Abstract The purpose of this paper is to present a case study of a pioneering step taken in restoring well integrity for workover rig intervention through the utilization of instrumented coiled tubing (CT) and through-tubing inflatable and retrievable packer (TTIRP) in South Kuwait Field. In this particular instance, mechanical constraints at the christmas tree tubing hanger hindered the ability of the operator to install the blowout preventer (BOP) of the workover rig through conventional means. As a result, a custom-fit approach was implemented to enable the required number of pressure barriers to intervene the well. The intervention approach employed the use of instrumented CT for barrier restoration, well killing and temporary well suspension. CT real-time downhole telemetry was utilized to ensure accurate placement and setting of the TTIRP within the production tubing. Once the packer integrity was pressure tested in both directions, CT was disconnected, and a sand plug followed by an acid soluble cement plug were placed on top of the TTIRP. Upon confirmation of cement plug integrity, the workover rig was utilized to install the BOP for intervention. The instrumented CT was then rigged up and run back-in-hole to clear the cement plug, circulate the sand out, and retrieve the TTIRP to the surface. The candidate well where this innovative intervention workflow was implemented had a maximum potential wellhead pressure of nearly 1,500 psi and a plug-back true depth (PBTD) of 4,000 ft. The well was completed with 3 ½-in. production tubing set close to 3,500 ft MD and 8 5/8-in. casing until PBTD. An e-line through-tubing puncher was carried out in the production tubing before the first CT run to enable circulation of killing fluid. The TTIRP setting depth was conditioned via instrumented CT and high-pressure rotary jetting tool, resulting in a shut-in wellhead pressure near zero psi. The results of this innovative intervention workflow were substantial, with an estimated saving of 195,000- bbl in deferred production (as the well was shut-in for at least 10 months). The lessons learned from this case study can now serve as a reference for operators in the Middle East with wells that present similar challenges.
Thermal oil recovery processes are contributors to the world’s oil daily production. The input of thermal energy into hydrocarbon reservoirs reduces oil viscosity and improves mobilization and production of heavy oils. Thermal energy might be introduced to subsurface formations through heat carrying agents such as hot water or steam. These mechanisms are important thermal recovery techniques which are currently implemented in many oil fields to increase oil recovery efficiency. Evaluating the degree of heat involvement in improving oil recovery from high viscosity oil reservoirs is a crucial issue to optimize the economics of thermal injection projects. Therefore, the performance of thermal recovery processes should be investigated under various reservoir and/or surface conditions prior to field application. In this work, the effects of several reservoir/operational parameters on the performance of hot water and steam flooding in a high viscosity Middle Eastern reservoir are investigated by numerical means. The objective of this study is to highlight the relationships between heat injection and oil recovery factor under various reservoir/operational conditions. These conditions include the arrangement of injection and production wells, reservoir lateral dimensions, injection rate, temperature and oil viscosity relationship, and reservoir thickness. The results are presented in terms of oil recovery factor versus cumulative heat injected per unit reservoir volume. The results indicate that the investigated parameters have various degrees of influence on hot water and steam flooding performance.
The main objectives of this project are to quantify the changes in fracture porosity and multi-phase transport properties as a function of confining stress. These changes will be integrated into conceptual and numerical models that will improve our ability to predict and optimize fluid transport in fractured system. This report details our progress on: (1) developing the direct experimental measurements of fracture aperture and topology using high-resolution x-ray micro-tomography, (2) modeling of fracture permeability in the presence of asperities and confining stress, and (3) simulation of two-phase fluid flow in a fracture and a layered matrix. The three-dimensional surface that describes the large-scale structure of the fracture in the porous medium can be determined using x-ray micro-tomography with significant accuracy. The distribution of fracture aperture is a difficult issue that we are studying and developing methods of quantification. The difficulties are both numerical and conceptual. Numerically, the three-dimensional data sets include millions, and sometimes, billions of points, and pose a computational challenge. The conceptual difficulties derive from the rough nature of the fracture surfaces, and the heterogeneous nature of the rock matrix. However, the high-resolution obtained by the imaging system provides us a much needed measuring environment on rock samples that are subjected to simultaneous fluid flow and confining stress. The absolute permeability of a fracture depends on the behavior of the asperities that keep it open. A model is being developed that predicts the permeability and average aperture of a fracture as a function of time under steady flow of water including the pressure solution at the asperity contact points. Several two-phase flow experiments in the presence of a fracture tip were performed in the past. At the present time, we are developing an inverse process using a simulation model to understand the fluid flow patterns in the presence of a fracture, and the interactions between fluid flow in the fracture and the adjacent matrix. Preliminary results demonstrate that the flow patterns are significantly impacted by the presence of the fracture. Bypassing is quantified and we expect to be able to extract from the modeling the distribution of properties in the fracture and the adjacent matrix.
Abstract The applications of Enhanced Oil Recovery (EOR) techniques are encouraged by the growing demand for oil. Optimizing oil production from current resources is becoming the main strategy for many oil producing companies around the world. Among EOR processes, polymer flooding is an attractive option in many reservoirs. The objective of polymer flooding is to control water mobility inside the reservoir to favor higher oil recovery. Several design parameters are critical for the success of polymer flooding applications. The salinity of formation water is one of the challenges which impose a limitation on polymer flood applicability. In Kuwait, most of oil reservoirs are high water salinity reservoirs. Therefore, improving the performance of polymer floods under high water salinity conditions may unlock these resources which can have enormous positive effects on oil reserves. One way for this improvement is to condition these reservoirs by injecting a slug of water (preflush), ahead of polymer, with specific characteristics. In this work, lab experiments were conducted in which the effects of several design parameters of polymer flooding are investigated under high water salinity conditions. Design parameters include preflush salinity, preflush viscosity and preflush slug size. The results suggest these parameters correlate differently with oil recovery factor. Introduction With the current growing demand for oil led by major energy consuming countries such as China and India, securing new oil resources is a critical challenge for the oil industry. Adding new oil reserves can be achieved by finding new discoveries or by optimizing oil production from current resources. The cost associated with the first option is significant since the new resources are expected to occur in challenging environments such as deep formations or deep water. Therefore, the need to optimize oil production from current resources through Enhanced Oil Recovery (EOR) techniques is a main strategy for many oil producers. EOR processes are generally classified as thermal, miscible, or chemical processes. Reservoir's rock and fluid properties and economics dictate the choice of which EOR process to follow. Thermal methods are mainly used in heavy oil reservoirs; whereas miscible processes are suitable for lower viscosity oils. Chemical EOR processes are used to reduce reservoir forces responsible for oil entrapment. There are different versions of chemical processes depending on the type of fluid used such as: polymer, alkaline, and surfactant.
Abstract The Mauddud formation in Bahrah field located in north Kuwait is a low permeability carbonate formation with moderate to high oil viscosity. As the field development phase progressed, the field started suffering from production decline and reservoir pressure depletion due to lack of pressure maintenance. This work presents the entire process of identification of a potential candidate for multistage hydraulic re-stimulation including operational preparations, re-execution, and analysis of post-treatment results. The interest in restimulating wells has been driven by multiple factors—the desire to arrest the steep decline curves of wells, to fully drain formation and to increase the EUR of the well through achieving additional stimulated reservoir along the lateral completions. The development strategy in Bahrah field was to drill horizontal wells and complete them with multistage stimulation sleeves and were operated by a ball-drop system from the surface. There are several reasons to consider restimulating a well, and without properly assessing the goal of a particular restimulation treatment, it can be difficult to discern which candidate wells are best positioned for economic success. After candidate selection, developing a solution phase that will accomplish the treatment's goal and overcome operational challenges to selectively close sleeves and open target sleeves, and to confirm and diagnose such functionality, but also address reservoir challenges such as restimulation of hydraulically fractured depleted and low-pressure reservoirs is one of the most important challenges. The Nitrogen (N2) Foamed acid, used in this methodology, is a finely dispersed mixture of nitrogen gas bubbles within hydrochloric acid liquid which increases the volume of the active acid, improves penetration, and diverts fluid from high permeability zones into low permeability zones. This in turn, enables to control fluid loss, maximize conductivity, and provide gas expansion to assist flowback. This paper summarizes the candidate selection criteria, first application of restimulation design in Kuwait, operational procedures, diagnostics tools, well clean-up and production performance aspects of the N2 foam restimulation treatment. Success of this N2 foam restimulation technique is crucial for Bahrah field to overcome production decline and reservoir pressure depletion and effectively stimulate Mauddud formation, increasing the stimulated reservoir volume to continue rising field production capacity. Based on the comparative valuation completed on the Bahrah wells, the use of energized fluids is shown to create significantly improved well performance over those wells fractured with non-energized fluids. Though the treatment costs for the energized fracture treatments were seen to be higher, the value of this incremental recovery surpasses the supplementary cost with no additional risk. Besides, there is potential to reduce the fracturing fluid liquid volumes with using N2 Foam treatments, thereby improving production while also minimizing ecological impact. The first application of this methodology is tuned to focus on the challenges of well procedures, formation technical complications, high-operational economics, and high potential from this depleted reservoir.
Using natural fibres in civil engineering is the aim of many industrial and academics sectors to overcome the impact of synthetic fibres on environments. One of the potential applications of natural fibres composites is to be implemented in insulation components. Thermal behaviour of polymer composites based on natural fibres is recent ongoing research. In this article, thermal characteristics of sisal fibre reinforced epoxy composites are evaluated for treated and untreated fibres considering different volume fractions of 0–30%. The results revealed that the increase in the fibre volume fraction increased the insulation performance of the composites for both treated and untreated fibres. More than 200% insulation rate was achieved at the volume fraction of 20% of treated sisal fibres. Untreated fibres showed about 400% insulation rate; however, it is not recommended to use untreated fibres from mechanical point of view. The results indicated that there is potential of using the developed composites for insulation purposes.
