The stratification flow allocation software of water injection well is an important guarantee for enough water injection and good water injection. Because the flow allocation of water injection well involves the coupling of wellbore tubular flow, nozzle throttling and formation seepage, at the same time, the formation parameters of each water injection formation are different, and the amount of geological requirement is also different, so the different sizes of water nozzles must be used to adjust. The high efficiency measuring/adjusting instrument of water injection well is developed according to the above principles.

In the calculation of vertical pipe flow in water injection well, the relationship between pressure and flow rate before each nozzle is established by using energy conservation equation in wellbore. Combined with nozzle loss curve and formation transient water absorption indication curve, the coupling equations at different positions in wellbore can be obtained, and the nozzle size of each formation can be calculated by iterative solution.

In the aspect of water pipe throttling calculation: By fully considering the different water nozzle structures, the N - S equation which is benefits to water nozzle flow is utilized to develop numerical simulation solution. Finally, the relationship between the pressure difference between the front and back nozzle of different sizes and the water injection amount (that is, the nozzle loss curve) is summarized.

In the aspect of formation seepage: According to different geological conditions, the seepage equations of homogeneous, duo-porosity/permeability and composite reservoirs are established, and different boundary conditions (such as faults, channel reservoirs, U-shaped reservoirs) are considered.

Chengong stratification flow allocation software of injection well: from injection wellhead to formation, the flow process of water injection well mainly includes three basic flow processes: Pipeline flow in water injection well, nozzle flow through water distributor and formation seepage. This software uses vertical pipe flow, nozzle throttling and formation seepage coupling equation to realize the following functions:

The calculation of the limit injection amount of each layer: According to the formation permeability, water quality, perforation section, formation fracture pressure and so on, calculate the optimal injection amount, wellhead pressure and so on with time variation curve;

Water injection calculation of each layer: Under the condition of given wellhead pressure and nozzle specification of each layer, the actual water injection quantity of each layer is predicted, which provides a quantitative basis for the design and allocation of team construction in geological departments;

Intelligent selection of nozzle: According to the given wellhead pressure and the design of water injection quantity in each layer, the appropriate nozzle is selected automatically, which greatly reduces the allocation time and working intensity. It can also reduce wellhead pressure, energy consumption and pipe damage as much as possible under the premise of meeting the requirement of the error of injection allocation scheme.

Calculation of water injection attenuation law: in water injection, with the increase of formation pressure, the injection volume decreases continuously, and the geological department can select the appropriate allocation period according to the attenuation law to ensure the effect of water injection.

Water injection well flow adjuster: in order to facilitate field use, micro printer and other equipment are integrated on the basis of flow allocation software to form flow adjuster. In the past, because there was no theory and method of stratified water injection, the workers changed the nozzle by experience, the test is complex so the efficiency was very low. It took 4 to 6 days to deploy a well, and replaced the nozzle of one layer would also change the injection amount of other layers, so it was difficult to adjust all layers when the number of layers was large. The instrument is used in Daqing Oilfield, so that the deployment time is reduced to an average of 2.5 days per well.