Applying high pressure to tight formations such as shale involves the use of a fluid, proppant, and additives to either generate new cracks or expand existing ones. This process enables hydrocarbons to flow more efficiently into the wellbore and, ultimately, to surface facilities.

Commonly known as "fracking," hydraulic fracturing is primarily employed for hydrocarbon production. The proppant within the hydraulic fracturing fluid ensures that fractures, once created, remain open, allowing hydrocarbons to gradually escape from the tight formation. The additives consist of various chemical components, each serving a specific role in enhancing the fluid's suitability for a successful hydraulic fracturing process [1].

The following are some of the reasons for conducting hydraulic fracturing: Wellbore protection to prevent damage that reduces productivity. Damage near the wellbore results from drilling debris infiltrating the formation and the ineffectiveness of drilling fluids to interact chemically with the target formation. This can be rectified through chemical means, such as hydraulic fracturing or matrix treatments, to restore conductivity between the wellbore and the formation. The goal of optimizing the hydraulic fracturing process is to maximize gas and oil production by increasing the extent of cracked reservoir rock. The optimization is based on a model of fracture propagation in elastic media induced by viscous fluid injection. Input parameters include the surface of the cavity in an infinite elastic medium, the fluid pressure initiating and propagating the fracture, and the properties of the elastic medium. The output properties of the model include fracture surface, fracture width distribution, and fracture front propagation speed. Solving the direct problem of fracture propagation involves calculating these output characteristics from the input parameters, enabling predictions of fracture behavior, hydrocarbon extraction, costs, and more. To enhance hydraulic fracturing treatment, the ratio of fracture length to drainage radius must be optimized. By estimating the flow rate over time based on fracture length and drainage radius, ideal fracture length and drainage radius can be determined for blanket reservoirs [2-5]. In lenticular reservoirs, the drainage radius is a constant value, often informed by geological studies of the region. Once this likely drainage radius is obtained, engineers can optimize propped fracture half-length by adjusting the ratio.

For optimal performance in a fracture stimulation program, two critical characteristics are a suitable fracture half-length and fracture conductivity.

Since,

     -------- [1]

Where,

F_cd ≡ Fracture conductivity 

k_f ≡ Fracture permeability

W ≡ Conductive fracture width

k ≡ Formation permeability

L_f ≡ Conductive fracture single wing length

Post-fracture temperature logs play a crucial role in assessing fracture height following hydraulic fracturing [6]. The procedure involves the following steps: Prefracture Temperature Profile Determination: A pre-fracture temperature log is run to establish the temperature gradient within the reservoir formation prior to hydraulic fracturing. This baseline temperature data is essential for subsequent analysis.

Postfracture Temperature Logging: After the hydraulic fracturing stimulation process, at least two post-fracture temperature logs are conducted. These measurements capture the changes in temperature distribution resulting from the fracturing.

Heat Transfer Mechanisms: Heat transfer in the surrounding rock layers occurs primarily through conduction. However, in the fractured pay zone, heat transfer is predominantly driven by convection, which is more efficient in transporting thermal energy.

Interpretation of Temperature Logs: The interpretation of these temperature logs involves analyzing the recorded temperature data. An important aspect to note is the presence of a temperature anomaly. This anomaly arises from the varying rates of temperature recovery in the fractured zone after the hydraulic fracturing process.

The detection of this temperature anomaly is significant as it indicates the location and extent of the fractured zone. By comparing the post-fracture temperature logs to the pre-fracture temperature profile, the engineers and geologists can identify the region where the hydraulic fracturing has created fractures or altered the thermal behavior of the formation [7,8]. This information is invaluable for assessing the success of the fracturing operation and understanding the resulting changes in the reservoir.

This study was conducted on an unconventional reservoir with a permeability range of 5-13 millidarcies (mD). The primary objective of this research project was to determine the optimal hydraulic fracture length and fracture width for a specified well.

Sensitivity analysis was performed on the hydraulic fracture length. In the first scenario, where the horizontal section's length was 150 meters, multiple simulations were carried out with varying hydraulic fracture lengths. The results were then compared based on total gas production. It was determined that a hydraulic fracture length of 125 meters yielded the best results for this well.

In the second scenario, with a horizontal section length of 200 meters, a similar approach was employed. Multiple simulations were conducted by adjusting the hydraulic fracture length, and the outcomes were compared in terms of total gas production [9-12]. Once again, it was found that a hydraulic fracture length of 125 meters produced the optimal results for this well.

These findings suggest that, regardless of the length of the horizontal section, a hydraulic fracture length of 125 meters appears to be the most effective choice in terms of maximizing gas production for the defined well in this unconventional reservoir.

Table 1: The impact of hydraulic fracturing length range of 50-150 meters to the well production.

Figure 1: The impact of hydraulic fracturing length range of 50-150 meters to the well production.

Table 2: The impact of hydraulic fracturing length range of 100-200 meters to the well production.

Figure 2. The impact of hydraulic fracturing length range of 50-150 meters to the well production.

The study has shown that having the longest possible fracture length doesn't necessarily result in the highest production. Instead, the research has determined that, for this particular well, the optimal fracture length is 125 meters. Following this, the researchers conducted reservoir simulations with various hydraulic fracture widths while keeping the hydraulic fracture length constant at 125 meters. This step aims to further refine the hydraulic fracturing design by examining how different fracture widths can affect production. In essence, the study emphasizes the importance of optimizing both fracture length and fracture width to achieve the best production results for this specific well. It suggests that, in this case, the ideal configuration involves a 125-meter fracture length, but the study seeks to determine the optimal fracture width within that length to maximize production.

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