Horizontal wells present an effective method to maximize production potential and reduce development costs of some oil and gas fields. The ability to predict induced fracture direction with reasonable accuracy can allow the operator to drill in the direction considered most profitable.1 Ideally the well would have extended reach in the proper direction through a stable, fractured formation, would not require stimulation, and would not be subject to the production problems usually encountered in the life of a field. Since horizontal wells are drilled in a variety of formations, operators are experiencing the normal well problems and are finding stimulation and control methods useful for production improvement. This paper will examine problems associated with cementing of horizontal sections and the recent technology advancements that may be applied to help assure a competent annular hydraulic seal. Conventional cemented completions have not been used extensively in horizontal wells since some operators lack confidence in the technology that is available. Problems have been perceived in managing cuttings transport, pipe centralization, effective mud displacement, cement free-water control, and effective placement of a cement seal around the casing. These problems do exist and corrective techniques are complicated by highly deviated wellbores, but technology advances have been made to address horizontal conditions. Proper cementing may continue to provide an economical hydraulic seal for zonal or wellbore segment isolation so necessary to effective stimulation and work-over operations. The use of advanced technology often requires extensive pre-planning and includes the necessity to properly communicate the benefits to field operations personnel to assure the proper implementation of new or different techniques or materials. Little good will come from the best ideas without proper follow-through during application.

Considerable debate in the Middle East has centred upon what was previously felt to be two separate methods of enhancing revenues and daily production; hydraulic fracturing and horizontal drilling. In an effort to maximize return on investment, these two issues have been successfully combined in other areas of the world. In order to establish the suitability of this technology in this area, two horizontal wells with over 3,050m (1 0,000ft) of lateral section were drilled into the Cretaceous Kharaib formation, overlying the North Field, Offshore Qatar. A massive stimulation program was performed in order to evaluate the most feasible stimulation method from both a technical and economical perspective for further field development considerations. Three propped hydraulic fracturing treatments were performed using 183,500kg (403,700lb) of 20/40 mesh sand, and seventeen acid matrix treatments placing over 3,217,250l (850,000gals) of HCL into the lateral sections of both wells. This paper describes the performance, operation and logistical support required to complete this offshore operation within a minimal time frame. The use of a mobile offshore jack-up platform, whereby a land based fracturing spread was placed onto the deck of a converted drilling rig is described. Introduction The common application of hydraulic fracturing as a process for enhanced recovery is gaining acceptance throughout the Middle East. Recent treatments in Kuwait, Egypt, Saudi Arabia and Qatar show this to be the case, whilst an ongoing hydraulic fracture campaign continues in Oman. Hydraulic fracturing of wells in the Arabian Peninsular has primarily been limited to the few sandstone reservoirs in existence. This has been the case, as much due to the relative ease of performing acid fracturing treatments on carbonates, as it is due to their prevalent short term success. Historically, the Aptian Chalks of this region had been successfully fractured by massive acid fracturing utilizing the viscous fingering technique. P. 481

This paper describes the planning, laboratory evaluation, and fluid system development for a fracturing treatment on a horizontal completion in the Sahmah Field, Sultanate of Oman. The Sahmah field consists of two reservoirs, the Lower and Upper Haushi, part of the Permian age. The Upper Haushi comprises a sandstone formation overlying a dolomite bed. The sandstone is deep, hot, and has low permeability with pockets of moderate permeabilities throughout. In the past, improvement in productivity has been successful with hydraulic fracturing treatments. A horizontal completion in the sandstone with a combination of multiple fracturing treatments placed in the horizontal wellbore was considered as a method for optimizing production in the Sahmah field. The isolation of the field created logistic and well servicing problems, so four separate hydraulic fracturing treatments, to be performed prior to flowback, were planned. The laboratory testing carried out for fluid selection and fracture modeling for the horizontal completion form the basis of this paper.

Guest editorial This article addresses a political issue in the US, but JPT’s global readership also needs to be concerned when people, however well-intentioned, confuse fact with fiction. In the US, most of us believed that the benefits of natural-gas development were well understood. After all, natural gas is relatively clean, efficient, and very plentiful—especially now that technology has made unconventional reserves commercially viable. However, a political stumbling block has appeared that could threaten the future of unconventional gas development and derail the transition to this plentiful and relatively clean alternative energy source. We in the industry need to understand this threat and use our scientific expertise to overcome it. The challenge is this: the debate surrounding the merits of natural-gas production has become significantly clouded by misinformation and false assertions. As fracturing involves pumping large amounts of material deep into the ground, many misinformed stakeholders are concerned that the fluids could infiltrate their drinking-water supply. As a result, some believe that the process of hydraulic fracturing is potentially dangerous, and they have called on their elected representatives to enact regulations to ban or limit its use. The Real Threat This threat to our industry is real and specific. Currently, the US Congress is considering legislation that would add a new layer of punitive hydraulic-fracturing federal regulation. At a minimum, this would expand and complicate the permitting process and require detailed disclosure of fracturing fluids. This legislation is called the Fracturing Responsibility and Awareness of Chemicals (FRAC) Act. I am concerned that Congress may threaten the forward progress of our industry and take away the jobs and the economic boost that the global economy needs right now. Let me be clear—I am not arguing against regulation, especially considered regulation that serves to protect our health or the environment. Instead, what I am questioning is the need for broad and sweeping federal governance that stifles innovation, progress, and economic development. We need to discourage legislators from adding federal requirements that would suppress technology development, reduce natural-gas production from unconventional sources, and, in particular, restrict development of shale gas, a resource in plentiful supply around the world. As informed participants in an industry that, perhaps more than any other, has contributed to the global economic advance of the last 100 years, we need to be active in explaining why this move is unnecessary and contrary to the public interest. State Regulation Sufficient In the US, state regulation of fracturing, and of the oil and gas industry in general, has a long and successful history. The 27 states that account for hydrocarbon production have permitting requirements that cover the process of locating, drilling, completing, stimulating, and operating wells. These state regulatory systems have evolved along with the oil and gas industry; some go back to the 19th century.

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