Determination of Reservoir Properties and Heterogeneity through Pressure Transient Analysis for a Clastic Gas Reservoir

Abstract

A clastic gas reservoir, have been characterized of being unconsolidated in nature, as well as its complexity and heterogeneity. Regarding to the ability to transmit fluids, this reservoir is predominantly tight with a wide variation in the permeability range, which confirms its heterogeneity. The depositional environment interpretation suggests the presence of channels running from West to East direction with kind of limited lateral extension. In terms of well completion strategy, most of the wells have been proppant fractured to produce at sustainable rates. Pressure transient analysis (PTA) has been applied extensively to better characterize and understand the reservoir behavior, well performance and to obtain significant properties of the reservoir. The challenges of this work consisted of performing a critical review of the existing PTA to identify some common behaviors or general trends in the pressure response. Considering the PTA have assessed the same reservoir and that several wells have been completed with similar completion techniques was expected finding similar pressure response behaviors. This paper presents different cases that have been analyzed through PTA, summarizing common trends, in terms of reservoir behavior and well response that have been observed during the study. The outputs of this study were used as inputs for the simulation reservoir models to narrow the uncertainty in some reservoir and wellbore properties and as inputs for the static model construction to better understand or confirm geological assumptions. The results of the PTA interpretation also helped to successfully drill newer wells away from any geological complexity and achieved the planned target of gas rates.

Effect of Geological Heterogeneity on the Production Performance of a Multifractured Horizontal Well in Tight Gas Reservoirs

“…Compared to the analytical and semianalytical methods, the numerical simulation methods are more convenient to study the transient flow and production problems in both homogeneous and heterogeneous reservoirs [19][20][21][22][23][24][25][26][27][28][29]. Yu et al [19] discussed the effect of different fracture half-length combinations on the multifractured gas well production performance.…”

“…It is found that the measurement of non-Darcy flow character, the establishment of horizontal heterogeneous reservoir models, the induced stress model, and the design of operation parameters are the key steps to realize the optimization strategy. Guizada et al [26] made full use of the pressure transient analysis to identify and interpret the reservoir properties. Subsequently, a large number of interpretation results were used as input variables in the simulation.…”

Application of Pressure Transient Analysis in Highly Deviated Reservoir

“…The quantification of the change in porosity and permeability due to a sudden increase in pressure drawdowns can be used where compaction is a significant concern [4]. Thus, the results of the PTA interpretation enabled drilling newer wells away from any geological complexity and achieved the planned target [5]. However, when relying on a single PTA outcome for key subsurface parameters can be demonstrated, the interpreted subsurface properties showed a strong dependence on the input parameter range…”