SYNOPSIS The use of stemming plugs in surface blasting is gaining popularity because of the environmental, technical, and economic advantages. Although previous studies have established the operational effectiveness of different types of stemming plugs, evaluations of the economic and ergonomic impacts are lacking, thereby hindering their application in many mining operations. Consequently, a significant proportion of mining operations end up performing less efficient blasts. We evaluated the effectiveness of three types of stemming plugs by conducting multiple full-scale production blasts. The results show that stemming plugs reduce the need for secondary blasting and increase blast performance. An economic analysis showed that the incorporation of stemming plugs can reduce blasting costs significantly. Keywords: stemming plugs, economic analysis, blast performance, surface mining, confinement.
Saudi Arabia has at today a reported fourth largest reserve of Natural gas in the world and as the fastest growing energy consume in the Middle East it is also consuming the totality of the national gas production, having no net import or exports of Natural Gas. The Natural Gas production and consumption was increased by 62% in the last 10 years and the demand in the country is expected to double the actual capability by 2030. This is the proposed target, and it is expected to be achieved under significant investment of foreign companies that are planning and executing projects related with non-associated gas fields in different areas of Saudi Arabia. Several oil companies are focused in explore, and produce in case of success exploration campaign, from high pressure, high temperature and deep gas reservoirs. The grade of reservoir properties anisotropy including the high uncertainty of pore and fracture pressures in the hostile environment that a conventional drilling practice will face in the deep exploratory wells is not resulting at the end as an efficient and viable way to reach the planned production target. The correct application of a new technology as Managed Pressure Drilling (MPD) has demonstrated the impact in the successful result obtained specifically in Saudi Arabia. This paper is summarizing the planning process behind an MPD project as well as the description of the obtained results in a case history. In the exploratory well project case developed in this paper, the main driver for MPD was to reduce the Non Productive Time usually experienced in other exploratory off-set wells drilled in the same basin by ascertaining in real time the reservoir pressure limits (pore and fracture) controlling mud losses and influx events associated with the new formation drilled. The right determination of the pressure balance between fluid losses and influxes was achieved and the operational window was successfully managed during all the stages of the MPD operation. Traditionally, the high solids content of the drilling fluid used in conventional drilling practices in this area, which main objective is to obtain an extreme overbalanced condition that could overlap the high level of reservoir uncertainties and anisotropy, is also damaging the reservoir itself, impacting the final production and productive life of the well. The content of solids was reduced to the minimum during this MPD operation, managing the annular pressure just by manipulating the MPD equipment adjusting in real time the back pressure exerted from surface. MPD reduced at the minimum the drilling non productive time associated with common hazards usually observed during conventional drilling practices in the same area and also finalized the exploratory well drilled in this deep gas reservoir without report any incident. In addition it has improved the reservoir production compared to the wells that were drilled conventionally.
In this paper, attempts have been made to describe the experiences of 1.5 months of Managed Pressure Drilling (MPD) operations conducted in hard rock Formation in Rub Al-Khali, Eastern province of Saudi Arabia.The implementation of this technology arose from the lessons learnt from previously drilled 2 exploratory wells that penetrated the tight gas sandstone Formations of Sarah and Qasim at a depth exceeding 17,000 ft, where the temperature and stress are extremely high at 350 o F and 1.0 psi/ft respectively. As a result of these conditions, it is necessary in all cases to perform hydraulic fracturing to define fluid characteristics and evaluate production potential.The extreme low porosity range of 2-10 % coupled with low permeability range of 0.01 -0.26 mD and high fracture gradient interval of 0.9 -1.0 psi/ft are the main challenges on these wells. Moreover, other challenges faced include drilling with high overbalance mud weight across the reservoir and high abbresivity of the formation rocks resulting in difficulty identifying potential gas bearing sands and slow drilling rate respectively.As a part of the referenced exploratory activity in the 3 rd quarter of 2008, LUKSAR was challenged to drill across the target reservoir with minimum formation damaged, balance mud weight and swift reaction in identifying suitable coring interval. Hence, in response to these challenges, an extensive study and well design/engineering were carried out in order to accommodate the utilization of Managed Pressure Drilling (MPD) across Sarah-Qasim sandstone Formation on wells LUK-08 and LUK-09. This paper summarizes the well operation and in particular lessons learned during the first field application of Managed Pressure Drilling (MPD) in LUKSAR Exploration Campaign that resulted in significant improvement in well deliverability compared to previously drilled wells in Sarah-Qasim structure.
The frontier exploration drilling campaign in the Kingdom of Saudi Arabia for LUKOIL Saudi Arabia Energy Ltd started in January 2006. LUKSAR, a joint venture between Lukoil & Saudi Aramco, took pragmatic approach to project management. A careful analysis of campaign challenges with proper planning to meet the drilling campaign targets. One major challenge was to stick to well program to ensure well targets are met and exploration objectives achieved. The reduction of wellbore diameter due to hole problems during well construction has always posed a great challenge to well completion. Having said that, there are few technologies at present that provide the capability to execute well intervention/work-over in slim hole wells and where there are available, they usually cost a fortune. The restriction created in reduced hole sizes typically results in a complicated drill stem testing program (DST), formation fracture pressure limitation, decrease in production rate due to restriction in tubing selection and high intervention cost. On Luksar Expl well #4, the above mention challenge was a reality. While drilling, encountered severe loss circulation in Shu'aiba carbonate formation compounded with sloughing shale problems in the shallower Wasia formation. As a result, it became difficult to drill further and set planned casing at bottom. Utilizing expandable tubular across loss circulation zone enabled Luksar to restore the original well casing design. Introduction Losses of whole mud to subsurface formations is called lost circulation or lost returns. Historically it is one of the primary contributors to high mud cost. Other hole problems such as wellbore instability, stuck pipe and even blowouts have been the result of lost circulation. Besides the obvious benefits of maintaining circulation, preventing or curing mud losses is important to other drilling objectives such as obtaining good quality formation evaluation and achieving an effective cement bond on casing. The Shu'aiba Formation consists mainly of different types of carbonates (limestone and dolomite) depending on the well location. The vast extent of Shu'aiba is porous with fast ROP. Shu'aiaba is an oil and gas reservoir in some of the off-shore wells. In 90% of areas it is a loss of circulation zone like in all Gulf States and especially in the Kingdom of Saudi Arabia. Estimated pore pressure range 8.4–8.5 lbm/gal with recommended mud weight 8.7–9.9 lbm/gal. The majority of non-productive times associated with drilling through this reservoir include:Lost CirculationUnexpected high-pressure areasHole integrity and wellbore stabilityFormation to formation cross flow Drilling through such formations provides many opportunities to experience one or more of these risks either while RIH, drilling or POOH. These risks potential means that at least one additional string may be needed to isolate the troublesome zone and to drill ahead to the planned casing point.
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