No abstract

In offshore platforms, with high well density, slot recovery technique is an efficient way to target new / un-swept avenues to boost the production levels in a mature field. This leads to utilization of an appreciable length of parent bore which is an advantage to the operators globally in terms of surface facility retention and associated rig time saved. This paper discusses an actual case-study wherein dual casing exit was achieved in an offshore platform well resulting in significant time and cost savings. For the subject well the subsurface targets were quite far from the mother-bore, resulting in a plan to side-track the well at a shallow depth where double casing existed, i.e. 9-5/8″ × 13-3/8″. The options available were pilot milling and dual exit using whipstock. Unlike multi-casing exits, pilot milling is a time consuming method which requires multiple trips and involves large volume of metal swarf handling at surface. The CBL-VDL verified the presence of cement outside 9 5/8″ casing that further supported the case of dual casing exit operation. Consequently, associated risks were discussed and plans to mitigate the same were put in place. Single-trip 8-1/2″ whipstock-milling system was used to cut a window suitable for running drilling BHAs, liner, and completion equipment. The 9-5/8″ × 13-3/8″ annulus was monitored during milling and FIT test to check for any pressure communications. For well control scenario, arrangements were made for connecting the annulus to the choke manifold to ensure a closed system and thereby have provision of circulating through choke in case of gas migration in the 9-5/8″ × 13-3/8″ annulus. The window milling operation was done using sea water & intermittent Hi-vis sweeps. The window was milled successfully in a "single trip", thereby saving considerable rig time. No excess drag or held-up was observed and gauge loss on mills when pulled out of the hole was negligible. Well integrity was intact with no pressure communication in the annulus. The job was a successful one that led to finishing the well within the planned time and thereby, led to timely release of the jack up rig before the onset of adverse weather conditions. Multi-casing exit technology in two or three casing strings opens the multi-level advantages to well intervention techniques especially in situations where the wells are old with limited access due to presence of fish or other restrictions that makes the deeper section of the well non-usable. Such sections can be avoided by sidetracking at a shallow depth and also provides an opportunity to access targets that are quite far from the original mother-bore.

The success of a pilot milling operation is dependent on the mill design, adherence to correct milling parameters and precise location of stabilizing members in the bottomhole assembly (BHA), especially while milling through large casings such as 20 inch inside 30 inch conductor. This paper discusses the importance of correct mill design and stabilization of the BHA, along with field results from milling with under-gauged mill and stabilizers. Pilot milling interventions to facilitate open-hole side-tracking can be very effective and cost-efficient, especially in cases where retaining the original borehole size is necessary for further workover operations, for example, when liner is milled for this purpose. Pilot milling is a suitable option where sidetracking with a whipstock is not viable, as when casing has collapsed, with internal diameter restrictions, or situations where irreparable surface damage to conductor pipe and casing have occurred due to corrosion. Such situations might result in losing an offshore platform slot, which is a huge cost to operators. One such situation was encountered where 30 inch conductor pipe parted at the water line due to corrosion. Prolonged exposure to corrosion further led to 20 inch casing parting at the water line as well. Surface repairs were attempted but were unable to arrest annulus leakage. In order to recover the slot, an improved and specially designed pilot mill was used. A stabilized milling bottom-hole assembly with precise sizes and locations of stabilizers was incorporated. This new mill design resulted in milling 585.6 feet of 20 inch casing with an average rate of penetration (ROP) of 2.6 ft/hr. The new mill design resulted in good mill life and only two mill runs were made in the entire milling operation. Results of torque and drag simulations to study the bending stresses and torsional stresses on mill string components while milling are discussed. Catastrophic effects of using under-gauged mill and stabilizers were also examined. This improved mill and stabilized bottom-hole assembly design offers optimum ROP, improved mill life, reduced surface vibrations and a fine metal cutting structure that eases metal debris handling at surface.

No abstract

This book is a sequel to the author's well-known ' Homer' 1903 (Italian translation 1910; the author announces a second German edition) and deals with Homer himself and the secrets of his art. Pp. 5-34 give a sketch, interesting if rather depressing, of the present state of 'Homerforschung,' pp. 34-71 lay down the Gri•ndidee (in Belzner's words) that 'Der Dichter giebt uns die Regeln fiir sein Schaffen, nicht wir ihn.' Pp. 76-346 are devoted to a very minute analysis of Book 5, the longest and perhaps the least interesting of the books of the Iliad (rb 7ro~' Los ro7 vol OL" Kov (ipEL remarks the scribe of Laur. 32.3). Herr Drerup is a convinced unitarian, and his method is in essence the same as that of Blass, Rothe and Belzner, viz. to shew by means of a detailed consideration of the text that the discrepancies, weaknesses and contradictions which have caught the eye of critics from time to time all proceed from the hand of the Master, and are part of his art and his mental outlook. On the whole the results appear solid, and indeed it is a facile if tedious task to refute line by line the blind wild assertions of nineteenth century critics. At the same time the method, like any method, can be pushed to excess, and the reviewer does not feel entirely easy that every line of E came direct from Homer or was his deliberate intentional composition.The demonstration seems to import too much reasonableness into trifles, Homer never nods, and we seem on the way to a devotional Bible-exegesis.It is better to admit imperfect assimilation of material, and the limitation exercised on the artist by tradition and even vested interests. Moreover the pure psychological method is inevitably subjective, and requires keeping in control by external evidence, when there is any, and by the essential question 'what has Homer in such and such a passage done to his source ?' I cannot believe for instance that Homer invented the lists of minor personages, or that their names were chosen for their meanings and that Adpi7 is connected with ipwc (either really or in the poet's belief). I note that Herr Drerup puts Homer late, as late as the Cycle, and that the Tlepolemosepisode, the most valuable thing in the book, is called 'Dorian.' How a son of the Hercules who sacked Troy under Laomedon can be Dorian does not appear, nor why Hercules semper et ubique need connote Dorian. The remains which prove a Mycenaean settlement of Rhodes, Cos, etc. are ignored. But these are rather questions for ' Homer zweite Aufl.' T. WV. A. Tendenz, Aufbau und Quellen der Schrift vom Erhabenen. Von HERMANN MUTSCHMANN. Pp. vi + 114. Berlin : Weidmann, 1913.