What Is Oil Well Control?

Oil well productivity refers to the production capacity or oil production capacity of an oil well. It is used to characterize the injection and production status and development effect of the oilfield.

The Chinese meaning of production capacity is clear: refers to production capacity or oil production capacity. In oil field development, production capacity is mainly used in two aspects: single well production capacity and block, reservoir or oil field production capacity. Single well productivity refers to the oil output of an oil well when it is working at full rate (full-time well production for 24 hours), and its unit is t / d or m. / d. Block, reservoir or oil field capacity refers to the annual oil production capacity of the block, reservoir or oil field, and its unit is 10 ⁴ t / a.

The purpose of high-yield development in oilfields with few wells is to enable the oilfield to obtain the maximum recovery benefits with the minimum investment, while achieving high recovery rates. Fewer wells means less investment, and higher production means full use of development well resources to increase the utilization rate of oil and water wells to make them more effective. At the same time, high production also means increasing the speed of oilfield extraction, enabling investment to see benefits as soon as possible, accelerating investment recovery, and improving capital utilization. Generally speaking, the average daily oil production of a single well or the annual oil recovery rate of an oil field can measure whether an oil field is "highly productive", but cannot indicate whether there are "less wells"; and the density of the well pattern can indicate whether there are "less wells" and indeed cannot be explained " high yield". "Productivity efficiency" can be used to measure whether an oil field is "less well and high production".

Productivity efficiency = actual annual oil production (10 ⁴ t) in the oil field / total wells developed (ports).

In the calculation of "productivity efficiency", the total number of development wells (that is, all production wells, water injection wells, gas injection wells, observation wells, etc.) that have been drilled is used to consider "economic" factors. Because some oil fields have sufficient natural energy, there are no injection wells, while some oil fields have many injection wells due to insufficient natural energy, and the development costs of the two are very different. If only the number of production wells or the number of production wells is used to calculate the productivity efficiency, the difference in investment in development costs will be masked.

Large production efficiency means high single-well production, indicating high production. If each well in the developed oil field has high production, it indicates that the total production is high and the extraction efficiency is good, that is, the goal of fewer wells and high production is achieved. Productivity efficiency is an instantaneous value. To ensure the maximum benefits of oilfield development, a relatively high productivity efficiency value must be guaranteed each year within the life of the oilfield development.

Productivity efficiency is also a comprehensive technical indicator that reflects the development level and status of the oil field, because the actual annual oil production of the oil field indicates the level of oil recovery rate of the oil field, and the high production of the well indicates that there is a guarantee of supporting advanced technological measures, and the degree of control of reserves is high. Reservoir geology is also deepened. ^[1]

The production capacity of an oil well at a certain stage (such as month, quarter, year, etc.) can be calculated according to the following formula:

Where

q _o oil well production capacity, t / d;

Q _o the actual oil production in this oil well stage, t;

mthe actual production days corresponding to Qo, d.

It should be noted that the production capacity of an oil well or an oil field is a near-ideal production, which may be reached or maintained in the short term; however, over a long period of time (for example, months, half a year, and one year), it is often due to various Foreseeable and unforeseen reasons lead to production suspension (such as power outages, severe weather, accidents, etc.), affecting the production rate, making it difficult to achieve or maintain production capacity.

It is known from the analysis of the oilfield development process that increasing single well productivity can be achieved in the following ways (see Figure 8). In the strategy of increasing the productivity of a single well, we should first increase the drainage area of the reservoir. This is the most direct and effective method and the most economical method. The extensive application of complex well technology by foreign oilfield companies also illustrates this. The last few in Figure 8 should be complementary to the preferred method, which is a remedy after the well pattern is determined. No matter what measures are not good to open the oil layer directly.

1. Full Geological Understanding

Newly developed reservoirs must be described as finely as possible, and the types of reservoirs, reservoir morphology, fault distribution, and reservoir distribution must be identified, which plays an important role in formulating a reasonable development strategy. Through geological understanding, the distribution law of reserves is recognized, the reserves in the oil area are classified and evaluated, and the grades are classified. The high-quality reserves with high abundance of reserves are first put into development. Different mining strategies are used for different levels of reserves, including differences in development methods, well layout methods, well types, etc., so as to achieve high production with fewer wells.

The understanding of reservoir heterogeneity and sedimentary microcosm play an important role in oilfield development. They are the key analysis objects in reservoir description. An in-depth understanding of them can guide the development of oilfields. The reserves and permeability of different microfacies will be different. It is very different, so that the well deployment strategy and development strategy for different microfacies reservoirs should be different.

2. Well pattern control strategy

Drill into the oil sands body to the maximum extent, and make the oil sands body have a good injection-production correspondence relationship;

Using complex well technology to maximize single well control reserves and oil drainage area;

Determine the reasonable well spacing according to the heterogeneity of the reservoir. The well pattern is mainly divided into blocks based on the permeability level and the sedimentary microfacies divided blocks. In areas with high permeability and poor heterogeneity, wells with good physical properties in the reservoir area may be larger for the main channel area.

Use of imbalanced well distribution method.

3. Production optimization strategy

Based on a full understanding of the reservoir, how to formulate a reasonable production strategy so that the oilfield can not only well control reserves, save drilling investment, but also is suitable for oilfield development and production. This is an issue that should be considered for overall optimization and development. According to the development experience of different types of oil fields at home and abroad

It is concluded that well strategies suitable for different types of reservoirs and appropriate production stimulation measures are effective ways to improve productivity efficiency.

4. Complex Well Strategy

In order to improve crude oil recovery (IOR), recoverable reserves are increased in terms of development strategies, well patterns, and increased drainage area. Drilling technology has evolved from drilling horizontal wells to drilling complex wells (multi-branched wells). It is planned to further reduce drilling costs, increase drainage area and increase production speed, as well as the development of different special types of reservoirs, such as multi-layer reservoirs, small fault Block oil reservoir, small sand body reservoir, etc. Multi-branched wells, that is, multiple horizontal or directional wells with different branches are drilled under a main wellbore, in order to achieve the purpose of increasing the drainage area, increasing the control reserves, increasing the output, and reducing the cost. Thus greatly improving crude oil recovery.

5. Supporting measures to increase single well productivity

In addition to the overall work of the reservoir, the methods for increasing the productivity of a single well mainly include measures for the single well, which mainly include increasing fluid injection, increasing production pressure differential, single well adjustment drive, and reservoir reconstruction technology.