickness. (See method for stringing in with sand line (pp. 192 and 193). A study should bemade of the relationship between thickness of the sand and ultimateproduction per acre. In studying the productivity of a sand ofvarying thickness account must be taken of the fact that different. FiGfRE 34.—Sketch showing entrance of water into a properly ilrilled well because aneighboring well entered a deeper oil sand without inserting an extra string ofcasing to protect the first sand. After Bull. 82, California State Mining Bureau,p. 15. parts of the same sand may have varying factors of productivity,X^erhaps from change in porosity or from other causes. With a large gas pressure an enormous amount of oil may comefrom a few feet of sand. Some wells drilled only 2 or 3 feetinto the oil sand have made a thousand or more barrels of oil perday. \\Tiere there are several producing zones separated b}^ a fewfeet of shale, the greater part of the oil probably comes from onlyone or two zones. Furthermore, in some fields where there is sup-posed to be one producing sand, 50 to 75 feet thick, very likely onlya small part of this sand furnishes the oil. The producing parts ofthis thick sand are probably separated by fine-grained tight streaksor layers firmly cemented wit
Size: 2054px × 1216px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
