Acid stimulation methods
AssigneeSchlumberger Technology Corporation
InventorsMurtaza Ziauddin, Mahmoud Ali
Life of this patent
Estimating the term…
Abstract
Stimulation treatments are designed and performed in a manner that takes into account radial acid flow into the formation. A reservoir core plug is selected and a liner core flow test is performed. The core flow test comprises measuring a flowing fraction, injecting into the core plug a treatment volume of at least one candidate stimulation fluid at an injection rate at reservoir conditions, and measuring an effective reaction rate constant. The linear flow data are then scaled to radial flow. A skin, an acid concentration at a wormhole tip and a fluid velocity at a wormhole tip are calculated. A stimulation treatment is then performed. The method can also be performed on analog cores. The stimulation treatment may be matrix acidizing, fracture acidizing or acidizing natural fractures.
Claims19
A method for stimulating a carbonate formation, comprising:
- selecting a reservoir core plug and performing a linear core flow test, wherein the linear core flow test comprises measuring a flowing fraction, injecting into the reservoir core plug a treatment fluid volume of at least one candidate stimulation fluid at an injection rate under reservoir conditions, and measuring an effective reaction rate constant;
- scaling the measured flowing fraction and effective reaction rate constant from linear flow to radial flow to produce scaled radial-flow data;
- using the scaled radial-flow data, calculating a skin, an acid concentration at a wormhole tip, and a fluid velocity at the wormhole tip according to the treatment fluid volume and the injection rate to provide an acid stimulation model, wherein the acid stimulation model comprises a radial pore volume to breakthrough (PVBT) curve that accounts for the radial flow due to targeted wormhole lengths;
- and
- performing a stimulation treatment with a stimulation fluid based on the acid stimulation model.
A method for stimulating a carbonate formation, comprising:
- selecting an analog core plug and performing, using a computer, a virtual linear core flow test, wherein the virtual linear core flow test comprises calculating a flowing fraction, simulating an injection into the analog core plug with a treatment fluid volume of at least one candidate stimulation fluid at an injection rate under reservoir conditions, and calculating an effective reaction rate constant;
- scaling the calculated flowing fraction and effective reaction rate constant from linear flow to radial flow to produce scaled radial-flow data;
- using the scaled radial-flow data, calculating a skin, an acid concentration at a wormhole tip, and a fluid velocity at the wormhole tip according to the treatment fluid volume and the injection rate to provide a radial pore volume to breakthrough (PVBT) curve that accounts for the radial flow due to targeted wormhole lengths;
- and
- performing a stimulation treatment with a stimulation fluid based on the radial PVBT curve.
Dependencies are inferred from the claim text.