Performance of Horizontal Wells in Gas Condensate Reservoirs: Hassi R'Mel Field, Algeria

Abstract

Hassi R'Mel Field is one of the biggest gas-condensate fields in the world. The southern area of this field, Module 02, has been depleted by vertical wells since 1979. Since 1981, water production has exceeded the allowed water limit. The salinity of the produced water is about 05 g/l, which is the maximum salinity allowed at the surface facilities. As a result, severe reservoir damage may have occurred. So the producing reservoir levels (C) were shut-in. The primary objective of this study is to investigate the performance of horizontal wells in a Sector-Model, to predict their behavior versus water production, and condensate recovery. To simulate the depletion processes, a compositional simulation is conducted to investigate the following phenomena in the case of horizontal and vertical wells:Water influx effects,Comparison of horizontal well drawdown pressure to that of vertical wells, andThe influence of the horizontal well length section and reservoir thickness on horizontal well productivity, and condensate recovery. A reservoir characterization is made, and a 3-Parameter Peng-Robinson equation of state (3-PR-EOS) is established to characterize the reservoir fluids. A 3-D Cartesian Sector Model was built for the zone of interest in order to predict the performance of horizontal wells and the different phenomena that can be present in retrograde gas-condensate reservoirs, and to analyze the most relevant reservoir parameters that affect horizontal wells performance. The obtained results showed that the use of horizontal wells is a proven technology for reducing water influx problems and improving condensate recovery. The condensate production of a horizontal well compared with that of a conventional vertical well can be increased by a factor of 1.30, owing to less condensate accumulation in the region of the producing well. Introduction Gas condensate reservoirs differ essentially in their behavior from conventional gas reservoirs, and the optimization of hydrocarbon recovery needs careful reservoir analysis, planning, and management. At the time of discovery, gas condensates are often found as a single-phase gas in the reservoir. However, as the production is carried out, there is an isothermal pressure decline and as the bottomhole pressure in a flowing well falls below the dew-point of the fluid, a liquid hydrocarbon phase is formed. Due to lower permeability to liquid and a high liquid-to-gas viscosity ratio, most of the condensed liquid in the reservoir is unrecoverable and constitutes the "condensate loss". Condensate loss is one of the greatest economical concerns since the condensate contains valuable intermediate and heavier components of the original fluid now trapped in the reservoir. The liquid keeps accumulating until the critical liquid saturation is reached. Once this liquid starts flowing, the flow of gas and liquid is subjected to the law of multiphase flow in porous media. For single-phase reservoirs, whether oil reservoirs or gas reservoirs, it has been well established in the literature that horizontal wells present significant advantages over vertical wells. Higher gas rate and increased liquid recovery are the main advantages that horizontal wells can offer. In horizontal wells, drawdown pressure is three to four times lower than vertical wells for the same flow rate. Therefore, there is less condensate deposited near the horizontal wellbore. This affects favorably the productivity of a gas condensate reservoir, as less blockage will occur in the skin zone. Literature review Gas condensate-related topics, such as well deliverability, well testing interpretation, gas-condensate inflow performance, and flow in reservoir in general, have been long-standing problems. From the literature, many studies have been conducted to predict the production behavior of a well in gas condensate reservoirs.

Single-Well Simulation for Horizontal Wells in Fractured Gas Condensate Reservoirs

“…Goode introduced another horizontal model, different from Daviau’s model in that it assumed reservoir anisotropy ( K x = K y = K z ), which adopts the Daviau model while considering the inconsistency of permeability in the horizontal and vertical directions. , Ozkan utilized the Green function to address the pressure response of horizontal wells in homogeneous and dual-porosity reservoirs with horizontal wells, employing no-flow boundaries above and below, while also considering anisotropic reservoirs. − Although Green functions and the Newman method had been developed by Gringarten and Ramey in 1973 to solve the problem of horizontal well unstable flow, their practical application has limitations, and it was not until 1991 that Ozkan and Raghavan introduced a comprehensive general solution based on Laplace variables. − These models and solutions have guided the development and solution of various models of horizontal wells and have provided abundant spatial analytic models for single and corresponding fast calculation methods, greatly enriching theoretical models. Marir studied the horizontal PTA method for dual-porosity sealed oil reservoirs, but there were certain flaws in the pressure response solution, leading to significant errors in later-stage pressure calculations . Hashemi proposed that the superposition principle could be used to consider the effects of wellbore storage and skin factor on pressure response .…”

“…Marir studied the horizontal PTA method for dual-porosity sealed oil reservoirs, but there were certain flaws in the pressure response solution, leading to significant errors in later-stage pressure calculations. 17 Hashemi proposed that the superposition principle could be used to consider the effects of wellbore storage and skin factor on pressure response. 18 Baqawi introduced analytical solutions for hydraulic fractured horizontal wells in naturally fractured reservoirs, significantly improving calculation accuracy.…”

A new and simple model for the prediction of horizontal well productivity in gas condensate reservoirs

“…There are only a few sensitivity studies which have discussed horizontal well performance in gas condensate reservoirs. Numerical simulations conducted by (Hashemi and Gringarten, 2005), (Dehane and Tiab, 2000), (Marir and Djebbar, 2006) and have all mainly been focused on the sensitivity of pertinent parameters on the performance of such wells.…”

Mitigation of the Effects of Condensate Banking: A Critical Review

“…Barnum et al (1995) reported that the higher the well capacity (well capacity is the kh product, where k is the rock permeability and h is the reservoir thickness, and is a measure of the reservoir quality), the less the impact of the condensate banking on the productivity of wells drilled in condensate reservoirs. Simulation and laboratory studies have indicated that condensate saturation around the wellbore may reach 70% (Marokane et al 2002).…”