Consider the main stages of development of oil and gas fields, as this issue is relevant today. Black gold is a strategic raw material for our country. That is why the issues related to the development of natural hydrocarbon deposits receive close attention.
The concept of well development
What are the stages of oil field development? The system involves the organization of oil movement in wells and reservoirs. The following points are distinguished:
- order of commissioning of facilities;
- the grid for the placement of wells at the facilities, the order and type of their commissioning;
- options for adjusting the balance and the use of reservoir energy.
Distinguish between the development of individual deposits and multilayer deposits of natural hydrocarbons.
Development Object
This is one or several layers that are allocated for technical and geological reasons for drilling and subsequent operation of one well system. For each stage of field development, it is important to consider the following parameters:
- physical and geological properties of reservoir rocks;
- physical and chemical qualities of gas, water, oil;
- natural hydrocarbon phase and oil reservoir regime;
- well utilization technology, applied equipment.
Object classification
Analyzing the stages of field development, it is necessary to note the division of objects into returnable and independent ones. The first involves the development of wells that are operated by another facility.
The grid of wells involves finding injection and producing species at a specific facility with the obligatory indication of the distance between them (density). The shape of the grid can be triangular, square, as well as polygonal.
Density refers to the ratio of the area of the oil indicator to the number of producing wells. This indicator involves the consideration of specific conditions. For example, from the second half of the last century, the grid density at the Tuymazinskoye field is - (30 to 60) · 104 m2 / SLE. Depending on the stage of field development, this indicator may vary.
Density characterizes the length of the development period, patterns of changes in economic, technical indicators: current, total production, oil and water factor.
Field development at a late stage involves a significant accumulated (total) well capacity, making it cost-effective and profitable for the enterprise.
Stages
There are four stages of development of reservoir type deposits:
- Mastering the object of exploitation.
- Maintaining a decent level of hydrocarbon fuel production.
- Significant reduction in oil and gas production.
- The final stage.
Distinctive characteristics of the first stage
The following indicators are characteristic for the first stage of gas field development:
- intensive production growth (growth reaches 2% annually);
- a sharp decrease in pressure in the reservoirs;
- low water cut of products;
- oil recovery factor of 10 points.
The duration of this stage is determined by the industrial value of the field, on average it is 4-5 years. The stage ends with a point of sharp change in the production rate curve.
Stage Two: Stable Mining
What is this stage of field development? The following parameters are characteristic of it:
- stable high level of production for 3-7 years for wells with low oil viscosity, 1-2 years with a high viscosity index;
- growth in the number of wells to a maximum (thanks to the reserve fund);
- shutdown of a certain number of wells due to flooding and transfer to a mechanized version of mining;
- the current oil recovery coefficient is about 30-50 points.
Third stage: volume reduction
It suggests a significant decrease in hydrocarbon production. The following features are characteristic of it:
- decrease in production annually by 10-20 percent;
- expiration at the end of the stage at a rate of oil and gas extraction of 1-2%;
- there is a tendency to decrease well stock due to shutdown due to flooding;
- increase in fluid coefficients by the end of the stage by about 55 points for deposits with high viscosity.
This stage is considered the most difficult and difficult in the entire technology of field development. The main task at this stage of the work is to significantly slow down the rate of production of natural hydrocarbons. The duration of this stage depends on the previous two, on average it is 10-15 years.
Final stage
The fourth is the latest stage in the development of oil fields, which is characterized by the following features:
- insignificant, decreasing rates of selection of hydrocarbons (oil, gas);
- significant rate of fluid withdrawal;
- a sharp loss in the functioning and economic feasibility of wells due to flooding.
The duration of the fourth stage is comparable with the previous three, characterized by the limit of economic feasibility and profitability. Most often, such a limit arises with a water cut of 98%.
Ways to increase the speed and volume of production
In order to maintain reservoir movement and increase the coefficient of reservoir recovery, which, depending on the characteristics of the field, has a substantial range, pumping under pressure gas or water through special injection wells is used.
Currently, in-circuit, out-of-circuit, areal flooding of oil strata is applied. During the outflow, water is pumped into the reservoir by means of an injection well, which is located along the perimeter of the deposits beyond the external oil contour. Production wells are placed inside the circuit in rows that are parallel to it.
In large fields, in-circuit flooding is used, which involves cutting into several operational blocks of the discharge rows. Thanks to water flooding, oil recovery is enhanced. In addition to this method of increasing the economic attractiveness of natural hydrocarbon deposits, other methods are also used. For example, nowadays alkaline flooding is carried out, foams and emulsions are used, polymer flooding is functioning, oil is replaced by steam and hot water.
Conclusion
The technology for developing oil and gas fields consists of four stages:
- reservoir development;
- consistently high level of resource extraction;
- decrease in the volume of deposits;
- the final stage.
Each of them is characterized by certain indicators of the quality of raw materials and production volumes. The duration of the stages is determined by the estimated hydrocarbon reserves and the economic feasibility of production.