Oil and gas exploration and production (E&P) activities consist of many elements including numerous investors, complicated techniques, different work categories and procedures, grade separation, and continuous operations. These elements may lead to many risks, including spills, blowouts, pollution, discharged effluents by daily drilling operations, well treatment chemicals, etc. If effective strategic measures to minimize these risks are not implemented, severe accidents may occur with a negative impact on the workers’ safety and health as well as harming the environment, according to a paper entitled ‘Environmental Risk Management and Mitigation Strategies for Offshore Gas Well Drilling Projects,’ by Moussa Elbisy and Ehab Mlybari in the Journal of Civil, Construction, and Environmental Engineering.
For this reason, risk management is crucial to ensure that adequate measures are taken to protect workers via the implementation of Health, Safety, and Environment (HSE) standards. “The implementation of HSE standards, in general, improves the working environment, operations efficiency, and results in [raising] employees and stakeholders’ satisfaction,” Taher Gado, HSE Manager at Apex, said.
For instance, with an eye on drilling operation, two major waste by-products are produced: water and drilling-related waste. Each well can generate thousands of barrels worth of drilling waste; however, the volume of that waste differs according to the depth and diameter of the wellbore. Therefore, the proper management of drilling waste is necessary to eliminate its dangers. Furthermore, many governments and international conventions began issuing regulations and standards for more enhanced drilling waste management, according to a paper entitled ‘Drilling Fluid Waste Management in Drilling for Oil and Gas Wells,’ that was published in the Italian Association of Chemical Engineering (AIDIC).
Drilling Fluid Impact on Health, Environment
Focusing on drilling fluids or mud, such products are mixtures of fine-grained solids, inorganic salts, and organic compounds. These mixtures are dissolved or dispersed in a ‘continuous phase’ (i.e. the base fluid) which may be water or an organic liquid, according to a paper by International Association of Oil and Gas Association (IOGP), entitled ‘Drilling Waste Management Technology Review.’
Consequently, there are four main types of drilling fluids: Water Based Drilling Fluid (WBDF), Oil Based Drilling Fluid (OBDF), Synthetic Based Drilling Fluid (SBDF), and Pneumatic Drilling Fluid. These four types differ mainly in their composition and application. It is worth noting that, in order to have a proper selection for drilling fluid, one must consider multiple factors such as safety, economic considerations, technical performance, and environmental impact.
Exposure to drilling fluid can cause adverse health effects. The extent of being influenced by such fluids highly depends on “the physio-chemical properties of the drilling fluid as well as the inherent properties of drilling fluid additives, and are dependent on the route of exposure such as dermal, inhalation, oral and others,” Hatem Alkilany, QHSSE Director and DPA at Maritime and Oil Services Company (Maridive), noted. Moreover, exposure to drilling fluids, in itself, is a function of duration and frequency, along with other factors such as drilling fluid temperature flow rate, well depth, well section and kinematic viscosity of drilling fluid which can influence the exposure level in the workplace. Building on that, there are different scenarios to drilling fluid exposure, such as sampling, maintenance, and inspection processes.
When it comes to negative impacts on health, the most common health effects from drilling fluid to a human’s health could include skin irritation and contact dermatitis. Nevertheless, other health-related impacts such as headache, nausea, eye irritation, coughing, and inhaling aerosols and vapors, are not uncommon
Looking at the drilling fluid impact on the environment, detrimental harm could be caused if not cautious. The degree of damage on the environment vary depending on the type, dosage, and exposure duration to chemicals. Moreover, the physical and chemical properties of drilling fluid wastes determine the wastes’ hazardous characteristics as well as environmental impact.
Furthermore, the direct discharge of drilling fluid may affect the ecosystem of the environment via direct toxic effects of drilling waste, smothering organisms, and anoxic conditions caused by microbial degradation of the organic components in waste.
It is worth mentioning that one of the most significant threats of drilling fluid waste on the environment is heavy metal. Heavy metal in drilling fluid discharge could potentially lead to bioaccumulation in aquatic organisms. “[Water-base mud] WBM drilling cuttings are the fragments of rock resulting from drillings and carried to the surface with the drilling fluids,” Mahmoud Noureldeen, General manager of Green Plus Environmental Solutions, said, adding that “discharges of WBM drill cuttings can result in the covering of seafloor that provides habitat for some benthic organisms.”
Additionally, toxicity is used to measure the impact of drilling fluid on the environment. Out of the four types of drilling fluid, OBDF is considered the most toxic type which has the most severe effect on the environment, and WBDF is the least toxic one.
A study was conducted in a paper entitled ‘Environmental Risk Management and Mitigation Strategies for Offshore Gas Well Drilling Projects’ in an area located in the semi-circular basin of Abu-Qir Bay with a depth of approximately 28 meters (m) and was around 23.6 kilometers (km) from the shore. The offshore development well was drilled to 3.325 m (around 11,000 feet (ft)) True Vertical Depth Subsea (TVDSS). The water depth at the proposed well is +/- 28.346 m (approximately +/- 93 ft) and the drilling operations were supposed to be done within 70 days.
During the drilling operation, drilling mud was used to lubricate the drilling string, cool the rotary drill bit, and carry the rock cuttings from the well bore to the surface. Then, the drilling mud would be transferred to isolated boxes from the rig to the contractor’s base to be environmentally safe, hinder the entrance of undesirable formation fluids into the well bore, and control excessive pressure in the well bore to prevent blowouts.
The Environmental Impact
It is necessary to determine the significance of the drilling process’s impacts on the environment to see the possibility of rehabilitating the environment after any damage during drilling operations and to see whether these impacts are acceptable, need mitigation, or unacceptable at all.
Air quality is one of the environmental sides that needs to be considered. As a result of the project activities, many emissions were produced with an effect on the offshore atmosphere. These greenhouse gas emissions included carbon dioxide (CO2), methane (CH4), nitrogen oxides (NOX), Sulfur dioxide (SO2), carbon monoxide (CO), and volatile organic compounds (VOCs). These emissions resulted from many sources including marine vessels, machinery and equipment.
Another impact to consider is water quality. Drilling activities were assessed to have an impact on the environment of seawater as well as its biological life. The features that affect the seawater environment include aqueous discharges to the sea of drilling cuttings, drilling fluids, in addition to water-based mud drill stem tests. The discharged drilling fluid and cuttings contain concentration of metals which have a limited bioavailability to marine organisms because of their composition. Furthermore, oil spills may occur, and any spills without treatment will have a short-term and long-term effect on the existing marine ecosystems.
Mitigation measures are needed in order to minimize the negative impacts of drilling fluid. For instance, many measures can be taken to enhance air quality. These measures include employing dust suppression measures and prohibiting waste burning on the site. In addition, all machines must be maintained under the manufacturer’s standards to ensure operational efficiency.
When it comes to water quality, the contaminated drainage must be treated with an oil or water separator. Also, waste from sewage water must be treated as well to reduce the concentration of organic material prior to discharge. Besides, all solid wastes must be transported to shore for water disposal. In addition, prompt containment using floating booms and other means of recovery will be performed as a quick response to oil spills.
In order to mitigate the negative impacts of drilling fluid, it is better to use Barite (or Barium Sulfate) with a very low concentration of heavy metals to ensure that the mud is environmentally safe, as well as using a closed circulation system for drilling mud.
All risks related to the installation of the rig and its operational support facilities should be considered to eliminate the hazardous impacts on the environment and the working staff. It is worth noting that the hazards from spills are covered by Abu Qir’s formulated oil spill contingency plan. Therefore, the main strategy adopted to minimize the occurrence of adverse impacts should include a minimal use of hazardous materials in drilling fluids, near zero discharge of effluent from drilling operation, as well as implementing safety measures and monitoring activities to ensure that contamination does not occur.
There are various ways to manage drilling fluid waste and protect the environment from its dangers. These ways include direct discharge to the sea, application to land, re-injection, on-site dewatering, and using an offsite treatment facility.
The selection of the proper waste management method must consider economic, environmental and operational aspects of the waste management. Choosing a proper waste treatment is a crucial step to implement before any direct discharge to sea takes place, according to Alkilany, the “sea discharge may prove to be the most economical option, considering immediate cost of disposal, but the decision must also consider environmental impact, local regulations and operational aspects such as additional equipment for treatment.”
Speaking about drilling fluid cuttings, “[they] should be collected in specially designed cuttings bins and sent to the treatment site for special treatment,” Noureldeen said, adding that “specially designed cuttings bins (Certified to BS 7072 standards) are filled using cuttings transfer pump in an area having a purpose-built platform equipped with appropriate spill containment. All the bins are sealed after filling on the rig. The capacity of each bin is 6.0 metric tons.”
Moreover, any drilling cuttings received and did not comply with the conditions of the site license, “are either rejected and returned to the producer or they may be offloaded in the designated quarantine area while investigations are completed,” Noureldeen pointed out, clarifying that “drilling waste is not received at the site unless there is appropriate equipment and plant to ensure its safe handling and containment.”
Hence, accepted drilling wastes are stored in on-site tanks, and the bins are then transferred to the bin washing area for cleaning before reuse, Noureldeen explained, adding that “the bin washing area is designed in way to ensure that all wash water drains down towards the collection sump, thus preventing contamination of surrounding soil and groundwater.”
Considering the vitality of protecting the workers’ health from the negative impact, many measures can be implemented. The first method is through eliminating the hazardous materials in drilling fluid to reduce workers’ exposure to risk during drilling operation. Also, using low toxicity drilling fluid or WBDF to reduce the carcinogenic hazards can have a positive impact. In addition, the design of the workplace should include engineering controls, such as ventilation system and enclosed drilling fluid circulation system, to minimize workers’ exposure to hazardous substances.
Moreover, monitoring the level of exposure by conducting the air monitoring and skin monitoring can manage the human’s exposure impacts. Furthermore, one of the most effective ways to have a significant control is personal protective equipment, like mask, rubber glove, splash goggles, rubber boots and coveralls. Such equipment acts as a protective barrier to the workforce.
It is worth noting that international oil companies (IOCs) have a vital contribution in eliminating this issue, “IOCs, represented by the IOGP, developed standards for the management of drilling waste including drilling fluids. It is a moral and ethical responsibility on the shoulders of IOCs to implement these standards as well as the local and national standards – whichever is more stringent – consistently in their operations worldwide regardless of the activeness and ability of the law enforcers to inspect the implementation,” Gado commented, adding that “saying something and doing something else will give the workers the impression that their employers do not care about them and will reflect on them by ignoring the implementation of any other HSE standard.”
In conclusion, drilling fluid waste management represents a cornerstone to ensure that the HSE standards are implemented appropriately. Thus, such standards will help protect the environment and the workers’ health from different hazards.