palash_panjaThe Department of Chemical Engineering is proud to announce the Dissertation Defense of Ph.D. candidate, Palash Panja, “Understanding Liquids Production From Shales,” on Monday, September 29th, 2014, 2-4pm in MEB 3235. Mr. Panja’s advisor is Dr. Milind Deo.

The growth of production from liquid shale plays has been phenomenal. However, the recoveries are low – of the order of 10% and more efficient methods of producing liquids are necessary. This research is aimed at understanding production performances involving complex interaction between phase behavior and flow in unconventional reservoirs like shales. Analytical evaluations requiring less computational effect, and comprehensive reservoir simulation methodologies were employed in this research. A new rapid semi-analytical forecast tool for transient state linear flow in ultra-low permeability (100 nD to 5000 nD) fractured reservoir was developed. The tool is useful for well inflow performance, condensate drop out and material balance calculations of condensate production in unconventional reservoirs.

Effects of individual parameter such as reservoir properties (matrix permeability, heterogeneity, rock compressibility and reservoir pressure), fluid properties (bubble point pressure and initial dissolved gas oil ratio), rock fluid properties (relative permeabilities), completion parameters (fracture spacing) and operating parameters (bottom hole pressure) on production oil were studied using reservoir simulations with appropriate number of grid blocks. The numbers of grid blocks necessary to achieve convergence of results were first obtained for different fluids types and reservoirs of differing permeabilities. The matrix permeability, initial reservoir pressure, fracture spacing were the most influencing factors in recoveries from gas- condensate as well as from oil reservoirs. Reservoir simulations were also used to understand the basic changes in production behavior in the near critical fluids as we transition from condensate to volatile oils. Liquid recovery was higher from condensate reservoir. Operating the well at higher flowing bottom hole pressure (FBHP) is preferable for low permeability (100 nD) reservoir and low FBHP for higher permeability (1000 nD) reservoir to recover more liquid. Production data, including Gas Oil Ratios (GOR) is valuable in assessing reservoir performance. A single characteristic factor affecting the produced gas oil ratio was found to be (1– Rsw/Rsb) (1–Pwf/Pb) /(1–Pwf/Pi) that predicts deviation of gas oil ratio from its initial value.

Effect of the interaction of parameters on recovery was examined using experimental design and response surface methodology. This study resulted in surrogate reservoir models for a quick assessment of production performance from ultra-low permeability black oil and condensate reservoirs. Risks of production performance and investment were quantified by preparing the probability density functions (PDF) of production outcomes and the hierarchy of the most significant input factors using the surrogate reservoir models for given input distributions. Average condensate recoveries from gas condensate reservoirs and oil recoveries from oil reservoirs were 16% and 13% respectively after 10 years of production. Net Present Value (NPV) of 25 million dollars was achieved from a well (cost 7.1 million dollars) with 18 fractures in 60 acre well spacing when economic limit of oil flow rate was reached. Abandonment time for well with 18 fractures in ultralow permeability oil reservoir was approximately 7 years.