Oil casing is the lifeline to maintain the operation of oil wells

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Oil casing is the lifeline of oil well operation. Due to different geological conditions, the underground force state is complex, and the comprehensive effect of tension, compression, bending and torsion stress on the pipe body, which puts forward higher requirements for the quality of the casing itself. Once the casing itself is damaged for some reason, it may cause the entire well to be reduced in production or even scrapped. The oil casing has the following characteristics:

(1) Domestic oil casing shall be in accordance with SY/T6194-96, and the length of casing shall be indefinite, with a range of 8-13m. However, sleeves not shorter than 6m can be provided, and the number of them shall not exceed 20%.

(2) The inner and outer surfaces of the casing shall be free of folds, hairlines, separation layers, cracks, rolling folds and scars. These defects shall be completely removed to a depth not exceeding 12.5 percent of the nominal wall thickness.

(3) The outer surface of the coupling shall be free of defects such as folding, hairline, separation, crack, rolling and scarring.

(4) The thread surface of casing and coupling shall be smooth, and no burrs, tearing and other defects sufficient to interrupt the thread to affect the strength and tight connection are allowed.

Steel resources supply pressure is still large. In mid-May, the average daily output of crude steel of key iron and steel enterprises was 1.6921 million tons. It is estimated that the average daily output of crude steel in the whole country in mid-May was 2.0395 million tons, down 0.25 percent from the previous month. Although the production capacity of steel mills has begun to fall, the magnitude of this decline is almost negligible. The ultra-high production makes it difficult for Chinese steel prices to rise sharply.

Domestic market demand is not strong, steel prices lack of momentum. According to data released by the China Federation of Logistics and Purchasing, China's manufacturing purchasing managers' index (PMI) was 50.4 per cent in May 2012, down 2.9 percentage points from the previous month. The production index was 52.9 per cent, which, while continuing to be above the threshold, was 4.3 percentage points lower than the previous month and the lowest since December 2011, indicating a marked slowdown in the growth rate of production by manufacturing firms. The index of new orders was 49.8 per cent, down 4.7 percentage points from the previous month and below the critical point this month after four consecutive months of being above the critical point, indicating signs of a decline in demand in the manufacturing market.