Let's consider the main stages of development of oil and gas fields, since this issue is relevant today. Black gold is a strategic raw material for our country. That is why close attention is paid to issues related to the development of natural hydrocarbon deposits.
The concept of well development
What are the stages of oil development? The system involves the organization of the movement of oil in wells and reservoirs. The following points stand out:
- order of commissioning facilities;
- grid of well placement at facilities, order and type of their commissioning;
- options for balance adjustment and application of reservoir energy.
Distinguish between systems for the development of individual deposits and multilayer deposits of natural hydrocarbons.
Objectdevelopment
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;
- technology of using wells, applied equipment.
Classification of objects
When analyzing the stages of field development, it is necessary to note the division of objects into returnable and independent ones. The former involve the development of wells that are operated by another facility.
The grid of wells assumes the presence of injection and production types at a specific object with the obligatory indication of the distances between them (density). The shape of the grid can be triangular, square, and also polygonal.
Density means the ratio of the area of the oil-bearing indicator to the number of producing wells. This indicator assumes consideration of specific conditions. For example, since the second half of the last century at the Tuymazinskoye field, the grid density has been - (30 to 60) 104 m2/SW. Depending on the stage of field development, this indicator may vary.
Density characterizes the duration of the development period, patterns of changes in economic and technical indicators: current,total production, water-oil ratio.
Development of deposits at a late stage implies a significant accumulated (total) capacity of the well, making it cost-effective and beneficial for the enterprise.
Stages
There are four stages in the development of reservoir type deposits:
- Development of the object of operation.
- Maintaining a decent level of hydrocarbon fuel production.
- Significant decline in oil and gas production.
- Final stage.
Distinctive characteristics of the first stage
The following indicators are typical for the first stage of gas field development:
- intensive growth in production (growth reaches 2% annually);
- a sharp drop in reservoir pressure;
- low water cut;
- achieving an oil recovery factor of 10 points.
The duration of this stage is determined by the industrial value of the deposit, on average it is 4-5 years. The end of the stage is the point of a sharp change in the production rate curve.
Second stage: stable production
What is this stage of field development? It is characterized by the following parameters:
- stable high production for 3-7 years for wells with low oil viscosity, 1-2 years for high viscosity;
- growth in the number of wells tothe maximum rate (thanks to the reserve fund);
- shutdown of a number of wells due to flooding and transfer to mechanized mining option;
- current oil recovery factor is about 30-50 points.
Third stage: reduction in volumes
It implies a significant reduction in hydrocarbon production. It is characterized by the following features:
- decrease in production annually by 10-20 percent;
- exhale at the end of the stage at the rate of oil and gas extraction 1-2%;
- there is a tendency to reduce the stock of wells due to shutdown due to flooding;
- increase in liquid coefficients by the end of the stage by about 55 points for fields with higher viscosity.
This stage is considered the most complex and difficult within the whole field development technology. The main task at this stage of work is a significant slowdown in 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
Fourth - the latest stage of oil field development, which is characterized by the following features:
- insignificant, declining rates of extraction of hydrocarbon raw materials (oil, gas);
- Significant liquid withdrawal rate;
- a sharp loss of functioning and economic feasibility of wells due to flooding.
The duration of the fourth stage is comparable to the previous three, characterized bythe limit of economic feasibility and profitability. Most often, such a limit occurs when the product is 98% water-cut.
Ways to increase production speed and volumes
In order to maintain reservoir movement and increase the reservoir recovery factor, which has a significant range depending on the characteristics of the field, pumping under pressure into the reservoirs of gas or water through special injection wells is used.
Currently, intra-contour, contour, areal flooding of oil reservoirs is used. With aquifer, water is pumped into the reservoir through an injection well, which is located along the perimeter of the deposits behind the outer contour of the oil-bearing capacity. Production wells are placed inside the contour in rows that are parallel to it.
In large fields, in-contour waterflooding is used, which involves cutting injection rows into several operational blocks. Thanks to waterflooding, oil recovery of deposits increases. In addition to this method of increasing the economic attractiveness of natural hydrocarbon deposits, other methods are also used. For example, today alkaline flooding is carried out, foams and emulsions are used, polymer flooding is in operation, oil is displaced by steam and hot water.
Conclusion
The oil and gas field development technology consists of four stages:
- development;
- consistently high level of resource extraction;
- decrease in deposits;
- 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 reserves of hydrocarbons and the economic feasibility of production.
