Heightened the Productivity of an Eruptive Petroleum Well with Two Reservoirs by Jet Pump and Infill Well

World energy markets have been affected by the COVID-19 crisis in the years 2020-2021 [1, 2]. Investment in hydrocarbons has fallen sharply, leading to a profound imbalance between energy supply and demand [3, 4]. Although the progress of solar and wind energy over the last 10 years has been on the positive increase, they have only added to the energy supply, without replacing fossil fuels [5]. As a result of this steady increase in global demand for hydrocarbons and the decline in the number of discoveries yearly, it is necessary to increase oil production more efficiently and economically [6-10]. Oil production by oil wells is not constant over time, but their flow rates keep falling over time [11-14].

Oil production from wells is characterized by a declining flow rate over time due to various factors, including depletion of reservoir pressure, changes in reservoir characteristics, and increased viscosity of the crude oil. As oil is extracted, the natural pressure that drives the flow diminishes, leading to reduced production rates. This decline necessitates enhanced recovery techniques to maintain output levels. In specific considerations, these properties of a well are studied and optimized to increase production [15, 16]. This is the case for Well Y in field X, which has two reservoirs including the S1 reservoir and the S2 reservoir, where the S2 reservoir is below the east-facing S1 reservoir. Oil production by Well Y through reservoir S1 is natural, and over time the reservoir pressure dropped to a level where it became lower than the pressure at the bottom of the well. At the moment, with the Well Y at a standstill, there is a need for activation using the artificial lift method [17-20]. The reservoir S2 has the right petro physical characteristics (porosity, permeability, saturation, etc.), hence the need to reach it via the same well and bring it on stream. Reservoir S1 requires a well-scale optimization method, and so does reservoir S2. According to the literature, artificial lift is an excellent means of well-scale optimization, including the gas lift, the electric submersible pump, the rod pump, the progressive cavity pump, the hydraulic pump, and gas injection by coiled tubing [19-23]. There are also several activation methods at the reservoir level, such as the infill well (deviated well, horizontal, vertical, etc.), secondary recovery (injection of water and gas into the reservoir), and tertiary recovery (thermal injection, micro-organisms). It would therefore be important to implement an appropriate optimization technique to improve the production at Well Y. This paper aims to optimize production at the scale of reservoir S1 and optimize production from reservoir S2 via the same well. To achieve this, the following objectives have been considered: (1) justify the optimization method; (2) develop the design and application of the optimization methods; and (3) improve production and draw up an economic assessment.

This article is organized into four sections: The first section deals with the introduction, the second section presents the data and tools, the third section presents the results obtained and finally the fourth section concludes the paper.

The tangent method is used to reach reservoir S2 located 12000 ft below reservoir S1 located at 10500 ft through Well Y to produce at the scale of reservoir S2. In this practice, a borehole with a 90° inclination is drilled to reach the reservoir S2, as shown in Figure 1.

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Figure 1. Diagram implementing the tangent method

In Figure 1, the inclination of Well Y starts at 8000 ft with an angle of 15° and becomes horizontal from 10900 ft (measure depth) with an inclination of 90°. The trajectory of the well remains constant until it reaches reservoir S2 at 12000 ft (measure depth). The results of the Well Y deviation are presented in Table 6.

Table 6. Deviation results of Well Y

Note: Horizont. refers to horizontal and Deg. means degree.

The design of Well Y after drilling has reached reservoir S2 is shown in Figure 2.

Figure 2 shows the positions of reservoirs S1 and S2 with their successive depths of 10500 ft and 12000 ft respectively, then the placement of the down hole equipment such as the packers 1 and 2, the sleeve, the well tubing, and finally the extension of the liner to reach the reservoir S2. The nodal analysis to see the productivity of reservoirs S1 and S2 is shown in Figure 3.

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Figure 2. Design of Well Y passing through reservoirs S1 and S2

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Figure 3. Nodal analysis of reservoirs S1 and S2 at Well Y

Figure 3 shows that the IPR2 curve (green curve) for reservoir S2 crosses the VLF curve (red curve) of Well Y, so reservoir S2 naturally produces 3581.55 STB/d at a pressure of 2980.45 psi. On the other hand, the IPR1 curve (orange curve) for reservoir S1 does not cross with the VLF curve (red curve) of Well Y, so reservoir S1 does not produce any hydrocarbons. The nodal analysis of reservoir S1 of Well Y is shown in Figure 4.

Figure 4 below shows that Well Y was initially unable to produce oil through reservoir S1 until it was activated by the jet pump, which is justified by the fact that the two curves VLF and IPR do not intersect.

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Figure 4. Nodal analysis of reservoir S1

3.1 Activation of Well Y at reservoir S1 by using the jet pump

The jet pump is used to activate Well Y at reservoir S1. The specificity of this pump allows hydrocarbons to be produced from both reservoirs S1 and S2. The reference jet pump has a nozzle diameter (Dj) of 0.265 inches and a throat diameter (Dt) of 0.996 inches with a fluid flow rate of 4091.23 STB/d. The characteristics of the jet pump are shown in Table 7.

Table 7. Characteristics of the jet pump used

After the activation of Well Y at reservoir scale S1, Table 8 gives the production characteristics.

Table 8. Productivity of reservoir S1 after using the jet pump

Once the first production zone is activated, a nodal analysis is carried out to check the reservoir's productivity.

Figure 5 shows the VLP curve (blue) and the IPR curve (red) rise as the tank can produce following its activation by jet pump. These curves increase because the pump can reduce the pressure at the bottom of the well, resulting in the well flowing at a value of 1124.9 STB/d with an oil flow rate of 449.9 STB/d. The production from reservoirs S1 and S2 takes place simultaneously through the same Well Y. This shows that the pressure at the bottom of the well rises to 3966.6 psi and the pressure at the top of the well to 434.2 psi as shown in Table 9.

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Figure 5. Nodal analysis of reservoir S1 in Well Y after activation

Table 9. Well productivity combining reservoirs S1 and S2

3.2 Infill well used to reach the reservoir S2 of the Well Y

After reaching reservoir S2 by infill well and activating reservoir S1 by jet pump from Well Y, the productivity of Well Y changed. The oil production rate increases to 4342.81 STB/d and a gas flow rate of 2.53 MMSCF/d with almost no water production, as shown in Table 10 and Figure 6.

Table 10. Productivity results for Well Y combining reservoirs S1 and S2

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Figure 6. Nodal analysis of the productivity of Well Y

Sensitivity analysis made it possible to vary the fluid injection pressure in the well in order to decide on the flow rate at which production should take place. The sensitivity tests were based on injection pressure at 2500 psi, 3000 psi, and 3500 psi. As shown in Table 11 and Figure 7 production from Well Y increases with increasing injection pressure.

Table 11. Results obtained for: (a) Injection pressure 2500 psi by jet pump, (b) Injection pressure 3000 psi by jet pump, and (c) 3500 psi injection pressure by jet pump

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Figure 7. Nodal analysis of fluid injection pressure variation

Production goes from 4365.34 STB/d at an injection pressure of 2500 psi, then when the injection pressure reaches 3000 psi, production rises to 4382.82 STB/d, and finally when the injection pressure reaches 3500 psi, production increases to 4404 STB/d. The well produces very little gas and almost no water. The variation in injection showed that as the injection rate increased, so did production. This allowed us to choose a jet pump injection rate of 3500 psi and a total production of 4404 STB/d from the two reservoirs through Well Y as shown in Figure 8.

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Figure 8. Nodal analysis of production from Well Y

3.3 Economic balance

The production target is estimated at a flow rate greater than or equal to 1000 STB/d because, at a flow rate of less than 1000 STB/d, production will no longer be sufficiently profitable. By using the exponential model, the production curve for Well Y is obtained and presented in Figure 9.

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Figure 9. Production prediction curve for Well Y

Figure 9 shows that from the tenth (10th) year onwards the production flow rate production rate falls below the requested production rate. Hence the productivity of Well Y is evaluated over a period of 10 years (0 to 9). Expenses are made up of CAPEX and OPEX as shown in Table 12, which summarises all project costs.

Table 12. Presentation of the various costs

Total expenditure over the ten years of production is estimated at 148.20 million. Evaluations have shown that over the ten years of production, the MW-1D well could produce a total volume of around 8.70 million barrels, and the price of a barrel on the international market is estimated at \$90, with total revenues estimated at 780.91 million over the ten years of production. The resulting cash flow is \$710926711.2 and the net cash flow obtained is \$476320896.5. The NPV obtained is \$140318586.1. The duration of the return on investment is evaluated at 0.72 years, which is equivalent to eight months, nineteen days, and four hours of production period.

The reliability of these findings is demonstrated by an economic balance sheet showcasing successful research results in oil well optimization using hybrid methods. By integrating techniques such as infill drilling and jet pump activation, operators can greatly improve production efficiency, lower costs, and prolong the life of wells. This strategy ultimately enhances profitability and promotes sustainable resource management in the oil sector. It is important to note that the selection of techniques is tailored to the specific characteristics of each well.