What is the development index of the oilfield?

In the process of oilfield development, a series of data that explain oilfield development according to actual production data are called development indicators. The development effect of oil field can be analyzed and evaluated by using the size and change of development index.

I. Output indicators Output indicators mainly include the following contents:

(1) daily production capacity. The total daily oil production of all oil wells in the oilfield (except planned temporary shut-in and abandoned wells) is called the daily production capacity of the oilfield, and the unit is tons/day.

(2) the daily production level. The actual daily output of the oilfield is called the daily production level, and the unit is tons/day.

The daily production capacity represents how much oil should be produced. However, due to various factors, the budgeted oil has not been actually produced. The smaller the gap between the daily production capacity and the daily production level, the better the oilfield development.

(3) Converted annual output. The converted annual output is a prediction index, that is, the output of next year is predicted according to this year's situation, and the production plan for next year is made according to the converted annual output. For old oil fields, the annual decline rate should also be considered.

④ Production scale. The production scale is the sum of the production capacity of all oil fields multiplied by the hourly rate of oil production (effective production time in a certain period).

(5) Average single well output The average single well output is obtained by dividing the actual oil field output by the actual number of production wells.

(6) Comprehensive oil-gas ratio. The comprehensive gas-oil ratio is the ratio of the actual total gas production to the actual total oil production, and the unit is m3/t, which indicates the natural energy consumption of the oilfield.

(7) Cumulative oil-gas ratio. Cumulative gas-oil ratio is the ratio of cumulative gas production to cumulative oil production, which indicates the total natural energy consumed since the oilfield was put into development.

(8) Oil production speed. Oil recovery ratio refers to the ratio of annual oil production to geological reserves, which is an index to measure the exploitation speed of oil fields. Oil recovery rate can be divided into oil field oil recovery rate, cutting zone oil recovery rate, inter-row oil recovery rate and oil well oil recovery rate, usually expressed as percentage. As long as the current daily oil production or monthly oil production is converted into annual oil production, oil production can be calculated. During normal production, shut-in time such as pressure measurement and maintenance should be cancelled.

(9) degree of recovery. The recovery degree refers to the ratio of cumulative oil production to geological reserves at a certain time in an oilfield, which reflects the recovery degree of oilfield reserves and is expressed as a percentage.

(10) The ratio of oil produced in an oilfield to geological reserves is called recovery ratio. The oil recovery rate in the waterless stage of an oil well is called waterless oil recovery rate. Anhydrous recovery is equal to the ratio of cumulative oil production to geological reserves before water breakthrough. The recovery ratio reached at the end of oilfield development is called ultimate recovery ratio. The ultimate recovery ratio is equal to the ratio of cumulative oil production to geological reserves at the end of development. The ultimate recovery factor is an index to measure the development efficiency of an oilfield, which is influenced by many factors. As long as we give full play to people's subjective initiative and adopt reasonable mining methods and advanced technologies, we can improve oil recovery.

(1 1) oil recovery index. Oil recovery index refers to the daily oil production under unit production pressure difference, and the unit is t/(d MPa). The change of oil recovery index indicates the change of oilfield driving mode.

Two. Water-related indicators Water-related indicators are as follows:

(1) water production. Water production represents the water produced by the oilfield. Daily water production refers to how much water is produced every day. Cumulative water production refers to how much water has been produced since the oilfield was put into development.

(2) Comprehensive moisture content. Comprehensive water cut refers to the percentage of water production in the total oil-water mixed output, indicating the degree of water production or flooding in the oilfield.

(3) Injection amount. The amount of water injected into the reservoir in one day is called daily injection, and the amount of water injected into the reservoir in one month is called monthly injection. The total water injection from the beginning of water injection to the present is called cumulative water injection.

④ Injection speed. Injection rate is equal to the ratio of annual injection rate to total pore volume of reservoir.

(5) degree of injection. Ratio of cumulative injection volume to total pore volume of oil layer.

(6) Injection-production ratio The injection-production ratio is called injection-production ratio. Output refers to the amount of oil, natural gas and water produced underground.

(7) Water replacement efficiency. The ratio of oil volume produced in flooded reservoir to original oil content is called water drive efficiency.

(8) Water absorption. The daily water injection rate under unit water injection pressure difference is called reservoir water absorption index. Reflect the water absorption capacity of oil layer.

Levies water injection intensity. The daily water injection quantity of the unit effective thickness oil layer of the water injection well is called water injection intensity, and the unit is m3/(d m). Whether the water injection intensity is appropriate directly affects the stability of reservoir pressure. The rising speed of water content can be adjusted by water injection intensity.

(10) water-oil ratio. Water-oil ratio refers to the ratio of water production to oil production, in m3/t, indicating how much water should be produced per ton of oil.

(1 1) water content increase rate. After water breakthrough, the percentage of water cut increase per production 1% geological reserve is called water cut increase rate. Reflect the rising speed of water cut in oil fields in different periods. It is an important index to measure the effect of oil field water injection.

(12) water injection utilization rate. The utilization ratio of water injection indicates how much injected water remains underground to drive oil, which is used to measure the effect of water injection.

Three. Pressure and differential pressure indicators The pressure and differential pressure indicators are as follows:

(1) Original formation pressure. The pressure in the middle of the oil layer measured from the exploratory well before development is called the original formation pressure, which is used to measure the driving energy of the oil field and the flow capacity of the oil well. The original formation pressure generally increases with the increase of buried depth of oil layer. After the reservoir is put into development, due to the change of formation pressure, the original formation pressure cannot be measured directly, and it can be calculated according to the depth in the middle of the reservoir.

(2) Current formation pressure. After the oilfield is put into development, the measured pressure in the middle of the reservoir in a certain period is called the current formation pressure in that period.

(3) Static pressure. After the oil well is shut in, the pressure in the middle of the reservoir measured when the pressure returns to a steady state is called static pressure, which is also called reservoir pressure. In the process of oilfield development, static pressure is a sign to measure formation energy. The change of static pressure is related to the volume of oil, gas and water injected and produced. If the production is greater than the injection, the reservoir will be in deficit and the static pressure will be lower than the original formation pressure. In order to grasp downhole performance in time, oil wells need to measure static pressure regularly.

④ Conversion pressure. Most oil fields are composed of many oil layers, some of which are deeply buried and have high pressure, while others are shallowly buried and have low pressure. Due to the different elevation in the middle of each well, the original formation pressure of the same reservoir is calculated to be high or low. It is impossible to compare wells and study the dynamic changes of oil fields only based on the measured pressure. In order to facilitate the pressure comparison between wells, the measured pressures of all wells are converted to the same altitude, and this converted pressure is called converted pressure.

(5) Flow pressure. The pressure in the middle of oil layer measured during normal production of oil well is called flowing pressure, which is referred to as flowing pressure for short. The oil flowing into the bottom of the well is lifted to the surface by the flowing pressure. The flowing pressure directly reflects the flowing capacity of the oil well.

⑥ Saturation pressure. Under the condition of high pressure in oil layer, natural gas dissolves in crude oil. In the process of crude oil flowing from the reservoir to the wellhead, the pressure decreases continuously. When the pressure drops to a certain extent, natural gas is separated from crude oil, and the corresponding pressure is called saturation pressure. For oil field development, if the saturation pressure of the oil field is low, a large choke can be used to amplify the production differential pressure, and it is not easy to degas in the formation, thus greatly improving the oil well output and the oil production speed of the oil field. Unfortunately, wells with low saturation pressure have weak flow capacity.

Once the tubing pressure. The residual pressure after oil and gas flow from the bottom hole to the wellhead is called tubing pressure, which is referred to as oil pressure for short. The oil pressure can be measured by the oil pressure gauge at the wellhead. Oil pressure depends on flowing pressure, which is related to static pressure, so underground dynamics can be analyzed according to the change of oil pressure.

Being casing pressure. The residual pressure after oil and gas are lifted from the bottom of the well to the wellhead through the annular space between tubing and casing is called casing pressure, also called compressed gas pressure, or casing pressure for short. Casing pressure also indicates the energy of the oil well when the degassing of the oil well is not serious. Oil pressure and casing pressure can directly reflect the production situation of oil wells. In the daily management of oil wells, oil pressure and casing pressure should be observed and recorded timely and accurately, and the reasons for their changes should be analyzed.

Levies back pressure. The downstream pressure can be regarded as the back pressure of the upstream flow pressure. Back pressure is caused by the flow resistance of the fluid in the pipeline. Back pressure mentioned in mine usually refers to trunk line back pressure, which is a kind of back pressure of oil production trunk line pressure to wellhead tubing pressure. Back pressure is also related to pipe diameter, pipe length, fluid viscosity, temperature and other factors.

(10) total pressure difference. The difference between the original formation pressure and the current formation pressure is called the total pressure difference. For oil fields with natural energy development, the total pressure difference represents energy consumption, so the current formation pressure is always lower than the original formation pressure. Oil fields developed by water injection are developed under the condition of maintaining formation pressure by water injection. At present, the formation pressure is usually kept near the original formation pressure. When the injection volume is greater than the production volume, the current formation pressure exceeds the original formation pressure. When the injection volume is less than the production volume, the formation is in a deficit state, which makes the current formation pressure lower than the original formation pressure.

(1 1) production pressure difference. When the oil well is closed, the reservoir pressure is in equilibrium. When the oil well begins to produce, the bottom hole pressure will suddenly drop. Because the pressure in the reservoir is still very high, a pressure difference is formed, which is called production pressure difference, also called production pressure difference or working pressure difference. Under the same geological conditions, the greater the oil production pressure difference, the higher the oil well output. However, under a certain formation pressure, when the oil production pressure difference is large to a certain extent, that is, when the flowing pressure is lower than the saturation pressure, the degassing, sand production and gas-oil ratio in the bottom hole and even in the oil layer will increase, and the oil well production will not increase or increase very little. This is unfavorable for rational oil production and maintaining long-term stable and high production of oil wells. Therefore, it is necessary to formulate a reasonable oil production pressure difference according to the oil production speed and productivity, and it cannot be enlarged at will.

(12) water injection pressure difference. The difference between the flowing pressure at the bottom of the water injection well and the current formation pressure of the water injection well is called water injection pressure difference.

(13) fluid saturation pressure difference. The difference between flow pressure and saturation pressure is called saturation pressure difference. Fluid saturation pressure difference is an important condition to measure whether oil well production is reasonable or not. When the flowing pressure is higher than the saturation pressure, the dissolved gas in crude oil will not be separated at the bottom of the well, and the production gas-oil ratio is low. If the flow pressure is lower than the saturation pressure, the dissolved gas will be separated from the oil layer, and the gas-oil ratio will be high, which will increase the viscosity and flow resistance of crude oil and affect the output. Therefore, according to the specific situation of the oilfield, it is stipulated that oil production should be carried out within a certain range of flow-saturation pressure difference.

Saturation pressure difference (14). At present, the difference between formation pressure and saturation pressure is called saturation pressure difference. Saturation pressure difference is an important criterion to measure the rationality of reservoir production. If the oilfield is produced under the condition that the formation pressure is lower than the saturation pressure, the crude oil in the reservoir will be degassed, the viscosity of the crude oil will increase, and in severe cases, the reservoir will be waxed, thus reducing the oil recovery. Therefore, it is unreasonable to produce oil under such conditions. Once this happens, measures must be taken to adjust the injection-production ratio to restore formation pressure.

(15) flow pressure gradient. Flow pressure gradient refers to the pressure per meter of liquid column during normal production of oil wells. The ratio of pressure difference and distance measured at two different points is the flow pressure gradient. It can be used to calculate the flowing pressure in the middle of oil layer. According to the change of flowing pressure gradient, it can also be judged whether the oil well produces water, and the flowing pressure gradient of the oil well with water will increase.

(16) static pressure gradient. Static pressure gradient refers to the pressure per meter of liquid column when the bottom hole pressure returns to stability after the oil well is shut in. Static pressure gradient can be used to calculate static pressure.