After a brief introductory discussion on the general subject of earth movements in their relationship to the drilling and produciion of oil wells, this paper takes up in greater detail a consideration of thc specific problem of slight, relatively dcep slippages resulting from low-intensity tremors in an arca subject to recurrent tremors. The area discussed is the Long Beach Harbor area of Southern California and the paper describes and analyzes the devclopmeiit and application of a preventive tcchnique involving a, bell-hole" scraping prograin that is now being followed in that area for the protection of wells during drilling and production.
In conclusion, the paper presents tangible evidence of the success of thc recoinmended preventive method.
Après une brève introduction traitant d'une façon générale des mouvements de terrain dans leurs rapports avec le forage et la production des puits de pétrole, cet exposé considère plus en détail le problème spécifique des glissemeirts légers et relativement profonds causés par des frémissements de faible intensité dans une région sujette à des frémissements périodiques. La région dont il s'agit est celle de Long Reach Harbor en Californie Méridionale et l'exposé décrit et analyse l'élaboration et l'application d'une technique préventive, comprenant une suite d'opérations de grattage en forme de cloche (, Bell-hole") qu'on pratique actuellement dans cette région dans le but de protéger les parois au cours du forage et de la production.
Dans sa conclusion, l'exposé met en avant la preuve tangible du succès de la méthode préventive recommandée. * ßaker Oil Tools Inc., Los Angeles 54, California, U.S.A.
Formation slippage has long complicated the process of coinmercial oil production in certain areas.
Deformation or actual shearing of casing caused by powerful formation thrusts has frequently brought about partial or even total loss of petroleum production, not only in isolated wells, but even in entire fields. The extent of the complication naturally varies according to the geological structure and the nature of the earth movement in the area involved. For the purpose of this paper, however, formation slippages can be divided roughly into three types, as follows: r-Slippages of a cataclysmic nature resulting from tremendous earth tremors whose epi-centers are wnerally relatively close to the area affected?. a-Slippages of a gradual, more or less continuing nature. 3-Slippages of a relatively mild nature resulting from low-intensity earth tremors.
Although this paper proposes to deal solely with formation slippages of the third type listed above, let us, for the sake of preliminary orientation, consider the three types individually.
Cataclysmic slippages Obviously there is no satisfa
