Horizontal well completions

The production rates for oil (Q0J), water (Qwj) and gas (Qa) from a vertical or horizontal well completed in layer j are given by the following equations... 

Figure 2. Sand accumulation in horizontal wells. Complete plugging is possible when sinusoidal amplitude wellbore diameter. There is also the potential for development of longitudinal annular flow. (Reproduced with permission from reference 118. Copyright 1993 Nowsco Well Service Ltd.)...

Drilling performed with an air mist and / or water-based or oil-based muds for deep horizontal well completions. 

Rodrigues, V. E, L. E. Neumann, D. Torres, C. Guimaraes, and R. Torres. Horizontal well completion and stimulation techniques—a review with emphasis on low-permeability carbonates. Paper SPE 108075, presented at the Society of Petroleum Engineers Latin American and Caribbean Petroleum Engineering Conference, Buenos Aires. 

There will be some uncertainty as to the well initials, since the exploration and appraisal wells may not have been completed optimally, and their locations may not be representative of the whole of the field. A range of well initials should therefore be used to generate a range of number of wells required. The individual well performance will depend upon the fluid flow near the wellbore, the type of well (vertical, deviated or horizontal), the completion type and any artificial lift techniques used. These factors will be considered in this section. 

Completions in horizontal wells are also tailored to the individual reservoir. Figure 9.16 shows some options tor completing horizontal wells. 

Sohd salt, ground and packaged in several particle size grades, can be used in saturated salt brines to increase the fluid density (28). However, sized salt is most often used as a water-soluble material for bridging or sealing porous formations. At one time the sized salt systems were used primarily for completion or workover operations, but use has increased as ddU-in fluids for horizontal wells (29). 

Slip, or relative velocity between phases, occurs for vertical flow as well as for horizontal. No completely satisfactory, flow regime-independent correlation for volume fraction or holdup exists for vertical flow. Two frequently used flow regime-independent methods are those by Hughmark and Pressburg AIChE J., 7, 677 [1961]) and Hughmark Chem. Eng. Prog., 58[4], 62 [April 1962]). Pressure drop in upflow may be calculated by the procedure described in Hu mark Ind. Eng. Chem. Fundam., 2, 315-321 [1963]). The mechanistic, flow regime-based methods are advisable for critical applications. 

Horizontal wells can be drilled with a larger well spacing than vertical wells and, like vertical wells, may be completed open or cased hole. Recent innovations such as multibranches and multilegs off of the main section increase the efficiency and productivity of horizontal wells (12, 13). However, new technology is still needed to overcome difficulties associated with the use of horizontal wells, such as effective clean-out... 

Solids production and control remain a high priority for the petroleum industry. In conventional oil and gas operations, control of produced solids is a primary focus. In recovery of heavy oil from unconsolidated reservoirs, production and handling of large quantities of produced solids present special challenges, both in the removal of solids from the wellbore and their subsequent disposal. The rapid expansion of horizontal well applications has led to some unique approaches to solids handling and is likely to lead to new technical advances as the horizontal drilling and completions technology continues to advance. 

The Woodford Shale play is located in south-central Oklahoma it ranges in depth from 6000 to 11,000 feet (Table 5.6). This formation is a Devonian-age shale bounded by limestone (Osage Limestone) above and undifferentiated strata below (Figure 5.6). Natural gas production in the Woodford Shale began in 2003 and 2004 with vertical well completions only (Cardott, 2004) however, horizontal drilling has been adopted in the Woodford Shale, as in... 

The staging of multiple fracture treatments along the length of the lateral leg of the horizontal well allows the fracturing process to be performed in a very controlled manner. By fracturing discrete intervals of the lateral wellbore, the operator is able to make changes to each portion of the completion zone to accommodate site-specific changes in the formation. These site-specific variations may include variations in shale thickness, presence or absence of natural fractures, proximity to another wellbore fracture system, and boreholes that are not centered in the formation. 

It is too early in shale gas drilling and production process history to determine the final well spacing that will most efficiently recover the gas resource in all basins however, current experience indicates that the use of horizontal well technology will significantly decrease the total environmental disturbance. As a case in point, consider that complete development of a 1-square mile section could require 16 vertical wells, each located on a separate well pad. Alternatively, six to eight horizontal wells (potentially more), drilled from only... 

In June 1992, Texaco announced the completion of a pioneering dual lateral horizontal well in a fractured formation in the Gulf of Mexico. A vertical well was drilled into the pay zone, at which point the drilling of two horizontal wells were initiated, heading in opposite directions. This example shows how the flow from such a completion is easily simulated. Fictitious input parameters are used for illustrative purposes. For brevity, the GEO files will not be shown. 

When simulating the waterflood, the line drive configuration with vertical wells provided the quickest oil recovery and the best sweep efficiency, since the complete pattern was swept even at the edges. For a polymer flood, the use of three parallel, horizontal wells with a central injector provided the optimum configuration since the fastest oil recovery was achieved in comparison to the other configurations, as shown in Figure 11. By the year 2020, polymer flood with the horizontal well configuration recovered... 

Surprisingly, the vertical well configuration still provided the best sweep efficiency for the polymer flood since the edges of the horizontal well patterns were not completely swept However, the polymer injection rate was severely limited when using vertical wells and the parallel horizontal weU configuration was the more attractive alternative when injecting polymer into the reservoir to produce heavy oil at economic rates. 

The reservoir immediately to the west of the 11 -14 pattern, in Section 15, had yet to be developed on waterflood. After successful completion of the initial polymer pilot. Phase 2 of the polymer pilot would incorporate horizontal wells Section 15 was the logical candidate for this. 

For successful acidizing of horizontal wells producing from carbonate formations, the keys are treatment placement and efficient use of acid fluids. It is necessary to utilize one or more methods of acid placement or diversion, to impart treatment coverage over as much of the target interval as possible. This is especially challenging in open-hole completions or those utilizing slotted or predrilled uncemented liners. Such completions preclude use of ball sealers and most solid-particulate diverters. 

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