Hu Yongle

Water production analysis and reservoir simulation of the Jilake gas condensate field

Abstract The development of the Jilake gas condensate field is dominated by production of old wells, with complication of well status, serious impact of edge-bottom water, and difficulty in development and adjustment. Through integration of formation water salinity analysis, color and density change of oil samples, diagnostic curve characteristic of modern production decline analysis and characteristic analysis of production water, the reason for water production is analyzed as follows: gas wells with low water production are affected by local connate water, while gas wells with high water production are influenced by the bottom-edge water. Integrated with domestic and overseas modeling of oil rim gas condensate reservoir, the fine geological model is built by Petrel geo-modeling software, and the approaches of non-equilibrium initialization and parameters initial value assignment is used to form the initialization model of the gas condensate field, in order to correctly portrait the oil rim and local connate water. On the basis of single-well water production analysis, the geological model is corrected through performance dynamic history match. The result provides a base and foundation for later development adjustment of this gas condensate field.

Flood pattern optimization of horizontal well injection

Abstract To optimize well spacing and injection rate in horizontal well flood pattern, formulae of the reasonable injection rate and well spacing are derived under fraction and no-fraction conditions respectively using filtration theory. The formulae take into account the fluid flow in low-permeability and thin reservoirs, and assume that horizontal well injection is rigid water driving. According to these formulae, the influencing factors of pressure loss on the horizontal section are diameter of casing pipe, production rate, and length of horizontal section. For a well with fixed casing diameter and horizontal section length, the influencing factors of pressure loss on horizontal section is only production or injection rate; for a reservoir, the influencing factors of maximal well space are length of horizontal section, oil production rate and water injection rate. The research results are applied in the Hade 4 thin layer sandstone reservoir of Tarim Oilfield. The designed flood pattern decreases injection pressure, augments injection, and keeps field pressure.

A model of production data analysis for horizontal wells

Abstract The production data analysis is one of hot spots of reservoir engineering recently, which combines conventional reservoir engineering analysis and modern well test analysis. Based on the theory of transient porous flow, the analysis provides a mathematical model, which not only reasonably predicts the production decline of oil or gas wells but also effectively evaluates the physical properties of reservoirs. Theoretical charts of Agarwal-Gardner production decline curves and derivative curves for common horizontal wells are presented by solving the transient 3D porous flow in the bounded reservoir. The Agarwal-Gardner curves can be divided into two stages: the derivatives are dispersed in the early transient decline stage and drawn to Arps harmonious decline in the late pseudo-steady state stage. The influence of vertical location of horizontal wells on production decline in the mid-long term is negligible in a homogenous reservoir. A field example illustrates that, given production data, the results in this article can be directly used to evaluate the reservoir characteristics and effectively forecast the long-term productivity for horizontal wells.

A novel interwell connectivity evaluation method for waterflooding reservoir using oil-water production performance

To address the issues that the existing connectivity evaluation models can only predict liquid production rate and the widely-used fractional-flow equations are not efficient to represent the water-producing characteristics in the whole water-cut variation period accurately, a novel connectivity evaluation method for waterflooding reservoir is established by using injection and production data. This developed model discretizes the reservoir into a series of production-based reservoir control volume. By coupling the producer-based capacitance-resistance model (CRMP) with a segmented water fraction-flow equation to obtain liquid production rate and water-cut, oil-water production data of each well can be further determined. Finally, the estimated parameters including connectivity, time constant and drainage volume of each producer are determined by history matching the measured production data with the newly developed Stochastic Simplex Approximate Gradient (StoSAG) optimization algorithm. Case studies show that, compared with the EnKF algorithm and the traditional projected gradient algorithm, the robustness of the ensemble-based StoSAG optimization procedure is higher. Moreover, the segmented water fractional-flow equation can achieve better dynamic matching and prediction effect of the measured production data than that of the single Koval fractional-flow model, which fully validate the reliability of the proposed interwell connectivity evaluation method and provides the theoretical basis for the actual applications in strongly-heterogeneous waterflooding reservoirs.