## 6 Discussion  
The process of gas production in structurally complex fields has a number of peculiarities compared with the development of conventional reservoirs, which must be taken into account both in modelling the fields and in their operation [58; 59; 60]. Modelling a gas-bearing horizon as an object with distributed parameters in space and specified dynamic properties is proposed. This approach will make it possible to control the geometric dimensions of underbalance holes, the expansion of which leads to changes in reservoir composition and production complications, up to complete the watering of wells [61; 62]. There are financial costs associated with stopping and restarting production when a well is watered out. In some cases, when a well is watered out, production cannot be restarted, and a portion of the resource will remain unextracted. At the same time, the amount of unrecovered gas increases with the growth of unevenness of pressure distribution in the reservoir. The realization of the algorithm of distributed control action formation allows for the regulation of geometric parameters of underbalance funnels at structurally complex gas fields, preventing watering and related financial costs.  
The necessity to study the field as a spatially distributed object makes it necessary to apply advisory methods of controlling the processes occurring in the reservoir. For this purpose, methods of analysis and synthesis of DCS are applied. The nonlinear parabolic-type differential equation proposed by Academician [PERSON] is used as the main equation to describe the unsteady gas filtration in a porous medium. A model of the pressure distribution process based on this equation is constructed under certain assumptions. Specifically, the porosity and permeability coefficients are assumed to be constant, and the gas filtration follows the isothermal law.  
A mathematical and computer model of a nine-well field control system based on the provided data has been developed, with the possibility of obtaining transient plots before and after regulation. The developed closed-loop control system belongs to distributed control systems, the main advantage of which is the possibility of realising control actions not on a specific point but on the required area at once. A conventional PID controller takes into account only the mismatch at a given point when generating a control action,  
Figure 8: Transients taking into account the regulating influence.  
while a DHC takes into account both the mismatch at a given point and mismatches at neighbouring points, which allows for improving the dynamic characteristics of the control system. Compared with multidimensional concentrated systems, distributed systems are characterised by better transient quality (less over-regulation and duration) [63]. To simulate the potential for shock wave formation in the system, additional parameters need to be incorporated into the model.  
The improved algorithm of pressure field control is realized by calculating production well flow rates using Formula (31). This control algorithm can be practically implemented as a programme for a microcontroller controlling the flow rate. In this case, the initial data for the calculation of control actions are data on desired and current pressure drops in wells.  
The application of distributed control systems at structurally complex gas fields affects the efficiency of the gas production system as follows:  
1. Allows to regulate the geometric values of depression funnels and increases the gas and condensate recovery factor;
2. The possibility of realising control actions not on a specific point but on the required area as a whole will reduce the process of fluid backflow;
3. Allows to prevent premature watering and related financial costs.  
In practice, this system can be used to analyse individual well clusters and their behaviour during operation; when it is further expanded, it will provide the results of modelling the entire field.