Analysis of Solutions to Drilling Problems in Oil Extraction - Research Paper Example

Analysis of Solutions to Drilling Problems in Oil Extraction Countries that have oil reserves have a real treasure because the oil industry is a good boost to any economy. Some countries depend entirely on the oil industry for their livelihoods. Chemically, oil is a composite made up of carbon atoms and hydrogen bonded covalently. The world needs energy to drive each day’s activities and the oil industry is one of the sectors that the world depends on for a source of this energy. According to Al-Sowayegh (1984), statistics indicate that the industry provides seventy-five percent of the world’s energy. The oil industry serves several sectors of the energy generating industry. Some oil derivatives are in use in electricity generation, aviation, and heating houses. Moreover, other oil derivatives are important ingredients in the manufacture of beauty products and pharmaceutical products. With oil serving such important functions, maximizing its extraction by reducing cost of production is essential. This will ensure that oil gives high profits and that the world has sufficient energy supply. Before it reaches the utilization stage, oil must undergo production and drilling. There are multiple steps involved in the production. The procedure runs from producing the oil from the wells to the final stage that involves refining the oil to produce its derivatives in pure form. The extraction process involves a complex drilling process from the underground reserves. The drilling process involves drilling a hole deep enough to penetrate an oil reservoir in the underground layers. There are two types of drilling processes. One of them involves the vertical drilling procedure. The second type is the directional drilling which has proved to be a potential solution to most of the problems associated with vertical drilling. These problems include the excessive production of water alongside the oil, a case referred to as coning. According to Deskins, McDonald and Reid (1995), the coning problem in America has undergone 33% reduction through horizontal drilling. In both types, the drilling process presents problems that reduce the viability of the procedure and minimize oil productivity. Such problems include damage formation, sticking of the drill pipe and loss of circulation of drilling mud. Most of the oil extraction companies have adopted underbalanced drilling to solve the many drilling problems that have cropped up of late. This paper will address the drawbacks that are linked to drilling highlighting the effectiveness of underbalanced drilling and lost circulation materials as possible remedies to the problems. The drilling field presents two crucial definitions. These include the overbalanced and underbalanced drilling processes. These terms relate to connection of Hydrostatic Pressure (HP) of drilling fluid and the FP, which is gas and oil pressure formation. Cases whereby the HP proves higher than the FP indicate an overbalance. However, if HP is lesser in amount compared to FP, it is underbalanced (Bennion, Thomas and Bietz, 1994). The fluid used in drilling has a definition that regards it as mud made up of oil and water with chemical materials (Rabia, 1985). The drilling fluid has several functions. The mud ensures the cooling of the bit and drill string, and removes the cuttings out of the oil well. In addition, it renders protection from caving while controlling formation pressure (Rabia, 1995). Formation damage proves itself one of the major problems encountered in the drilling process. This poses a main challenge to the drilling process. According to Beatty et al (1993), and Jilani et al (2002), formation damage is a circumstance that reduces the productivity of a formation to give rise to oil and gas at the expected rate. The problem arises at varying degrees depending on the type of drilling and the resulting circumstances. In some cases, invasion by the drilling mud occurs as Beatty et al (1993) and Jilani et al (2002) describe. The drilling mud is a foreign fluid that gets into contact with virgin formation and usually has the capacity to give rise to damage. Jilani et al (2002) explains that most of the damage occurs at the pores of formation that are in the closest proximity to the well bore. Several solutions prove effective in minimizing the rate of formation damage and these include underbalanced drilling and stimulation of the operation. Stimulating operations involves two different parts. the first part focuses on acidizing while the second deals with fracturing. These are effective in reducing formation damage in both vertical and directional drilling operations (Jones and Davies, 1996). Before indulging in the stimulation procedure, there are essential studies that a company should consider. Schlager and Frick (1996) argue that the two stimulation operations can prove very effective in minimizing damage formation if the two important stages are in the right order. The first of these stages involves formation of oil and gas in damaged form and studies on this should be thorough. Studies should center on formation fluid and lithology. These studies will ensure selection of the best chemical materials. The second stage involves proper application of parameters such as pressures and volumes in the operation procedure. Failure to apply properly yields negative results. The mentioned stages define the treatment design. According to Schlager et al (1996), there is evidence from a field case that applying the right pressure greatly reduces the occurrence of formation damage. Underbalanced drilling, a term described above, offers the second viable solution to formation damage in drilling. It is applicable in both types of drilling procedures. In underbalanced drilling, it is possible to ensure that the hydrostatic pressure remains lower than the formation pressure (Rafique, 2008). A good illustration is the use of underbalanced drilling in drilling procedures in the oil well present in the Arabian Golf. The extractors are using underbalanced drilling in a bid to minimize formation damage (Qutob, 2004). The application of the solutions described above may present two major implications. In the first case, if careful application of the stimulating operations occurs coupled with proper planning of treatment, there will be partial reduction of formation damage and consequently, the well will prove more productive. Wahib et al (2010) present a good example of a case where the implication just described occurred. An offshore well-A received an acid treatment in 2009 after careful studies. Treatment occurred three times. As a result, the well produces 1529 oil barrels compared to 240 before treatment. In a second case, if adoption of underbalanced drilling occurs, there will be minimal formation damage, and this will imply a remarkable productivity of oil and gas (Rafique, 2008). A good example is evident in the well B-24, whose location is the Zueitina Oil field. In this oil field, drilling occurs via the underbalanced drilling method. The purpose of adopting the underbalanced drilling procedure was to ensure that there was limited formation damage. Consequently, there is great improvement and the oil field has recorded a 30%rise in production (Safaret, 2007). The above solutions cannot solve all the problems arising from formation damage. In most cases, the problems only have partial solutions. Stimulating operations has its limitations. It is more applicable in vertical wells. This is the case because there is a minimal interval of formation that ranges at about 300 feet. On the contrary, the interval in horizontal wells is greater and ranges between 300 and 3000 feet (Jones, 1996). This greatly limits the effectiveness of stimulating operations in horizontal drilling. In addition, the acid volume sufficient to deal with the damage ranges from 50-200 gallons per foot for vertical drilling. In a case involving horizontal drilling, that amount is insufficient. Therefore, it proves uneconomical for the horizontal drilling, as it requires more acid (Jones, 1996). Concerning underbalanced drilling, it proves a more viable solution for solving the problem because it is applicable before the operation reaches production of oil and gas.The application of underbalanced drilling by oil companies has presented desirable benefits and that explains why it is the choice of many companies currently. One of the advantages is that after the drilling process, treatment of the formation becomes unnecessary. This is the case because underbalanced drilling eliminates the damage that necessitates treatment (Rafique, 2008). In cases of extraction companies adopting underbalanced drilling, there is a noted five-fold increase in production. This is the case when comparing production rates in underbalanced drilling versus normal drilling (Rafique, 2008). A good example is clear from analyzing the effects of applying underbalanced drilling in eastern Middle East. Since the inception of underbalanced drilling, there is rise in gas production from 1.5MM cubic feet in a day to 5.2 cubic ft/ day as Qutob (2004), reports. Another merit is the fact that underbalanced drilling proves to have the potential of saving time and funds because it increases the penetration rate. Weatherford Company in Texas reports an increase of the rate of penetration through underbalanced drilling. The penetration increased from 40 feet in an hour to a twofold of 80 feet per hour (Rafique, 2008). Loss of circulation is the other problem that presents a challenge in the drilling process. The definition of the loss of circulation ranges from complete loss to partial loss of circulation of the drilling fluid (Rabia, 1985). Loss of circulation of drilling fluid may occur at any depth either in vertical or horizontal wells as long as the underlying causes are present (Fidan, Babadagli and Kuru, 2004). Analysis of the problem indicates that about a quarter of all drilled wells in the world usually face the problem of lost circulation according to Fidan et al (2004). Several factors are responsible for the occurrence of this problem. One of the leading factors is when the hydrostatic pressure of the drilling fluid is higher than the formation pressure (Rabia, 1985). When the hydrostatic pressure is higher than the formation pressure, three negative effects may result. The first negative effect may include a complete hindrance of all operations. Such hindrance implies delay in the drilling process leading to time loss and budget disruption (Rafique, 2008). The second effect may involve blowing out of the well and the company losing control of it as the hydrostatic pressure of the drilling fluid declines. In such a case, the drilling fluid reaches a low level in the well (Rafique, 2008). In an extreme case, the company may lose control of the well completely and such a situation compels the company to abandon it. There are potential solutions to the problem of lost circulation. The choice of the most efficient solution depends on the degree of loss of circulation. In some cases, there is only partial loss of circulation while extreme cases present complete loss of circulation. In addition, the type of formation affects choice of solution. According to Rabia (1985), the mixing lost circulation materials with the drilling fluid prior to pumping helps reduce the pores of formation in regions where loss of the circulation is likely to occur. Lost circulation materials include flakes and fibers. Cement may substitute lost circulation materials in some cases. Other options for lost circulation materials include chemical combinations H and F (CCH and CCF). These are essential in reducing loss of circulation. A good illustration is the case of an onshore well in Southeast Texas in which chemical combination H proved effective in reducing the loss of circulation (Whitfill and Hempfill, 2003). Underbalanced drilling is an additional solution that aids in reduction of lost circulation. This solution is applicable in the drilling procedure before the process reaches the stage of oil and gas formation. Due to the resulting low hydrostatic pressure that results, it is possible to establish a control of lost circulation (Rafique, 2008). A good illustration of the application of underbalanced drilling in reducing lost circulation is in Southern Mexico whereby of the well is 14,596 feet in depth and the FP 4,500 psi. In this well, lost circulation control is possible because underbalanced drilling hinders the occurrence of damage (Rafique, 2008). The aforementioned solutions have their varying implications. One of these implications involves the use of lost circulation material that aids in the closure of pores and hence minimizing lost cases of lost circulation. In South Texas, chemical combination H proves effective in reducing the occurrence of lost circulation. Before the application of the chemical combination, there was a marked loss of circulation of drilling fluid at 8100 feet. After the treatment, the problem of lost circulation reduced greatly from 100 to 20 barrels of drilling fluid in an hour (Whitfill et al, 2003). In addition, the rate of productivity increases greatly when underbalanced drilling comes into place. Underbalanced drilling in southern Mexico proved successful by preventing loss and increasing productivity (Rafique, 2008). However, the aforementioned solutions do not address the problem of loss of circulation completely. The chemical solutions used as lost circulation materials only come into place when the loss occurs. In more than a thousand cases under analysis, use of chemical combination F proved successful in solving the problem after several trials of natural lost circulation materials failed. It is worth noting that in these cases, trials of using cement to solve the problem had failed (Whitfill et al, 2003). The possibility of selecting an appropriate lost circulation material comes only at a later stage and this makes it a disadvantage. In addition, the mixing of the right volume of lost circulation material needs caution. Sometimes the effectiveness may be low because of little volume of the lost circulation material. On the other hand, using too much of the lost circulation material leads to remnants of the material in the well. These remnants make the well subject to erosion (David and Catalin, 2003). The application of underbalanced drilling proves to be superior to the other solutions. This is because it has several advantages. Its main advantage is the fact that it ensures that the hydrostatic pressure is not more compared to the FP. In this case, the formation fluid will get access to the well and no loss will occur. A second advantage is that in underbalanced drilling, treatment of formation is unnecessary (Rafique, 2008). Because of these advantages, there is a markedly higher productivity of oil and gas. Safer et al, 2007 asserts that in Libya, a well drilled to minimize loss by underbalanced drilling has led to an increased the well’s productivity. Nevertheless, underbalanced drilling is a solution only in the production of gas and oil because the use of nitrogen in completion of the drilling process presents extra expenses (Bennion et al, 1994). From the elaborations given above, it is evident that the drilling procedure has associated problems that pose a great challenge to the oil extractors. Although there are efforts to help end these problems, it can be argued that these problems will still continue existing. Some of these problems include formation damage and lost circulation of drilling fluid. However, there are possible solutions to such problems. Stimulating operations and lost circulation materials are possible solutions but they have limited efficiency. Underbalanced drilling proves to be the most superior of all solution and results to reduced problems and increase of yield in the oil wells. Therefore, it is the best solution for countries that have large oil reserves. References Al_Sowayegh, A. (1984). Arab petropolitics. London & Canberra: Croom Helm. Beatty, T., Hebner, B., Hiscock, R., &Bennion, B. (1993). Core tests help prevent formation damage in horizontal wells. Oil & Gas, 91(31), 64-70. Bennion, D. B., Thomas, E. B., Bennion, D. W., &Bietz, R. E. (1994). Underbalanced Drilling and Formation Damage - Is It a Total Solution? 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