AN OIL WELL

Wanganui Chronicle, Volume LXXXIII, Issue 19731, 28 December 1926, Page 2

AN OIL WELL

HOW IT WAS CLOSED GREAT ENGINEERING FEAT Recently one of the most famous oil wells of the world was closed—the ‘ < F7 ,; bore in Persia, -drilled hy the Anglo-Persian Oil Co. Oil was struck in it in November. 1911, kind it was only recently that the chairman of the directors of the company (Sir Carles Greenway) told shareholders that the well was in a dangerous condition and would have to be closed, as the oil it yielded could equally well be drfawn off in other quarters. At. the time oil was struck there was a few other producers in the locality, but none of them of great volume. According to’a statement issued by the company it appears that there was some anxiety kimong the held staff regarding its ability to meet the requirements of the new petroleum, refinery at Abadan, in Persia, as well as to supply oil for crude shipments. At first F 7 came in with only an initial production of ’about 30,000 gallons a day, which was nothing compared to its subsequent production. It was characteristic of the fortunate and equable character of the history of the well, however, that it should have begun so quietly. The staff then hhd had little experience of high pressures and enorm- ! ous productions such as were experienc- ; ed later, and had oil com e_ with the full force of the later output the oil might easily have done irretrievable damage. As it was, the oil-bearing limestone had barely been touched ■when the well began to flow and there was ample time to withdraw the tools and furnish the bore with all the requisite head-fittings. Personality in Wells. The behaviour of the well wtas in vivid contrast to those w'hich break loose with enormous gushes, and not I only wreck themselves, but also affect ! the prosperity of a field. The most {.famous example of this type was the Mexican well Dos Bocas, which burst suddenly into gigantic production, took fire, and burnt itself out in lan enormous blackened crater. Tn Ihe trade journal of the Anglo-Persian Company it is said that to the petroleum engineer an oil well has character and personality apart from the oil it conveys. He knmfs that there are generous wells and mean wells, equable wells the history of which is one of orderly progress and production, land furious wells. Every little incident connected with the sinking and drilling into oil, the various troubles which may occur during these operations, and all the happenings of its later career combine in the imagination of the oil engineer to give to a well almost the personality of a living thing. The record of F 7 seems to have captured the imagination of people both in Persia and in England because of the steady increase of its output and the manner in which that output wins maintained until the enormous quantity of more than 6,700,000 tons of oil had flowed from it. One of the chief achievements of F 7 was that its flow appears to have induced a British Royal Commission which visited Persia in 1913 to conduct an investigation into the potentialities of the oilfields. At that time F 7 had not developed its productiveness fully. The commission reported favourably on the outlook for Persia, and hardly had it done so when suddenly F 7 began to yield on a vast sdale. This confirmation of the favour able report of the commission influenced lhe British Government in June, 1914, to obtain a controlling interest in the company. It has often been said that the purchase of that interest was almost as important a transaction as the purchase by Disraeli of the shares in the Suez Canal Company. To some extent th e transaction relieved Great Britain of dependence upon foreign sources for its supply of fuel oil during the war. At times the holding of the Government in the Anglo-Persian Company has been challenged, but suggestions that the shares should be sold to private organisations have not been adopted by British Cabinets. The British nation, through its Government, still hfes a large interest in the fortunes of the Persian oilfields.

Record Productivity. Tn 1914 the quantity of oil required for refinery purposes and for shipment was only about 250,000 gallons a day. In .1917, with a large pipeline available and until the end of its dareer, F 7 produced 450,000 gallons a day, thereby setting up a remarkable record in the history of oil well productivity. During all these years the condition of the well head fittings was a source of constant anxiety bcclause of the danger that they would yield to the heavy and unceasing pressure of the oil which, suddenly released, might catch fire. In the end it was decided that the only thing to do was to "shut in” the well, as no stronger fittings could be substituted. In March, 1926, the work of " mudding off” the well wlas ordered. It was carried to a successful conclusion by the following morning. The operation of restraining the enormous subterranean forces for which F 7 was the outlet was carried through without a hitch. It was an engineering triumph, and lias been so recognised in scientific circles. The problem Was to force mud down a hole | more than 1,305 ft deep, up .which oil I was rushing at tremendous speed, and | with a pressure of hundreds of pounds ; to the square inch behind it. The holo | opened out at the bottom into great | fissures and cavities into which the mud j might slip away and dislappear. First i lof all plant to carry the mud and to : drop it into the hole had to be conjstructed round the well. The mud it- ' self had to be boiled, as it was more • viscous in that state than if merely mixed with cold water. Then it had to I be run into three pits of sufficient cap- ; [acity to fill the well three times over, i I allowance being thus made for the loss of considerable quantities of mud in the! fissures of the oil rork. In addition ! hundreds of clay balls about 2in. in | diameter, made of clay mixed with 1 chopped strands of Manila rope, had to be prepared to go into the hole with ! the mud. to assist in srtoppMig crevices in the hidden limestone. i On the morning of March 23 F 7 was j ciosed, ared was kept closed for 30 minutes in order to allow separation of oil !and gas to take place in the well. Then • the mud contamers were opened and I the fluid jnud was. poured into the well ! along with the day b&IIs which were ' fed in by hand. Gradually it was seen ' l that the operation was a success, but i for some days a pressure- of 2t)blbs to i th© square ine-h was iwai®tarrted to force . the- mud bae-lt into- the rock and prevent any return of oil into the well. This operation is stiff going on in an increasingly smarter measure, but there are no .signs of oil or gas or pressure, so that the well may be regarded as effectually closed..