RU2224875C2 - Method of limiting water influx into extracting wells - Google Patents

Abstract

FIELD: oil and gas extracting industry. SUBSTANCE: method includes wells examination and later supplying water-sealing compounds into layer, said compounds having selective penetrative capabilities. On basis of wells examination amount of cracks in extraction area and amount of space behind column which is free of hydrated cement are determined. Then, amount of cement mortar sufficient for filling said spaces and cracks in the layer is supplied into the well. Water-sealing compounds are supplied after mortar solidification and perforation of watered layer portions. After supplying water-sealing compounds for their reinforcement cement mortar is pumped again. Well is placed in operation after repetitive punching of productive layer portions. Mortar may also include plasticizers and water discharge lessening compounds. EFFECT: increased effectiveness of isolating water influx in extracting wells and cracked collectors. 2 cl

Description

The invention relates to the field of oil production and is intended to isolate the influx of water to production wells.

A known method of isolating the influx of water into oil wells by pumping into waterlogged strata of water-proof sediment-forming [1] or gel-forming compounds [2].

The closest of the analogues is a method of limiting water inflow into production wells, including the study of wells and the subsequent injection of water-proofing sedimentary, gel-forming compositions with selective penetration into them [3].

The technical challenge facing the invention is to increase the efficiency of isolation of the influx of water to production wells in fractured reservoirs and in the presence of cracks in the cement stone.

To solve this problem, in the process of limiting water inflow into production wells, including well research and subsequent injection into the formation of water-proof sedimentary, gel-forming compounds with selective penetrating ability, the volume of cracks in the bottom-hole formation zone (FZP) and the volume of annular space cement and previously before the injection of waterproofing compositions, cement solution is pumped into the reservoir in a volume that ensures filling for Olona voids and cracks in the formation, and water shutoff injection compositions is carried out after the solidification of cement slurry, and perforating the formation flooded areas, wherein after injection of waterproofing formulations for their fastening newly injected cement slurry and injected into the wellbore after the operation reperforatsii productive reservoir regions.

To increase mobility and penetrating properties, plasticizers and fluid loss reducers are introduced into the cement mortar with mixing water.

To implement the method according to the results of geophysical studies, the quality and presence of cement stone behind the production string and the injectivity of the well determine the volume of cracks in the bottom-hole zone of the formation and the volume of annular space free from cement stone in the interval of the opened productive formations. It has been practically established that 2-8 m ³ cement mortar is required to isolate cracks and voids.

To increase and maintain the mobility of the cement mortar during its preparation, chemical additives are introduced into the mixing water: plasticizers and fluid loss reducers.

The following reagents were tested and showed good results as plasticizers at temperatures up to 130 ° C, in wt.%: Sulfite yeast mash (SDB) - 0.1-1.0; condensed sulphite-alcohol bard (KSSB) - 0.1-0.7; ferrochromlignosulfonate (FHLS) - 0.2-0.6; forest chemical polyphenol (PFLH) - 0.1-0.3; oxyl - 0, -3.0; sodium and potassium dichromates - 0.3-1.0; sulfonol NP-1a (according to TU-6-01-1816-75) - 0.075-0.15. To reduce water loss, you can use: oxyl - 0.1-3.0; dextrin, modified starch (MK) - 0.2-1.5; hypane - 0.1-0.5; carboxymethyl cellulose (CMC) - 0.5-2.0. It is established that oksil is a universal remedy.

The cement mortar is injected into the formation through a tubing string installed in the well with a packer that protects the production string from high pressure, of the order of 30-50 MPa, which is necessary for pumping cement into the reservoir and the annulus.

After the cement slurry is pumped, the well is left under pressure for the duration of the cement slurry. Then, perforation is carried out in the interval of the flooded sections of the formation and through the obtained special holes into the formation using any known technology, with the mixing of aqueous solutions of reagents (compositions) at the wellhead or in the formation, water-insulating compositions are pumped.

For example, carry out sequential injection into the reservoir of sediment-forming (OS) and gelling compositions (GeO). A precipitate-forming composition is prepared by the method of simultaneous injection of precipitate-forming solutions of sodium silicate (6-8%) and calcium chlorides (1-2%), separately prepared in containers. The solutions are injected in separate lines and are connected before entering the well in the tee and then into the tubing as they move in the well and in the formation. The interaction of these components leads to the formation of an insoluble precipitate in the form of bulk particles of silicon oxide. A heavy silica sludge blocks the washed intervals of the formation.

As a second rim, a gel-forming composition is injected, which is obtained by simultaneous injection of aqueous solutions of sodium silicate (5-7%) and calcium chloride (0.4-0.5%). The composition of GeO differs from the composition of the OS by the concentration of components. To obtain a gel, a solution with a low content of calcium chloride is used, in contrast to the preparation of a sediment-forming composition. The use of hydrochloric acid is also envisaged as gelation. When these chemicals react, a crosslinked gel structure is formed. The gel formed in the formation attaches to the sediment that has fallen in the filtration channels of the formation, which enhances the effect of increasing the filtration resistance of the washed intervals of the formation.

The above formulations can be used to act on the formation individually - either OS or GeO.

The injection is carried out in a volume of 40-80 m ³ at a pressure of not more than 11 MPa.

After pumping water-insulating compositions to fix them into the injection zone, up to 1-2 m ^{3 of} cement mortar is pressed. As a buffer fluid between water-insulating compositions and cement mortar using industrial water.

The well is maintained for the period of gel formation (or sludge) and cement mortar hardening, after which the formation is reperforated and the well is put into operation.

Sources of information

1. RU No. 2039208, 1995.

US No. 4735265, 1988.

RU No. 2064571, 1996.

Claims (2)

1. A method of limiting the flow of water into production wells, including the study of wells and the subsequent injection into the formation of water-proof sediment, gel-forming compositions with selective penetrating ability, characterized in that according to the results of the study of the wells, the volume of cracks in the bottom-hole formation zone and the volume free from cement are determined annular space and pumped cement in a volume that ensures the filling of the indicated voids and cracks in the reservoir, and the injection of waterproofing compounds prov they are dressed after the cement mortar hardens and the perforated sections of the formation are perforated, and after injecting the indicated compositions, cement cement is again pumped to fix them and the well is put into operation after reperforation of the productive sections of the formation. 2. The method according to claim 1, characterized in that plasticizers and fluid loss reducers are introduced into the cement mortar with mixing water.