This paper summarizes the results and learnings from the Autonomous Inflow Control Device (AICD) deployment and installation in multiple heavy oil fields in south Oman, allowing for swift utilization in other fields with similar characteristics. Those AICDs were mainly deployed and tested in those oil fields comprehensively, in horizontal producers, and the results were supported by rigorous lab tests was conducted to understand their behavior. This paper is a continuation of the work in reference [1]. In recent decades, horizontal drilling for producing wells became a widely known and used technology, this is due to the fact they improve the overall recovery, efficiency of production, drainage of the reservoir, as well as delay unwanted fluids (e.g. gas & water). However, this solution was not perfect, as due to highly fractured and heterogeneous reservoirs, premature water and gas production can and will take place, causing remaining oil to be bypassed, and hence, reducing the reservoir's recovery and eventually the profitability [2]. In south Sultanate of Oman, many fields have been developed with the use of the horizontal well technology, but together with its advantages, the geological nature of the formations and the physical properties of the produced fluids, have introduced important challenges regarding production optimization. One of the assets in question comprises of naturally fractured carbonate reservoirs drained through long horizontal open-hole completions. It has been developed with water flood and GOGD system. The main production optimization challenge faced for that asset is the fracture-dominated inflow, which leads to either high water or gas production. On the other hand, another asset where the trial took place comprises of shallow sandstone reservoirs of heavy oil, with strong bottom aquifers and high level of reservoir heterogeneities; fractures, faults and high permeability streaks are characteristic of these reservoirs. A horizontal well usually has a much higher capacity–as compared to a vertical well–for producing fluids at the same drawdown, hence, when talking on critical rates that do not disturb the oil-water-contact, horizontal wells will definitely have a higher critical rate than those of vertical wells, but even so, the capacity of moving fluids are bigger, causing faster movement of bottom water towards the horizontal well regardless [3]. Another field of the trial fields had produced heavy oil, with viscosities in the range of 600 cP to 1000 cP. The permeability is variable and in the range of 100mD to 10D. This makes the mobility ratio very favorable to water production. Some wells have started production with less than 10 % WC, but a sudden increase of WC has been observed up to above 90 %. Most of the wells have been completed with inflatable packers (EZIPs), creating 2 to 3 segments at the horizontal reservoir section. The AICD technology is suitable for being applied in this case of very low oil mobility and segments at the sand-face. The last trial field comprises of multi-stacked reservoirs, isolated by shale barriers, with production potential of oil from two main layers. The oil is light, ~ 42 API and 0.9 cp viscosity. Around 13 wells are closed-in due to various reasons including high water cut and low productivity. This field is producing since 1998 from 9 stacked reservoir zones-commingled, which provides a challenge to production allocation. Performing Production Logging Tests–PLTs-have not helped to improve the allocation issues. Water shut off is challenging when it comes to the point of deciding the zone required to be closed. Mechanical water shut off is an option to choke back the non-allocated water zones and allow more oil production. Although this field does not include horizontal wells, the total perforated length of the proposed well and the hydraulic natural isolation between the producing zones makes the application of the technology attractive for this field. An interventionless/wireless technology, which promotes uniform production along the entire length of a horizontal well, delaying the production of unwanted fluids (water or gas) from high productivity zones along the well path and promoting increased oil production from other compartments of the formation, would definitively represent a key aspect of the production optimization for these Petroleum Development Oman fields.
The field is located in the south of Sultanate of Oman and was discovered in 1980 The field produces from sandstone reservoirs a heavy crude with high viscosity (up to 2000 cP) value that contains no appreciable solution gas. Production is supported by a bottom active water drive aquifer. An unfavourable mobility contrast between the oil and formation water results in rapid water breakthrough and a large portion of a well's reserves are produced at high water cuts. The average economic limit of wells in the field is about 98% water cut. Thus, water management plays a key role in well economics. The new horizontal producer wells target is to drain by-passed oil with only 30 ~ 80 m spacing. Injectors are at the flank and are injecting deep into the aquifer. Water breakthrough occurs at high sand permeability and once happened; water will dominate well production due to unfavourable mobility ratio. Some of the new producer wells are completed with Wire-Wrapped Screen (WWS) – Stand Alone Screen, and swellable packers to isolate higher water-saturated zones. However, most of these wells start typically with a 60% water cut (BSW) or more and rapidly reach +90%. To overcome current reservoir/production challenges; The operator has used the latest Autonomous Inflow Control Device (AICD) Technology called Autonomous Inflow Control Valves (AICV). ICD's and previous generation Autonomous Inflow Control Devices (AICD) has shown in many cases increased oil production and higher recovery with better fluid influx balance along the well. However, neither ICD nor AICD can shut off the water production completely without well intervention. The AICV can restrict unwanted water significantly and autonomously. The AICV are based on different flow behaviour for laminar and turbulent flow that is utilized in a pilot flow to actuate a piston position to restrict unwanted fluids. The design with two parallel flow paths ensures the AICV is open for oil, and close for water autonomously. The AICV technology is based on Hagen-Poiseuille and Bernoulli's principles and is truly autonomous as it can identify the fluid flowing through it based on fluid properties such as viscosity, density and flowrate. For unwanted fluid such as water and Gas, AICV can generate enough force that will shut off the device if required. This makes it more robust than any other commercially available AICDs. AICV effect is reversible i.e. when the saturation of unwanted fluid (Sg or Sw) around the wellbore reduces, AICV will re-open for the oil production, thus draining all possible oil around the wellbore. In this paper, AICV performance will be discussed and comparative analysis with production performance of wells completed with WWS completed in the same reservoir will be presented. Based on the regular well testing and production analysis, it is evident that AICV technology has helped the operator in managing/shutting off the unwanted water production autonomously. This new AICV technology has the core application principles of ICD completions but the additional benefit of improved control/complete water shut-off without intervention; zero cost water shut-off operation and helps drain by-passed oil and thus maximizes recovery factors.
Several techniques have been applied to improve fluid conformance of injection wells to increase water flooding performance and eventually field oil recovery. Normal outflow control devices (OCDs) are effective solutions for this problem in reservoirs with static properties, however, they fail in reservoirs with complex/dynamic properties including fractures. There, the continuously increasing contrast in the injectivity of a section with the fractures compared to the rest of the well causes diverting a great portion of the injected fluid into the thief zone thus creating short-circuit to the nearby producer wells. This paper summarizes the integrated technical learnings from the successful application of the installation of the first Autonomous Outflow Control (AOCD) technology in a new long horizontal injector well. It shows the result of extending this technology to other injectors in both water and polymer phases in the field, it details the facts and observations and the insights the multidisciplinary authors have captured. This autonomously reactive control on the injection fluid conformance resulted in an increased sweep and ultimate oil recovery while reducing the total volume of injected fluid.
The multidisciplinary Authors summarize the lessons learned from stimulating a long horizontal Polymer Injection well with a Hoisting Unit; the main objective was to reduce the associated cost as compared to a Coiled Conventional Tubing (CCT) Unit, but achieving the same or even improved results. The details procedures for conducting this type of job is summarized in this paper. The well was completed with a smart completion, creating four distinguished zones, Earlier, bullheading approach was carried out, but later on when the smart completion failed, it was necessary to stimulate with a CCT to cover all the different zones in the long well section. This has caused a sharp increase in the price of the job. Hence, a trial has been carried out utilizing a Hoist, with improved acid recipe that is cheaper and better in performance as compared to earlier. The detailed procedure for conducting this type of job is summarized in this paper The tables show the injectivity test result in three stages, in the Hoist and the CCT approach the result shows a good improvement after main treatment and a success of the trial with Hoist as compared to CCT. This has proven to be economically viable and unlocked huge cost savings for all future stimulation jobs. A 50% reduction in the total cost is observed. This work has concluded a successful methodology in the utilization of a hoist in performing multi-stage stimulation in long horizontal wells. Very encouraging results have been observed and the suggested method is highly recommended, further trials will continue to be done with other wells The authors believe the learnings from these trials are of great benefit and will add to the state of knowledge of the industry relating to stimulating long horizontal wells
The multidisciplinary authors have summarized the results from the Autonomous Inflow Control Device (AICD) deployment in multiple oil fields, and presented it in this paper as a practice worth replication in a similar heavy oil environment, due its many benefits in optimizing field development. AICDs have been tested mainly in labs and controlled environments with few comprehensive field trials. This paper will form the basis for that which will add to the state of knowledge in the industry. The AICD technology was piloted in few wells of these fields. It comprises of mechanical devices installed with the sand face completion, which react in real time to the properties of the flowing fluids, decreasing/delaying the water influx (or gas if it would be the case) from high productivity zones, promoting increased oil production from other compartments of the formation, therefore, equalizing the drawdown along the horizontal section of the well and performing a dynamic water shut-off operation. No cables are required, as the devices work on the basis of viscosity and density difference between the oil and the water. The AICD-completed wells showed initial water cut in the range 1% to 2%. Which has reduced significantly in comparison to nearby analogues. The initial net oil rate resulted to be more than 2 times of the expected one, with an acceleration of ~10,000 bbls of net oil during the first month. After the initial production period, the technology is still delaying the aggressive water cut development usually observed in these fields, having provided 2 times the expected net oil rate during the first 3 months, with an acceleration of approximately 20,000 bbls of net oil over this period. It has been concluded that the application of the technology is successful and will be deployed as a baseline in all future horizontal wells drilled.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.