The injection of drilling generated waste into a selected subsurface formation has evolved into the most preferred waste disposal technology in terms of environmental compatibility and cost effectiveness, especially for remote and environmentally sensitive areas. The main principle of waste injection (WI) is the initiation of hydraulic fracture and the placement of solids within the created fractures through the high-pressure pumping of slurry batches. The fracture propagation is governed mainly by in-situ stresses. As injection progresses solids accumulation in the fracture leads to an increase of in-situ stresses within the injection zone causing a build-up of injection pressure. As allowable injection pressure is often limited by equipment, the undesirable or rapid injection pressure build-up could jeopardize the operational life of an injection well and limit its waste disposal capacity. This paper introduces a new approach to a regular seawater injection by investigating the relationship between pressure behavior and seawater injection. Displacement of slurry from the tubing by seawater over flush is carried out routinely in WI operations worldwide. However, never before it was considered as a pressure maintenance tool. The authors describe the impact of continuous seawater injection on injection pressure through the lifetime of three waste injectors. The injection pressure behavior before, during and after continuous seawater injection was reviewed using downhole measured data. It was noticed that regular seawater over-displacements during the continuous time periods between slurry injections reduced injection pressure considerably. Consequently, a thorough evaluation was initiated to investigate the impact of extended seawater injection on in-situ stresses and its potential advantage in maintaining the injection pressure within lower limits. Considering the novelty and value of study for expanding worldwide WI operations, this paper presents the new approach to seawater injection as an injection pressure and disposal capacity maintenance tool. Introduction In the early 1990s, WI emerged as a new technology that could provide an environmentally safe and economically sound solution to the disposal of drill cuttings and associated wastes in environmentally sensitive and remote operations. It was identified as one of the few technologies able to provide a complete drilling waste disposal solution that eliminates the need to accumulate, store and haul cuttings to shore for treatment. First pioneered with small volume annulus injections in the Gulf of Mexico in the mid-1980's the technology has since gained broad use in the North Sea, Alaska and other areas where the environmental conditions, tight regulations and logistics made this a viable drilling waste management option.1, 2 WI has been implemented successfully in the Caspian Sea since 2006, despite a complex subsurface environment and tectonics that presented significant technical challenges for vigilant monitoring and pressure interpretation as injection progresses.3 Pressure follow-up was recognized as critical to ensuring the safe and long-term containment of the waste to be injected.

As the worldwide consciousness concerning environmental protection evolves along with the technology, the need for new methodologies to dispose of oilfield wastes in a safe manner grows under tight governmental regulations and careful management of risks, liabilities and costs. This is particularly true for remote areas such as deep water and environmentally sensitive locations where there is a strong emphasis on protecting the natural resources of the drilling area. Accordingly, many regulatory agencies demand zero-discharge policies and require all generated wastes to be disposed in a responsible manner. Such a process involves the adequate management of by-products generated during drilling operations including cuttings, excess drilling fluid, contaminated rainwater, produced water, scale, produced sand, and even production and cleanup waste. Old practices involve temporary box storage and hauling of the waste products to a final disposal site. Often, these practices create not only liabilities for the operating company but also environmental risks such as accidental spills, gas emissions and eventually, high operating costs.Waste Injection (WI) into sub-surface formations has proven to be the most effective technology for final disposal of wastes from oil and gas drilling and production that provides a secure operation achieving zero discharge. WI achieves this by storing the injected material several meters below surface in hydraulically created fractures, avoiding surface environmental risks and future liabilities for operating companies.This paper presents the methodology based on risk analysis, supported by successful worldwide case histories, to prepare an operational and cost-efficient operation that continuously analyzes information and provides fit-for-purpose recommendations to achieve a seamless injection process. The Assurance Waste Injection process permits the detection and identification of potential risks giving mitigation options to prolong the life of the injector.

Waste generated during exploration, development, and production of oil and gas fields are required to be disposed in a responsible and environmentally friendly manner. Over the years, environmental regulations governing the disposal of such waste have tightened and each day regulatory agencies are demanding more stringent policies, especially for remote and environmentally sensitive areas. Waste Injection (WI) has been proven over the past decade to be the safest and most efficient technology for final disposal of waste materials such as produced water, drill cuttings, spent drilling and completion fluids, scale waste, NORM, produced sand, production and well cleanup waste. This cost-effective technology complies with the strict environmental guidelines, such as the ones governing zero-discharge environments. More regulatory agencies are gradually recognizing WI as a robust solution to safe and assured final disposal of waste generated in upstream and downstream sectors of the oil industry.WI has evolved from a simple pumping operation, with lack of sub-surface understanding, to an assured process that has integrated the knowledge from all areas of the operation: engineering design, equipment and operational parameters, monitoring, and quality control-quality assurance. This continuous assessment guarantees a cyclic process that identifies potential risks at early stages, and allows proper management and mitigation to prolong the life and integrity of the operation. This paper presents the unique and technically challenging injection monitoring and pressure interpretation experience attained in different WI projects worldwide, where the in-depth interpretation of fracture behavior helped as a risk-prevention tool with mitigation options applied to operational parameter well specifics.The continuous monitoring of injection data and parameters assists in developing a well history and a prediction mechanism for well storage capacity, extending the life of the injector and maximizing efficiency for the development of the field.

While engineered, operated and monitored properly, Cuttings Re-Injection or Waste Injection (WI) -injection of drilling generated waste into selected subsurface formations through initiation of disposal fractures -has proven to be an environmentally friendly and cost-effective waste management technology allowing compliance with "zero discharge" requirements. Areas where it is becoming the technology of choice are continuously expanding and the FSU (Former Soviet Union) is not an exception. The first WI project in this region started in Russia (offshore Sakhalin) in 2000 and then was followed by projects in Azerbaijan (ACG) in 2006 and mainland Russia (Western Siberia) in 2008 1,2,3 . To date, more than 4.5 MM barrels of waste have been safely injected in the region with extremely low NPT -0.01%. Karachaganak is a giant gas-condensate field in Kazakhstan operated by KPO. Re-injection of drilling generated waste into a selected subsurface formation has been under investigation as a potential waste management option for the field for a few years. Lithostratigraphy and geological characteristics of sub-surface formations were investigated to identify availability of suitable intervals for cuttings injection. Further, a feasibility study identified thick interbedded sandstone/claystones of the Triassic and Upper Permian, as suitable for WI purposes. Hydraulic fracture simulations showed containment of disposal fractures within the target injection intervals and indicated sufficient disposal capacity of selected formations. Once the potential disposal formations were identified, the basic surface equipment and facilities capable of safely handling expected drilling waste was designed. Additionally, as there was no actual precedence of WI technology implementation in Kazakhstan, local regulations were briefly reviewed. Summarizing, the given paper outlines results of feasibility investigation and required surface facility and equipment parameters for WI technology implementation in the Karachaganak field.

As the world faces new challenges to protect the environment from all human-generated wastes, self-imposed industry policies as well as governmental regulations support new green policies towards implementing best, not necessarily least costly, practices to prevent any environmental damage due to spillage during operations. Waste Injection (WI) has been selected as the preferred methodology of final disposal of oilfield wastes, including cuttings, produced water, drilling fluids and tank bottoms, etc., by many operators and legislators because it achieves zero discharge in a safe and efficient manner at a lesser operating cost than comparable proven technologies. This may be particularly true for large-scale projects. Mexico, Argentina, Azerbaijan, USA, UK, Norway, Russia and other countries have strategically implemented WI operations in field developments because they comply with local laws and they avoid future liabilities as wastes are permanently isolated and stored below surface.The development and implementation of such technology in large-scale projects is carefully designed using a risk-based analysis that is comprised of fracturing studies of the area of injection, technologies integration, logistics, equipment specification and process monitoring, all with the aim of performing a seamless and risk-free operation. The following paper addresses planning and implementation methodology for WI operations with real examples that demonstrate the value of proper preparation and integration of various technologies to attain maximum efficiency under QHSE standards.