Drilling Wells

The main cost factor ot coring is usually the rig time spent on the total operation and the follow up investigations in the laboratory. Core analysis is complex and may involve different laboratories. It may therefore take months before final results are available. As a result of the relatively high costs and a long lead time of core evaluations the technique is only used in selected intervals in a number of wells drilled. 

The PIF estimate is only a qualitative check on the potential benefit of a horizontal well. There is actually a diminishing return of production rate on the length of well drilled, due to increasing friction pressure drops with increasing well length, shown schematically in Figure 9.6. 

When considering exploration economics, the possibility of spending funds with no future returns must be taken into account. A typical world-wide success rate for rank exploration activity is one commercial discovery for every ten wells drilled. Hence a probabilistic estimation of the reserves resulting from exploration activity must take into account the main risks and uncertainties in the volume of hydrocarbons in place, the recoverable hydrocarbons, and importantly the risk of finding no hydrocarbons at all. 

Hydrocarbon-water contact movement in the reservoir may be determined from the open hole logs of new wells drilled after the beginning of production, or from a thermal decay time (TDT) log run in an existing cased production well. The TDT is able to differentiate between hydrocarbons and saline water by measuring the thermal decay time of neutrons pulsed into the formation from a source in the tool. By running the TDT tool in the same well at intervals of say one or two years (time lapse TDTs), the rate of movement of the hydrocarbon-water contact can be tracked. This is useful in determining the displacement in the reservoir, as well as the encroachment of an aquifer. 

New technology is applied to existing fields to enhance production. For example, horizontal development wells have been drilled in many mature fields to recover remaining oil, especially where the remaining oil is present in thin oil columns after the gas cap and/or aquifer have swept most of the oil. Lately, the advent of multi-lateral wells drilled with coiled tubing have provided a low cost option to produce remaining oil as well as low productivity reservoirs. 

Onshore processing facilities, and modules brought onshore, have to be cleaned of all hazardous compounds and scrapped. Cellars of single wells, drilling pads, access roads and buildings will have to be removed. If reservoir compaction affects the surface area above the abandoned field future land use may be prevented, in particular in coastal or low land environments. 

A key factor in obtaining binding support for aquaculture is development of a sound business plan. The plan needs to demonstrate that the prospective culturist has identified all costs associated with estabhshment of the faciUty and its day-to-day operation. One or more suitable sites should have been identified and the species to be cultured selected before the business plan is submitted. Cost estimates should be verifiable. Having actual bids for a specific task at a specific location eg, pond constmction, well drilling, building constmction, and vehicle costs helps strengthen the business plan. 

Oilfield Uses. Calcium chloride has two uses in the oilfield as a primary ingredient in completion fluids and as the brine phase in an invert emulsion oil mud. An excellent review of oil well drilling fluids is available (36) (see also Petroleum, drilling fluids). 

Economic Aspects. CMC is the most widely used cellulose ether. Excluding the former Soviet Union and Eastern Bloc countries, from which httie data are available, world consumption of cmde and purified grades totaled approximately 123,000 metric tons in 1987 (Table 2). Annual growth rate is nominal at 1—2%. The total volume in the United States declined in the 1980s from —32,000 metric tons in 1981 to —19,500 in 1987 because of decreased oil well drilling activity, an important outiet. 

There are a number of metallic compounds of chromium that ate used either as the compound itself or as metallurgical constituents in Cr-beating alloys. Trichromium dicarbide [12012-35-0] is important as a wear-resistant gauge material chromium botide(l 1) [12006-79-0] CrB, for oil well drilling ... 

Sulfates or sulfonates Alkali metal salts of sulfated alcohols, sulfonic acid salts alkyl-aryl sulfonates sodium laiiryl sulfate Nonaqiieoiis systems mixed aqueous and nonaqiieoiis systems oil-well drilling muds spent H3SO4 recovery deep-fat frying... 

The Satanta plant went online in September 1993, processing natural gas from some 1,000 wells drilled in the Hugoton fields of southern Kansas. A day s production yields 13,000 bbl of liquified natural gas (LNG), 5.1 million Nm (190 MMscf) of residue natural gas, and 21,600 Nm (800,000 scf) of helium. 

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