SU1543048A1 - Method of cementing casing strings - Google Patents

Description

The invention relates to the construction of deep wells, and in particular to the fastening of wells under the influence of aggressive formation fluids.

The purpose of the invention is to improve the quality of fastening by preventing contact of the cement stone with the reservoir fluid through the use of the effect of contraction.

A method for cementing casing strings under aggressive conditions2 (54) A METHOD FOR CEMENTING Casing strings (57) The invention relates to the construction of deep wells and is intended for fastening wells under conditions of aggressive formation fluids. The goal is to improve the quality of fastening by preventing contact of the cement stone with the formation fluid by using the effect of contraction. Before pumping the grouting mortar into the reservoir containing aggressive fluids, the hydrophobic fluid is pumped and crushed. As a hydrophobic liquid, oil, GKZh-11, phenolic O oil is used. Using the method allows to improve the quality of fastening by preventing corrosion of cement stone. An important advantage of the method is that the phase permeability of the formation for hydrocarbon fluids remains unchanged. 1 ill., 1 tab.

formation fluid includes pumping the grout into the annulus of the well, and before pumping the grout into the reservoir containing aggressive fluids, the hydrophobic fluid is pumped and crushed.

In accordance with the proposed method, the cement slurry is in the annulus of the well from the very beginning of drilling in the absence of

1543048 A1 contact with aggressive fluid. At the same time, contracting phenomena will be compensated by the absorption of hydrophobic fluid inside the cement stone, which fills its pores and prevents the entry of aggressive fluid into them.

The drawing shows an experimental setup simulating a formation and a well.

The experimental setup contains a glass tube I, Plast modeled with artificial sandstone 2 with a permeability of 500-1000 mD. Aggressive fluid is supplied through branch 3. As an aggressive component, water saturated with hydrogen sulfide with a concentration of 3000-3500 mg / l is used. Grouting mortar 4 is poured into a cavity above artificial sandstone. The degree of interaction of the cement stone color duktov phobic GKZH-11

The method is as follows.

Oil, GKZh-11 and phenolic oil are injected into artificial sandstone in an amount that provides impregnation of the stone to a depth of 5-10 cm. A cement slurry is poured on top of the stone (Portland cement W / C = O, 5; p = 1800 kg / cm), then through the outlet is injected with liquid at a pressure equal to 0.95 hydrostatic. pressure of the column cement grout, which is kept constant throughout the experiment. After 28 days of hardening of the cement slurry, the installation is disassembled and the hardened stone is examined. The results indicate that the stone is uniform throughout its height. At a depth of 3-12 mm, oil penetration is detected. The presence of hydrogen sulfide and traces of the interaction of hydrogen sulfide with a groutstone was not detected;

At tanovka experiments were carried out according to the prototype method. To do this, artificial sandstone was clogged, as a result of which its permeability decreased, assessed by the change in the phase composition of the solidification. As the fluid use oil, and phenolic oil.

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those. the aggressive fluid is not in contact with the cemented cement of the same experimental setup at 4.2 mD. After this, grouting mortar was poured, and later the experiment was carried out according to the method described above. A study of cement stone showed that in 28 days the cement stone turned black to a depth of 15 mm. Chemical analysis showed that blackening is caused by the penetration of hydrogen sulfide dissolved in a liquid into a cement stone and the reaction between them.

The table shows the results of experiments conducted by the proposed method and the prototype method.

The practical implementation of the proposed method for mounting may be as follows. Before lowering the casing string during the last run of the bit against the reservoir containing aggressive fluid, for example, an oil bath is installed, the wellhead is closed and the wellhead is pressurized, the hydrophobic fluid is trapped in the formation. After this, the descent of the column and its cementing are carried out. The installation of a bath of hydrophobic fluid against the formation with an aggressive fluid and its crushing into the formation can be carried out after the casing is lowered.

An important advantage of the proposed method is that the creation of a hydrophobic screen on a cement stone and the presence of a hydrophobic fluid in the reservoir do not change the phase permeability for hydrocarbon fluids contained in the pores of the reservoir.

well solution, so that, with fastening

Claims (1)

A method of cementing casing strings under the influence of aggressive formation fluids by pumping cement into the annulus revealing the goal of improving quality by preventing contact. grouting stone with formation fluid due to the use of the contraction effect, before pumping grouting solution into the formation containing aggressive fluids, hydrophobic fluid is pumped. »543048 Type of hydrophobic fluid Aggressive environment The exposure time in an aggressive environment, days Depth of corrosion damage (mm) of cement stone from Prototype Aqueous solution of H ₂ 8 28 Proposed way 28 Oil 28 GKZH-11 28 Phenolic oil 28 Prototype МеС1 ₂ 60 Proposed way Oil 60 GKZH-11. 60 Phenolic oil 60 Prototype Мё5О ₄ Proposed way Oil 60 gkzh-n 60 Phenolic oil 60 HRC SHPCS IKS (lime-siliceous mixture 12 10 eleven - - - - - - four 3 four - -