Rouzbeh Ghanbarnezhad Moghanloo

Integrated Investigation of Dynamic Drainage Volume and Inflow Performance Relationship (Transient IPR) to Optimize Multistage Fractured Horizontal Wells in Tight/Shale Formations

This study presents an integrated approach to evaluate the efficiency of fracturing stimulation and predict well production performance. As the pressure disturbance propagates throughout the reservoir during long-time transient flow regimes, it will shape an expanding drainage volume. A macroscopic “compressible tank model (CTM)” using weak (integral) form of mass balance equation is derived to relate dynamic drainage volume (DDV) and average reservoir pressure to production history in extremely shale reservoirs. Fluids and rock compressibility, desorption parameters (for shale or coal gas), and production rates control the speed at which the boundaries advance. After the changes of average reservoir pressure within the expanding drainage volume are obtained, a new empirical inflow performance relationship (transient IPR) correlation is proposed to describe well performance during long transient flow periods in shale reservoirs. This new empirical correlation shows better match performance with field data than that of conventional Vogel-type IPR curves. The integrated approach of both CTM model and transient IPR correlation is used to determine and predict the optimal fracturing spacing and the size of horizontal section for few wells from one of shale oil plays in U.S. The results suggest the existence of optimal fracture spacing and horizontal well length for multistage fractured horizontal wells in shale oil reservoirs. In practice, this paper not only provides an insight in understanding the long transient flow production characteristics of shale reservoirs using concept of expanding drainage volume. Neither methods require comprehensive inputs for the strong form (differential) nor any prior knowledge about the sophisticated shale reservoir features (shape, size, etc.), the ultimate drainage volume, the ultimate recovery, optimal fracture spacing, and the length of horizontal section for each well can also be easily obtained by this new integrated analytical method.

Formation Damage by Organic Deposition

Abstract Despite the myriad of published literature on asphaltene deposition in porous media, true understanding of its characterization is still lacking. A literature review of the state of the art in asphaltene research is provided, examples and theories involved in asphaltene deposition are expounded, and a discussion about the validation and critiques is conducted in this chapter. This work takes a detailed look at asphaltene deposition within the porous media, and provides a novel technique in the characterization of the deposition problem. Historically, permeability reduction has been attributed to pore volume change due to surface deposition. However, pore throats will also be blocked through retainment of particles that will potentially lead to severe conductivity and permeability reduction even when a large fraction of total pore volume still remains intact. Here we evaluate permeability reduction as a function of the combined effects of surface deposition and interconnectivity loss due to pore blockage. The effects of pore surface deposition and pore blockage are evaluated based on published experimental data on limestone, sandstone, and carbonate rock samples. We observed that surface deposition seems to be dominant in limestone due to the large pore throat size compared to the particle size. In sandstone samples, both the surface deposition and pore throat plugging seem to contribute fairly equally to permeability reduction. In the case of dolomite however, the pore blockage seems to be dominant, which results in an almost instantaneous sharp decrease in sample permeability. This work sheds some light on the inadequacies of the deposition model, and provides a solution for better future modeling work of asphaltene deposition in the near wellbore reservoir zones.

A Special Focus on Formation Damage in Unconventional Reservoirs

Abstract As shale plays maintain their role as one of the main energy resources in the United States, production sustainability remains the key decision-making parameter for investors. Multistage fracturing treatment has made shale resources economically viable; however, the success of production operations depends on the quality of the created fracture network and matrix deliverability around the wellbore. The sharp decline in production usually observed is strongly affected and controlled by a reduction of fracture conductivity and formation deliverability owing to formation-damage mechanisms. Major damaging parameters resulting in fracture conductivity loss such as proppant transport and placement, proppant embedment and crushing, fine migration and plugging, gelling damage, and multiphase flow are analyzed. Moreover, the severe reduction in reservoir permeability is explained by the combination of two main phenomena: (1) Pore shrinkage and (2) connectivity loss due to bond breakage between interconnected pores. We use fractal and percolation theories to analyze the effects of both pore shrinkage and connectivity loss on intrinsic permeability reduction. This study summarizes the vital considerations and important parameters that are crucial to know in order to design successful hydraulic fracture treatments and improve productivity in tight formations.

Using Nanofluids to Control Fines Migration in Porous Systems

Abstract The main objectives of this chapter are as follows: (1) to review the laboratory experiments and field cases providing proof of concept for the effectiveness of nanoparticles utilization to control fines migration; (2) to develop mathematical foundations to evaluate the success of nanoparticles to control fines migration in both linear and radial flow system; (3) to compare the performance of two different approaches of nanoparticles utilization (coinjection and pretreatment) to control fines migration; (4) to evaluate nanofluid utilization to reduce fines migration in porous media saturated with two immiscible fluids; and (5) to investigate the feasibility of combining nanofluids with low-salinity waterflooding to improve production performance. To accomplish the abovementioned objectives, the following topics are evaluated: (1) nanoparticles adsorption, detachment, and straining behaviors and their effects on permeability damage are quantified using both mathematical models and experimental works; (2) the positive contributions of nanoparticles to mitigate fines migration are characterized by the enhancement of maximum retention concentration of fine particles onto rock grains through defining the mutual reactions among nanoparticles, fines, and rock grains; (3) theoretical evaluation is summarized for the effectiveness of nanoparticles to mitigate fines migration in single-phase water and two-phase oil and water flow using different approaches of nanoparticles utilization to control fines migration: coinjection of nanoparticles with fines suspension, and precoating of porous medium with nanoparticles prior to fines injection; (4) an axisymmetric radial flow is introduced to evaluate the mobility-control improvement associated with fines migration, and optimize the nanofluid treatment radius for the purpose of improving the performance of low-salinity waterflooding.

Enhance horizontal well performance by optimising multistage hydraulic fracture and water flooding

In naturally fractured tight oil reservoirs, the combination of multistage fractured horizontal well and water flooding could enhance production rate and ultimate recovery. This paper introduces the combination of composite double porosity model and local refinement Technology to optimise the performance of multistage fractured horizontal well. In base of the non-uniform distributions of natural fractures, we adopt different shape factors of dual-porosity model to distinguish the stimulated area and unstimulated zone. By comparing with the performance of different SRV shapes, the optimal design of SRV is irregular shape with scattered distribution of fracture length at different locations of wellbore. The optimal size of SRV, cluster spacing, width of SRV are presented. In addition, in seven-spot injection/production well pattern, this paper presents the optimisation of multistage fractured horizontal well orientation with different SRV shapes (single-spindle and double-spindle), and well spacing. [Received: May 18, 2015; Accepted: March 1, 2016]