Modification of the Calculation Method for Dynamic Reserves in Tight Sandstone Gas Reservoirs

Abstract

The determination of dynamic reserves is important for tight sandstone gas reservoirs in production. Based on the geological and gas data of the Yan’an gas field, the influence of pressure on the properties of natural gas is studied by mathematical methods. At the same time, the modified flowing material balance equation is established considering the changes in gas viscosity and compressibility. The result shows that (1) the viscosity of natural gas increases rapidly with pressure; (2) the deviation factor decreases with pressure (P < 15 MPa) and then increases (P > 15 MPa) with temperature; (3) the compressibility decreases rapidly with pressure and increases with temperature; (4) compared with the results of the material balance method, the average error of the flowing material balance method is 33.95%, and the accuracy of the modified flowing material balance method is higher with an average error of 1.25%; and (5) a large change in the production will affect the accuracy of the modified flowing material balance method, especially a shut-in for a long time before the pressure drop production is calculated at a certain time, so data points that are relatively consistent should be selected as far as possible to calculate the dynamic reserves. The findings of this study can help in the accurate evaluation of dynamic reserves of the tight gas reservoir in the Yan’an gas field and are an important guide for the formulation of a rational plan for the gas reservoir and its economic and efficient development.

Study on reasonable production allocation method of tight sandstone gas reservoir—A case of XX block in ordos basin

“…Ordos basin is a large sedimentary basin with multi-cycle evolution and multi-sedimentary types and it is about 25 × 10 4 km 2 (Li et al, 2014;He et al, 2021a). The internal structure of the basin is relatively simple, without secondary structure, and the tertiary structure is dominated by nasal uplift (Huang et al, 2020;Kazemi and Ghaedi, 2020).…”

A Dynamic Reserve Evaluation Method for an Ultra-Deep Fractured Tight Sandstone Gas Reservoir

“…Currently, the methods for estimating the dynamic reserves of gas reservoirs can be broadly categorized into three types: material balance methods, modern decline curve methods, and well-testing-related methods [10][11][12]. However, the geological conditions of ultra-deep fractured tight sandstone gas reservoirs differ significantly from conventional gas reservoirs, leading to substantial errors and uncertainties when applying conventional dynamic reserve evaluation methods to the assessment of dynamic reserves in ultra-deep fractured tight sandstone gas reservoirs [13][14][15]. Therefore, this paper proposes an alternative formulation to estimate the dynamic reserves of fractured tight sandstone gas reservoirs.…”