Analysis of the financial assurance problem for decommissioning of oil and gas wells and facilities

The harmful effects of oil and gas projects on the environment are not limited to the production period. Unlike operating production facilities, control over the state of abandoned wells and fields falls on the state. In the Russian Federation, the obligations of subsoil user companies to properly perform decommissioning operations are not legally regulated and financially secured. Based on world experience, the paper analyzes the most common schemes for formation and accounting of financial assurance for decommissioning operations and examines the state of legislative regulation on this problem in Russia and the world. It presents recommendations on state regulation to guarantee full completion of decommissioning operations by subsoil users, improve their quality and monitor the environmental safety of abandoned wells.

Geo-Thermo-Mechanical Modeling of Pre-Drilled Wellbores to Extract Geothermal Energy from Subsurface to Produce Cleaner Energy for United Arab Emirates

The middle eastern countries including United Arab Emirates (UAE) have enjoyed the energy production from hydrocarbon resource for a very long period. Indeed, now various countries in this region has shifted to alternative resources of power generation with cheaper and cleaner sources. Geothermal is the top of the list among those sources. Therefore, this study presents an ultimate model converting abandoned oil and gas wells into subsurface geothermal recovery points. Fundamentally, this study offers a geo-thermo-mechanical model of abandoned wellbore which can help in developing an optimistic geothermal energy not only from subsurface thermal reserve but also from abandoned casing and pipes installed in Wellbores. In this approach the source of heat is thermally active rock formations and the metallic pipes that are present in wellbores drilled through hot dry rocks. In the model the already drilled wells are incorporated as medium of heat flow in which water in injected and brought back to surface along with thermal impact. The results of this study revealed that, at the depth of 6000 m of high temperature wellbore the temperature is above 85°C and at this temperature the metallic casings further rise the reserve temperature thus the conversion of water into steam can be processed easily. Moreover, at high depths the stability of wellbore is also issue in high temperature formation, so mechanical model suggests that injection of water and conversion into steam in already cased wellbore can sustain up to 6 MPa stress at around 100C. Thus, the geo-thermo-mechanical model of wellbore will illustrate the possibility of converting water into steam and it will also reveal the average amount of heat that can be generated from a single well. henceforth, the thermal recovery from abandoned wells of UAE is best fit solution for clean energy. The abandoned wells are used as conduit to transport heat energy from subsurface by using water as transport medium, as water at surface temperature is injected in those wellbores and let thermal energy convert that water into steam. Later the steam is returned to surface and used as fuel in turbines or generators.

Casing While Drilling Successfully Implemented for the First Time in High Risk Area of the Bahrain Field

One known risk of the Awali field is hole collapsing in the surface section due to the presence of floating bloulders and cavities in areas of the field; resulting in wells being abandoned as conventional drilling was not enough to solve this issue. In 2019, Schlumberger and Tatweer Petroleum combined forces to improve production of Ostracod/Magwa shallow reservoirs by drilling wells in new areas of the field which included drilling in locations with offset wells that were abandoned due to hole collapse issues in the first 500’ interval. Drilling campaign started in june 2019 and drilled succesfully two wells, but two others were abandonned due to hole collapse issues. These abandonned wells were in very promising production areas as per the reservoir model and due to the shallowenest of the reservoir, it was not possible to move the surface location. Therefore, the issues in the surface section needed to be solved in order to maximize profits in the country. Following a rigerous study for determining which is the optimal solution for drilling the surface section in this area of the field, Casing While Drilling (CwD) technology was selected and implemented in August 2019 in well A-1530D, next to the previous abandoned wells. CwD operation was performed with excellent results by drilling from 101ft to 520ft with no issues. CwD successfully isolated the higly problematic zones in the surface section and more importantly, allowed to reach areas of the reservoir that had high potential for production.

Subsea Re-Abandonment Strategies for High-Risk Wells to Minimize Leakage Risk in a Depleted Field for CO2 Storage

CO2 storage in a depleted field comes with the risk that is associated with wells integrity which is often defined as the ability to contain fluids with minimum to nil leakage throughout the project lifecycle. The targeted CO2 storage reservoir in offshore Malaysia has existing abandoned exploration/appraisal, and development wells. With a view of developing such CO2 storage sites, it is vital to maintain the integrity of the abandoned wells. High-risk characterized wells need to be analyzed and remedial action plan to be defined by understanding the complexity involved in restoring the integrity. This will safeguard CO2 containment for decades. Abandoned exploration/appraisal wells in the identified field are >40 years old and were not designed to withstand CO2 corrosion environment. Downhole temperature and pressure conditions may have further degraded the wellbore material strength elevating corrosion susceptibility. The reservoir simulation predicts that the CO2 plume will reach to these abandoned wells during the initial phase of total injection period. Single well was selected to assess the loss of containment through the composite structure along the wellbore and to determine the complexity in resorting the well integrity. CO2 leakage rates through all possible pathways were estimated based on numerical models and the well is characterized for its risk. For unacceptable leakage risk, the abandoned well needs to be re-entered to restore the performance of barriers. Minimum plug setting depth (MPSD) and caprock restoration considers original reservoir pressure(3450psia) anticipating the pressure buildup upon CO2 injection and is derived based on fracture gradient and maximum horizontal stress. This paper elaborates unique challenges associated with locating abandoned wells that are submerged below seabed. Top and side re-entry strategies are discussed to overcome challenges. Based on past abandonment scheme, leakage rate modeling calculates estimated leakage rate of ~460SCFD at higher differential pressure of around 3036psia at shallowest barrier and ~15SCFD for differential pressure of 1518psia at deepest barrier. Sensitivity analysis has been carried out for critical barrier parameters (cement permeability, cracks, fractures) to the containment ability and improving understanding of quality of barriers, uncertainties, and complexities for CO2 leakage risk. The paper proposes two(2) minimum plug setting depths (3550ft & 3750ft) derived based on fracture gradient and maximum horizontal stress. Perforate-wash-cement (PWC) and section milling were compared for operational efficiencies to achieve caprock restoration. for MPSD out strategic options to restore well integrity by remediating casing/cement barriers at by performing best fit abandonment technique to contain CO2 in the reservoir. Well integrity risk is assessed for existing plugged and abandoned (P&A) wells in a carbon storage site. Optimized remedial actions are proposed. Quantification of all the uncertainties are resolved that may affect long-term security of CO2 storage site.

Reduction of Energy Consumption for Water Wells Rehabilitation. Technology Optimization

Groundwater wells are widely used in the energy sector, including for drinking water supplies and as water source wells in the oil and gas industry to increase production of natural gas and petroleum. Water well clogging, which can happen to any well for various reasons, is a serious problem that can lead to increased power costs due to a higher head to the pump, a reduction in the flow rate and various drawdown issues. If rehabilitation procedures do not take place in time, this can result in permanent loss of the well, and a new well must be drilled, which is not a sustainable approach. Rehabilitation methods for water wells usually include mechanical and chemical treatments, and even though these methods are well established and have been used for many years we can still observe many abandoned wells which could be rehabilitated. In this study, sets of cavitation generators are developed and used in combination with common conic hydrodynamic nozzles. This combination reduces the pressure in the system and makes the cleaning setup much lighter and more mobile. The designed nozzles were successfully used in hydrodynamic cleaning of four water wells.

The problem of fluid filtration through cement stone on gas fields with low reservoir permeability

Partial destruction of cement stone or an increase in its permeability during the development of oil and gas fields is a frequent occurrence. There are a huge number of natural and man-made factors that lead to an increase in the gas permeability of the cement ring. This article attempts to investigate the permeability of cement stone in active and abandoned wells. It presents an overview of experimental works devoted to determining the real permeability of cement stone on samples and according to the results of studying the state of wells in various conditions.

The Assumption of Zero Leakage from Permanently Abandoned Wells on the Norwegian Continental Shelf

Quality data is essential for calculations of expected leakage in wells post Permanent Plug and Abandonment (PP&A). Such data may come from surveys studying hydrocarbon leakage to the marine environment. However, recent literature suggests that current regulatory practices for environmental surveys are suboptimal, giving reason to question the assumption that wells have experienced zero leakage from the deep reservoir post PP&A on the Norwegian Continental Shelf (NCS). We investigate whether such an assumption is credible. The credibility of the assumption of zero leakages is investigated through a review of literature addressing the integrity of wells post PP&A on the NCS, with particular emphasis on a 2021 report from the Norwegian Environmental Agency (NEA). Based on the review, the strength of knowledge supporting the assumption that no wells on the NCS have experienced leakages from their deep reservoirs is discussed. The implications of the uncertainty associated with the assumption of zero leakage on the NCS, the rationale for collecting more relevant data, and how these data may be obtained is also discussed in brief. The NEA report details the current regulatory practice for environmental surveys on the NCS. This regulatory practice, as it is described in the NEA report, give limited support to a zero leakage assumption. Norwegian regulations require two environmental surveys post Cessation of Production (CoP). These surveys may however occur in the period between CoP and PP&A, and the closest test stations are generally located 250 meters from the wells. Environmental surveys carried out that far from the well, and possibly prior to PP&A, influence data quality. We argue that the environmental survey data claiming zero leakage, lack sufficient evidence. Thus, based on the reviewed literature outlining the current environmental survey practice, although PP&A well design on the NCS should build on sound principles, we are not able to conclude on the assumption of zero leakage. The interest in risk-based PP&A approaches is increasing globally, and risk-based approaches rely on credible leakage calculations. The failure rates used in these leakage calculations should be based on quality data. The NEA report and other literature indicate that the quality of post PP&A leakage data on the NCS is questionable, and in some cases the data are non-existent. The paper includes suggestions on how to improve the regulatory practice related to environmental surveys.

Environmental Challenges Associated with the Maintenance of State Wells in the Licensed Claim

Legal and environmental issues associated with the maintenance of state exploration wells in the licensed claim have been discussed. The causality of the abroad well decommissioning have been stated. General procedure of well decommissioning as part of a major overhaul have been stated. The structure has been analyzed and the research of the exploration wells technical condition of the Kharasaveyskoye deposit have been performed by the airvisual, geodetic and gas analytical study. The conclusion is that the condition of decommissioned and plugged and abandoned wells is satisfactory. The necessity of wells' sites reclamation has been substantiated to stabilize the land forms transformation by managing biofilters and bio-covers on the methanogenic territories.

Hide and Seek: The Orphan Well Problem in America

It’s a problem as old as the industry itself. The initial oil rush in the late 1800s spread like wildfire through Pennsylvania, and by 1891 the state’s annual crude output had hit 31 million barrels, or 58% of the nation’s total oil production for that year. However, by the turn of the century the bloom was off the rose. Pennsylvania’s once-robust oil allure had been eclipsed by finds in Texas, California, and Oklahoma, each spawning its own regional oil booms. So why the history lesson? Because it’s important to understand the potential volume and impact of orphan wells in the US. In the infancy of the industry, plugging-and-abandonment (P&A) techniques were crude at best, if anyone even went to the trouble. Worse still was the overall record keeping at the time. With oil booms around the country setting off races to harness as much black gold as possible, wells were being drilled at breakneck pace. Once these earliest wells were tapped of their commercial usefulness, operators moved on to the next. There was little-to-no over-sight. No regulations. No standards. The result? Thousands, if not more, of scattered, undocumented wells. “Back in the day, you have people drilling wells, and nobody’s keeping track of where the wells are drilled and who owns the wells,” said Daniel Raimi, fellow with Resource for the Future, an independent institution that conducts environmental, energy, and natural resource research. “The government’s not keeping track and has little to no regulation in place to ensure that operators safely decommission their assets at the end of their lives. As a result, you have wells that maybe produce for a couple of years, and then the owners walk away. Multiply that by a couple of hundred thousand and now you’ve got a problem.” Today, there is plenty of oversight and regulation for the industry to leave abandoned wells in much better shape than those earliest probes. However, orphan wells are still a problem. To paint the clearest picture, it would be prudent to define what an orphan well is. This is where we run into our first problem. Definitions can vary wildly from state to state and organization to organization. Some lump all abandoned, unplugged wells into their counts as orphan wells. Others count all idle wells. However, for the sake of clarity we will define orphan wells as those nonproducing, idle wells whose ownership is unknown. By that definition it is safe to say that many of the nation’s earliest wells fit that criteria. In more modern times, orphans result from idle wells whose owner goes belly-up prior to any P&A work. In most of these cases, bonds are employed to help offset the cost of plugging these wells. However, while they vary state to state, most bonding minimums do not cover the full cost of abandonment and remediation, if needed. According to the US Environmental Protection Agency, there are about 2 million unplugged, abandoned oil and gas wells scattered across the US. Other experts place the number higher; some believe it is lower. Some researchers believe as many as half of those could be orphan wells. A survey by the Interstate Oil and Gas Compact Commission in 2018 put the range of orphaned and idle wells at around 560,000 to 1.1 million. Again, abandoned doesn’t always mean orphaned. One fact that can be extrapolated from the data gathered to date is that no one knows for sure just how many orphaned wells are out there. But that is changing.