December 13, 2011
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№ 10 (October 2011)

Salt Systems for Well Killing

   “To what extent does application of modern salt systems for well killing reduce the losses associated with repair and preventive maintenance on the oil or gas wells?”

By Michael Petrushin, Director General, Zirax

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   The use of high-quality synthetic anhydrous calcium chloride can significantly reduce the time required to stabilize a well in the required production mode. That is, the return of the well after preservation for repair or maintenance for the same (or more) production figures, which were prior to the preservation. In our estimate, the average time of bringing the well “on line” in Russia when using conventional products (such as halite or waste calcium chloride as chemical production waste) is three to six weeks. And throughout the time, the well yields significantly less gas or oil, than it was before repairs.

   That is, five weeks on average, or just a little over a month, the well does not produce at full capacity. Depending on the well flowrate, it is easy to calculate the direct losses that the operating company would incur at that.

How can the product from of Zirax help in this situation?

   First, we must remember that calcium chloride includes different varieties. There is synthetic, and there is the so-called “waste” – that is, the one that is based on the waste generated by chemical industries. Accordingly, such a product contains a lot of impurities that during the well killing can clog the hollow space both in the zone of perforation, and directly in the producing reservoir. As an example, the impurities contained in the “waste” calcium chloride (e.g., oxides of iron or magnesium) immediately react with the formation water during the kill and form sediments that cannot be dissolved. You can remove them only by hydrochloric acid (if they can dissolve in hydrochloric acid) or mechanically – both ways are very expensive.

   If you use a synthetic product, with almost no impurities, because it is made from synthetic chlorine and natural calcium carbonate, you can suceed in bringing the well “on line” much faster. About 90 percent of synthetic calcium chloride produced by Zirax under the PelletOil brand name is used specifically for well killing (i.e. repair). It is being used as drilling muds, additives for drilling muds, oil-well cement component, etc.

   Meanwhile, since 2011, Zirax has not been only supplying calcium chloride for some of its customers. The company offers the ready-made salt systems to its oil and gas producing customers containing granules of calcium chloride, corrosion inhibitors, and hydrophobic additives, allowing the industry to reduce the formation of emulsions, to limit water influx and produce more oil from the well – all the components have already been included in the synthetic granules of calcium chloride in the specified proportions by a special coating.

   Directly in the well, this new salt system, which got the name of WOTASOFT, with a hydrophobic additive – we call it a soft water-repellent agent – prevents the formation of water-oil emulsions, and the pores through which oil seeps, remain free from water. In this way, more oil seeps, whereby the resistance to its seepage is less, much of the water remains inside the reservoir, and the pores are not clogged.

To sum it up:

a) The well stabilizes much faster, virtually within three days, and

b) The well lets produce more oil, and pump less water.

   In other words, the use of the “soft” Zirax salt systems is the next, more modern and efficient level of wells operating. We already have some real examples of successful product use in Russia and the CIS countries – for example, in Kazakhstan.

   We have already done about two dozen well treatments – I cannot give the customers’ names. But proven facts are there, when the well only in one rather than two or three days gets stabilized, whereas without our solutions, this process would take at least ten or twelve days, and the customer benefit from one well could reach tens of thousands of U.S. dollars.
In fact, we have reduced the time needed to “stabilize” fivefold (!). At the same time, most oil wells started to produce 40 percent more oil. How long should this effect continue is hard to predict as we need to gather the statistics. But in any case, both the main (shorter time needed to “stabilize”) and side (improving oil recovery) effects are rather high. Even if a well yields more oil for one week only, the treatment costs pay off immediately and with a vengeance in any case.

   What has to be understood is that we are not talking about an enhanced oil recovery technology, but rather a way to better repair and maintain wells, and cut the cost of additional chemicals. As a result, you do not need to fight in the previous scale in case of emulsions, no need for additional inhibitors to clean the perforation zone.

   Again, as a result, the well produces a more pure product, oil “repels” water and the well gets stabilized in the required mode of production.

   Today we offer not just a pure calcium chloride, but enriched with organic and inorganic additives, which allow you to work more efficiently. At the same time, we are not catering only for Russia as we launched commercial shipments abroad, too. The first outbound supply was Kazakhstan, where the product had been tested on an industrial scale. They already kill wells with it in full swing over there, and the customers are very happy.

   To make it clear, we have a very intelligible promo; it’s a five-minute animation film, which talks about the technology in a detailed and popular manner. Surely, the experts would see the nuances of our offer without a promo, but for those who are still considering the use of this new product – or has never used the new salt systems from Zirax before and is willing to learn more – the film will be very useful.

   Please visit and see for yourself. I’m sure you’ll like it.
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