Infill drilling

Original Profile Additional Reserves Accelerated Reserves Reduction due to Previous Acceleration 

Original Reservoir Pressure Profile ( Po ) Average Abandonment Pressure 

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Keywords production decline, economic decline, infill drilling, bypassed oil, attic/cellar oil, production potential, coiled tubing, formation damage, cross-flow, side-track, enhanced oil recovery (EOR), steam injection, in-situ combustion, water alternating gas (WAG), debottlenecking, produced water treatment, well intervention, intermittent production, satellite development, host facility, extended reach development, extended reach drilling. 

Infill drilling is another possible way to extend production. For a variety of reasons, some oil may not be available to the original wells in the resei voir. Some wells may be spaced too far apart to capture the oil between them. Gas or water flooding may have bypassed some oil, or fractures or faults may block off certain parts of the reservoir from the rest so that they cannot be drained from existing wells. In these cases drilling new wells between existing ones call be an effective way to capture more of the resource. 

Secondary recovery, infill drilling, various pumping techniques, and workover actions may still leave oil, sometimes the majority of the oil, in the reservoir. There are further applications of technology to extract the oil that can be utilized if the economics justifies them. These more elaborate procedures are called enhanced oil recovery. They fall into three general categories thermal recoveiy, chemical processes, and miscible methods. All involve injections of some substance into the reservoir. Thermal recovery methods inject steam or hot water m order to improve the mobility of the oil. They work best for heavy nils. In one version the production crew maintains steam or hot water injection continuously in order to displace the oil toward the production wells. In another version, called steam soak or huff and puff, the crew injects steam for a time into a production well and then lets it soak while the heat from the steam transfers to the resei voir. After a period of a week or more, the crew reopens the well and produces the heated oil. This sequence can be repeated as long as it is effective. 

Enhanced oil recovery is oil recovery by injection of gases or chemicals and/or thermal energy into the reservoir. It is not restricted to a particular phase, as defined previously, in the producing life of the reservoir. Another term, improved oil recovery (lOR), is also used in the petroleum industry. The terms EOR and lOR have been used loosely and interchangeably at times. Some feel that the two terms are synonymous others feel that lOR covers just about anything, including infill drilling and reservoir characterization. 

The terms EOR and lOR should refer to reservoir processes. Any practices that are independent of the recovery process itself should not be grouped into either EOR or lOR. Such practices include reservoir characterization, reservoir simulation, use of hardware and equipment (pumps, down-hole separators, etc.), use of special well types (horizontal wells, multilaterals, smart wells, etc.), improved reservoir management, infill drilling, and so on. Oil here means hydrocarbon, including oil and natural gas. 

A field test was condncted in the well 1-14 pattern in the eastern block of the Gndao field (Wang et al., 2005). The test formation was Ng3-4, and the formation thickness was 13 m. The clay content was 11.8%. In this test, the air permeability was 250 to 3165 md, with an average 1782 md, and the porosity was 30 to 32%. The initial reservoir temperature was 71°C. Before the test, the temperature was 64°C. The oil viscosity at reservoir conditions was 50 to 150 mPa s, and the formation TDS was 3850 mg/L. In the test well pattern, there were 1 injector, Dl-14, and 11 producers around the injector. In April 2004, infill drilling and conformance control were conducted. The water cut decreased only 2%. By January 2005, the water cut reached 96%. 

The charge model has been used in formulating a strategy for infill drilling to develop additional reserves within the Judy Field. Petroleum-water contacts and fluid types are in line with pre-drilling predictions. 

Most oil occurs in the narrow channel deposits which are vertically stacked. Recovery of oil through displacement by water flooding and thermal injection will require Infill drilling. Therefore knowledge of the reservoir framework will be the key to the development of these shallow sands. 

Infill drilling is used to increase the production rate by drilling between producing wells in an established field. 

This book introduces classes of steady-state solutions that the interested reader can extend and generalize. They are particularly meaningful to reservoirs that produce under near-steady conditions at high rates, typical of many oil fields outside the United States. The solutions are useful in studies related to flow heterogeneities, hydraulic fractures, nonlinear gas flows, horizontal drilling, infill drilling, and formation evaluation. The analytical techniques used are described in detail, applied to nontrivial flow problems, and extensions are outlined in the Problems and Exercises sections at the end of each chapter. 

So far we have performed detailed studies for flow over isolated bodies, for example, curved fractures, shale arrays, and fractured boreholes. Here we will focus on steady and transient-compressible reservoir-scale flows produced by multilateral well systems. Because their topologies are not simple, we turn to computational methods. We will highlight problems that arise in reservoir simulator development, and importantly, we will describe a recently developed, three-dimensional algorithm that is very robust, numerically stable, exceptionally fast, and extremely accurate, and now available to the user community. Engineering implementation is an objective of the work oil companies want practical solutions that optimize operations, profits, and time value of money. The model provides tools that evaluate what if production scenarios, infill drilling strategies, and waterflood sweep efficiencies. In addition to being accurate, the solutions require minimal hardware, software, and costly human resources. 

The final frontier for polymer applications in the East Bodo Field will be the expansion of the teclmology into parts of the reservoir characterized by gas cap, bottomwater or both. Infill drilling proved uneconomic with primary recovery producing only 2% OOIP and the waterflood potential is not economically viable. Additional simulations have shown that the presence of gas cap and/or bottomwater is also detrimental to any polymer flooding scheme. The results also indicated that a polymer flood can produce oil at economic rates if the bottomwater zone or gas cap are of a limited thickness in comparison to the net pay. 

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