SU1668630A1 - Method for isolation of lost circulation zones and water influx - Google Patents

Abstract

The invention relates to the drilling of wells. The purpose of the invention is to increase the insulation efficiency by reducing the setting time while maintaining the mobility of the plugging mixture during the injection process. A portland cement solution and a saturated aqueous solution of aluminum sulfate are simultaneously pumped into the complication zone. Iron oxide sulfate 1–3 wt.% Is preliminarily introduced into the sulfate solution. The volume ratio of injected solutions is 1: (0.5 - 1.0). The plugging mixture quickly (3–5 min) sets in a quiescent state. However, after mixing during the injection process, the beginning of the setting increases to 20-30 minutes. 1 tab.

Description

The invention relates to the drilling of oil and gas wells, and specifically to a method for isolating absorbing and water-evolving formations.

The aim of the invention is to increase the isolation efficiency by reducing the setting time while maintaining the mobility of the plugging mixture during the injection process.

The goal is achieved as follows.

According to the proposed method, cement solution and a saturated aqueous solution of aluminum sulphate are simultaneously pumped into the zone of complications at the same time, into which 1–3% by weight of iron oxide sulphate is previously introduced.

The introduction of 1-3% by weight of iron oxide sulfate into a saturated solution of aluminum sulphate and its subsequent mixing with a cement mortar at the indicated ratios leads to a significant reduction in the setting time of the resulting plugging mixture under both static and dynamic conditions. For example, the setting time under dynamic conditions with a mixing ratio of 1: 0.5 is reduced to 1.5 times. The resulting plug-in mixture has a structure in the form of a thick paste, retains its mobility when pumping for a long time without setting, in a state of rest quickly gains structure, turning into a dense non-flowing mass.

A distinctive feature of the process is also the fact that iron oxide sulphate is introduced into an aqueous solution of aluminum sulphate and not into the mixing water of the cement slurry. The introduction of iron oxide sulphate into the mixing water leads to a rapid thickening of the cement slurry in the chunks of the cementing unit.

one (CA), which excludes the possibility of pumping shuttered cement into the well.

The addition of iron oxide sulphate to an aqueous solution of aluminum sulphate does not cause coagulation or sedimentation; the reagent dissolves well in an aqueous solution of aluminum sulfate.

The method is carried out as follows.

A hydromechanical packer (GMF) is lowered into the well on the drill pipe and installed above the absorbing (or water-causing) layer. In the measuring tanks of one CA, a saturated aqueous solution of aluminum sulfate (concentration of about 50 wt.%) Is prepared. To this solution, powdered iron sulfate is added in an amount of 1-3% by weight.

To isolate an absorbing (or water-developing) formation, cement solution is pumped into the cavity of the drill pipes with one CA. At the same time, an aqueous solution of aluminum sulfate containing iron oxide sulfate is pumped into the other CA. In this case, the mixing volumes of cement mortar and aluminum sulphate solution containing iron oxide sulphate are taken in a ratio of 1: (0.5-1.0), respectively.

As a result of laboratory studies (see table), it was found that when mixing cement mortar with an aqueous solution of aluminum sulfate, a rapid structure-forming mixture occurs. The beginning of the setting of such a mixture under static conditions with a ratio of the volumes of the components to be mixed 1: 0.5 and 1: 1 is 5-7 minutes. However, under dynamic conditions, i.e. after mixing in

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within 15 minutes, the time it takes for these mixtures to begin to set is noticeably lengthened (31-38 minutes). This means that with an increase in the depth of delivery of the mixture, the setting time

5, it is somewhat lengthened, resulting in a slight decrease in the effectiveness of the application of the resulting plugging mixture.

After the cement pipes are injected into the cavity of the cement pipes simultaneously and simultaneously with an aqueous solution of aluminum sulfate containing iron oxide sulfate, the resulting plugging mixture is forced into the absorbing (aquifer) formation.

The advantage of this method is that the improvement of the effectiveness of insulation works is achieved by reducing the time required for the plugging

Claims (1)

20 mixtures directly in the pores, channels and fractures of the absorbing (water conducting) reservoir immediately after the end of injection. This reduces the possibility of diluting the plugging mixture with formation water and spreading it along the formation. DETAILED DESCRIPTION OF THE INVENTION A method for isolating absorptions and water penetrations, which involves simultaneously pumping a cement solution and a saturated aqueous solution of aluminum sulphate into the complication zone at the same time, characterized in that, in order to increase the insulation efficiency by reducing the setting time of the plugging the mixture in the injection process, in a saturated aqueous solution of aluminum sulfate, iron oxide sulfate is preliminarily introduced in an amount of 1-3 wt.%.