The disclosure is directed to methods and compositions delaying the gelation of polymers in water flooding by sequentially or co-injecting a carboxylate-containing polymer solution, a gel-delaying polymer, and gelation agent into a hydrocarbon reservoir. Delays of weeks are observed.

The disclosure is directed to methods and compositions delaying the gelation of polymers in water flooding by sequentially or co-injecting a carboxylate-containing polymer solution, a gel-delaying polymer, and gelation agent into a hydrocarbon reservoir. Delays of weeks are observed.

The disclosure is directed to methods and compositions delaying the gelation of polymers in water flooding by sequentially or co-injecting a carboxylate-containing polymer solution, a gel-delaying polymer, and gelation agent into a hydrocarbon reservoir. Delays of weeks are observed.

Nano-sized mixed metal oxide carriers capable of delivering a well treatment additive for a sustained or extended period of time in the environment of use, methods of making the nanoparticles, and uses thereof are described herein. The nanoparticles can have a formula of:

A/[M.sub.x.sup.1M.sub.y.sup.2M.sub.z.sup.3]O.sub.nH.sub.m

where x is 0.03 to 3, y is 0.01 to 0.4, z is 0.01 to 0.4 and n and m are determined by the oxidation states of the other elements, and M.sup.1 can be aluminum (Al), gallium (Ga), indium (In), or thallium (Tl). M.sup.2 and M.sup.3 are not the same and can be a Column 2 metal, Column 14 metal, or a transition metal. A is can be a treatment additive.

A method for filling an oil and gas well of a fractured oil and gas reservoir with pack-off particles to reduce water and increase oil production comprises the following steps: (1) injecting a filling liquid carrying pack-off particles into a wellbore and a fracture via a wellhead, until a stratum crack/fracture extension pressure is reached or exceeded, or until an injection amount per unit injection pressure is close to zero, or until a preset filling amount of pack-off particles is reached; (2) launching production. The present invention efficiently addresses the problem of water channeling and water production existing in various fractures, by direct filling and recovery filling of the fractures, directly filling of the annular space, and filling from the water injection well to the production well. In particular, by utilizing two-pressure staged pressurizing filling and recovery filling, the pack-off particles smoothly enter unopened fractures, so that the blocking effect of the fractures is effectively improved, the flow conductivity of various fractures is reduced, and the water production of the well is reduced; meanwhile, the pressure gradient during the production of the matrix is further improved, the producibility of the matrix oil and gas is improved, and accordingly, the recovery ratio is improved.

A method for filling an oil and gas well of a fractured oil and gas reservoir with pack-off particles to reduce water and increase oil production comprises the following steps: (1) injecting a filling liquid carrying pack-off particles into a wellbore and a fracture via a wellhead, until a stratum crack/fracture extension pressure is reached or exceeded, or until an injection amount per unit injection pressure is close to zero, or until a preset filling amount of pack-off particles is reached; (2) launching production. The present invention efficiently addresses the problem of water channeling and water production existing in various fractures, by direct filling and recovery filling of the fractures, directly filling of the annular space, and filling from the water injection well to the production well. In particular, by utilizing two-pressure staged pressurizing filling and recovery filling, the pack-off particles smoothly enter unopened fractures, so that the blocking effect of the fractures is effectively improved, the flow conductivity of various fractures is reduced, and the water production of the well is reduced; meanwhile, the pressure gradient during the production of the matrix is further improved, the producibility of the matrix oil and gas is improved, and accordingly, the recovery ratio is improved.

Well treatments that use modified biopolymers for diversion, conformance, fluid loss control, and/or other well treatments, including a method of providing conformance, fluid loss control, or diversion in a subterranean formation, may include providing a treatment fluid including a base fluid and hydrogel particles which may include modified biopolymers that are crosslinked, the modified biopolymers may include a biopolymer backbone and side chains derived from synthetic monomers; and introducing the treatment fluid into a subterranean formation penetrated by a wellbore.

Well treatments that use modified biopolymers for diversion, conformance, fluid loss control, and/or other well treatments, including a method of providing conformance, fluid loss control, or diversion in a subterranean formation, may include providing a treatment fluid including a base fluid and hydrogel particles which may include modified biopolymers that are crosslinked, the modified biopolymers may include a biopolymer backbone and side chains derived from synthetic monomers; and introducing the treatment fluid into a subterranean formation penetrated by a wellbore.

A method for enhancing wellbore integrity and/or for sealing a wellbore by sealing formation or micro-annulus fractures in a wellbore. Such sealing can be at least partially accomplished by the use of timed expansion of an expandable sealant material that is placed a wellbore. The expansion of the expandable sealant material causes the cement surface or formation surface to be compressed, thereby creating a tight seal and/or eliminating annulus cracking, fracture, and/or gas channels in the wellbore. A degradable polymer can be used when restoration of the wellbore formation is desired.

De-oiled lost circulation materials and methods of using such materials to, for example, reduce fluid loss are provided. In some embodiments, such methods include introducing a first treatment fluid including a base fluid and a de-oiled plant material into a wellbore penetrating at least a portion of a subterranean formation including a loss zone; and allowing the de-oiled plant material to at least partially plug the loss zone.