Production Performance Analysis and Reasonable Production Allocation for Carbonate Gas Reservoirs on the Right Bank of the Amu Darya

Carbonate gas reservoirs with edge and bottom water have significantly different characteristics and often contain well-developed fractures. Unreasonable production allocation for a single gas well tends to cause premature water breakthrough, making it more difficult to develop the gas reservoir efficiently. In this paper, taking the DT Gas Field in Area B on the right bank of the Amu Darya in Turkmenistan as an example, the production performance characteristics of the gas field are analyzed based on the previous geological study and understanding of the gas reservoir, and a comprehensive analysis of the stratigraphic subdivision, structural features, reservoir characteristics, well productivity, well test data, and single well production performance is performed. On this basis, a numerical simulation model for the gas field is established, and the reasonable production rates of gas wells are further optimized through history matching. The results show that (1) there are three types of pore spaces in the gas reservoir, namely, pores, dissolution vugs, and fractures. The development of dissolution vugs is consistent with that of fractures, and fractures are well-developed, which are structurally effective fractures. (2) Reservoir porosity ranges between 1.01% and 3.97%, with an average of 1.78%. Core permeability ranges from 0.0001 mD to 9.579 mD, with an average of 0.0129 mD. The reservoir is characterized by low porosity and low permeability. (3) The XVhp layer is the main pay zone. During the production test, the bottomhole flowing pressure was stable, the differential pressure was low, and the gas production was high, indicating that the reservoir has good petrophysical properties and high productivity. (4) Considering the feasibility of allocating reasonable gas production rates to delay the rise of edge water, the optimal production rate of Well DT-21 is 450–500 × 103 m3/d. Well DT-101D is a horizontal well; therefore, a slightly higher production rate, i.e., 500–550 × 103 m3/d, is allocated to this well. In addition, attention should be paid to the dynamic adjustment of allocated production rates to ensure stable production of the gas field.