Based on the biaxial stress relationship, a method is derived which permits design of combined casing columns through the collapse interval without resorting to the usual cut-and-try method.
A set of illustrative nomograms is presented to solve the case for 6 'Il,-inch casing. Additional tables are included for a quicker analytical solution for other diameters. Any values for safety factors an, d mild weights, as well as buoyancy, may be considered.
R@SUM@. En prenant pour base de relation entre les eflorts biaxiaux on arrive Ci une methode permettcxnt le calcul des colonnes combinkes de acasings duns l'intervalle d'kcrasement, sans recourir U la method? habituelle des tentatives successives. Une skrie de nomogrammes illustratifs est prPsentke, pour resoudr? le cas d'une colonne de 6.6/s pouces. Pour d'autres diamt?tres, on donne des tables additionnelles permettant une solution analytique rapide. On peut prendre en considPrntion diffPrPntes valeur des coeflicients d e skcuritk, du poids de la boue et dp la poussCe de flottement.
Sullu base della relazione tra gli sforzi biussiali, si arriva ad un metodo che permette il calcolo delle colonne combinate di tubi di rivestimento nell'intervallo di schiacciamento, senza ricorrere cxl metodo solito dei tentativi successivi. Una serie di nomogrammi illustrativi vime presentata, per risolvere il cas0 di una colonna di 6.518 pollici. Tavole addizionali Sono allegate per una rapida soluzione analiticu per altri diametri. PUB essere considerato qualsiasi valore dei coemcimti di sicurezza ? d?i pesi del fango, corn? pure ddla spintn di galleggiamento.
Although these charts were computed for specific values of collapse- tension- and internal The need for solving combined casing design pressure safety factors, as well as for a specific problems on an engineering basis has long been mud weight, some hints are furnished to make recognized and discussed in the literature (1, 2). them approximately correct, for other values, Among the conditions which must be conprovided they do not differ too much. sidered in casing design, collapse is perhaps Also, it happens frequently that all grades the most important.
Due to the fact that hoop stress is and weights a function of casing indicated in the charts of longitudinal stress, that is, collapse resistance for a given total depth are not available. is affected by the degree of tension under which For these reasons, most companies compute the casing is subjected, the calculation of setting their own design charts to suit their particular depths of different sections of a casing column needs (6). becomes somewhat cumbersome, iinless a trial- Graphical (7, 8, 9) and analytical (10) methand-error method is used (3). ods are found in the literature to solve the Different charts have been publis
