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GEOLOGICAL AND MINERALOGICAL SCIENCES
USE OF FOAM SYSTEMS IN THE DRILLING OF OIL AND GAS WELLS UNDER CONDITIONS OF ABNORMALLY
LOW RESERVOIR PRESSURES Deryayev A.R.1, Amanov M.A.2, Deryayev S.A.3 (Turkmenistan) Email: Deryayev573@scientifictext.ru
1Deryayev Annaguli Rejepovich - Candidate of Technical Science, doctoral Student; 2Amanov Mergen Annamuradovich - Senior Lecturer;
3Deryayev Suleyman Annaguliyevich - Student, DEPARTMENT OF OIL AND GAS WELL DRILLING, INTERNATIONAL OIL AND GAS UNIVERSITY, ASHGABAT, TURKMENISTAN
Abstract: improving the technical and economic efficiency of drilling of oil and gas wells is associated with usage of the most profitable types of drilling fluids. One of the main requirements for drilling fluids is increasing the drilling speed by economical use (expenditure) of chemicals and materials used for the preparation and processing of drilling fluids. Also, drilling fluids should not adversely affect the formation productivity. To eliminate the negative phenomena in the oil and gas deposits caused by both surface phenomena in natural conditions and due to the ingress of various media into the reservoir from the outside, complex reagent complexes have been created. One of the promising areas for solving this problem is usage of foam systems. Many years of pilot work carried out in oil and gas fields at abnormally low reservoir pressures proved high efficiency of foam systems.
Keywords: foam systems, abnormally low reservoir pressures, oil, drilling, absorption, drilling mud.
ПРИМЕНЕНИЕ ПЕННЫХ СИСТЕМ В БУРЕНИИ НЕФТЯНЫХ И ГАЗОВЫХ СКВАЖИН В УСЛОВИЯХ АНОМАЛЬНО НИЗКИХ ПЛАСТОВЫХ ДАВЛЕНИЙ
1 2 3
Деряев А.Р. , Аманов M.A. , Деряев CA. (Туркменистан)
'Деряев Aннагулы Реджепович - кандидат технических наук, докторант; 2Аманов Мерген Аннамурадович - старший преподаватель, соискатель; 3Деряев Сулейман Аннагулыевич - студент, кафедра бурения нефтяных и газовых скважин, Международный университет нефти и газа, г. Ашхабад, Туркменистан
Аннотация: повышение технико-экономической эффективности бурения нефтяных и газовых скважин связано с использованием наиболее выгодных видов буровых растворов. Одним из основных требований, предъявляемых к буровым растворам, является повышение скорости бурения путем экономичного использования (расходования) химических реагентов и материалов, используемых для приготовления и обработки буровых растворов. Также буровые растворы не должны отрицательно воздействовать на продуктивность пласта. Для устранения отрицательных явлений в нефтяной и газовой залежи, вызываемых как поверхностными явлениями в природных условиях, так и вследствие попадания в пласт извне различных сред, созданы сложные реагентные комплексы. К одному из перспективных направлений для решения указанной задачи относится применение пенных систем. Многолетние опытно-промышленные работы, проведенные на нефтяных и газовых
месторождениях при аномально низких пластовых давлениях, доказали высокую эффективность пенных систем.
Ключевые слова: пенные системы, аномально низкие пластовые давления, нефть, бурение, поглощение, буровой раствор.
Currently, one of the main problems in the world arising from drilling and development of wells is the absorption of drilling and cement fluids into formations. Huge amount of means and time is being spent on combating takeover. While solutions are absorbed during the drilling and operation of wells in production, a large number of complications arise. More precisely, a large number of chemicals and time are spent. Development of effective measures to prevent and control the likelihood of absorption will reduce the cost of developing fields, and will also increase the technical and economic efficiency of drilling of oil and gas wells. To solve these problems, it will be advisable to use foam solutions.
Low density of foams provides a significant reduction in hydrostatic pressure in the well, which creates favorable conditions for both effective destruction of rocks and for the qualitative development of hydrocarbon horizons. In addition, the flow of drill cuttings and other clogging materials into the reservoir is sharply reduced, which helps to preserve the filtration properties of reservoir. The above properties of foams can significantly reduce their absorption (filtration flow) until its complete elimination. This is also facilitated by certain colmatizing properties of foams due to the formation of adsorption films on the walls of the wells, as well as in pores and cracks, which prevent direct contact of the liquid with the rock.
Cleaning the bottom of the cuttings and bringing it to the surface is one of the functions performed by the flushing fluid in the process of opening the layer. As is known, clay solutions, aerated solutions, foams, hydrocarbon-based solutions and gaseous agents are used as washing liquids.
According to field data, as the density of the washing liquid decreases, the penetration rate increases. Speed of penetration also depends on degree of cleaning of the face from the cuttings. In turn, the cleanliness of face depends on both the fluid flow rate and its physicochemical properties.
Foam systems differ from other types of washing liquids in their physical and physicochemical properties, due to which they can change the density (0.2-0.9 g / cm3) in a larger range and have a high destructive ability [1].
In the process of drilling, forced stops often occur. In order to keep suspended rock particles in the annular space in suspension, the flushing fluid must have a holding capacity, i.e. thixotropic properties, for increasing in steady state over time, the ultimate shear stress. Unlike water and clay solution, the foam will keep particles of the cuttings in suspension for a long time due to structural and mechanical properties and phenomenon of fluidization. In this regard, the foam is far superior to all flushing liquids used.
Opening of reservoir by perforation is one of the most important processes in the system of measures for completion of wells. Foam solutions injected into the lower part of the well before perforation work include:
• Preservation of the natural permeability of reservoir;
• Prevention of deformation of the cement ring and production casing;
• Long-term existence of foam system in the column without changing its properties;
• Preventing mixing of the liquid located in the upper part of the column with foam.
Being a viscos-plastic elastic system, foam weakens the effects of shock waves generated during the shooting of perforators. This, in turn, can contribute more to maintaining the integrity of casing and cement ring.
Foam cement solution is a three-phase foam. In presence of cement particles, stability of the foam, as well as the strength of its bubbles, increases dramatically; stability of the foam increases with increase in adhesion strength of cement particles to air bubbles. The advantage of foam cement solution in comparison with conventional cement mortar is that the foam coverage area is significantly increased due to clogging properties, low density and elasticity of the system.
As the oil and gas field practice has shown, with the use of foam systems, oil and gas production can be intensified both by acting on formation and on the bottom-hole zone. The bottom hole formation zone is affected by chemical and physicochemical methods. In chemical methods, foam acid and foam clay treatments are used. In the first case, hydrochloric acid solutions are used, in the second - a mixture of hydrochloric and hydrofluoric acids [2].
In physicochemical methods, multicomponent foam is used. The advantage of the foam treatment is as follows:
• Due to its low density and high multiplicity, the foam acid covers a significantly greater thickness of layer;
• Due to high penetrating ability of the foam and the slower action of acid on the rock, it is possible to transport active acid deep into the formation over long distances, thereby exposing deep zones of the layer;
• Presence of a gas phase promotes better removal of reaction products from the bottom hole layer zone.
Long-term field tests indicate the possibility of intensifying oil production using foam systems in fields that have entered the late stage of development, characterized by low oil production rates and a high degree of water cut. The injection of a multicomponent system into the bottom hole formation zone gives positive results under the following conditions:
• Uncovered thickness of productive layers in the well is characterized by high heterogeneity in permeability - along with high permeability there are low permeability layers that are not developed during well operation;
• Low-permeability layers contain oil reserves that are not produced;
• Well is located in the zone of active exposure to water injected into injection wells;
• Water cut of well production is 95-99% and is characterized by high productivity.
Thus, our specialists set a goal, using local raw materials, to create an effective, affordable, cost-effective and environmentally friendly component composition that can be used to prepare a low-density drilling fluid, ensuring trouble-free wiring and completion of wells, in particular, when opening depleted wells horizons characterized by abnormally low reservoir pressure.
References / Список литературы
1. Mammedov В., Amanov М. Application of lightweight process fluids in well killing and workover operations. // "Education and sports in the prosperous epoch of powerful state". Articles of the International Scientific Conference, IV section. Ashgabat: Ylym, 2019. 348 p.
2. Mammedov В., Amanov М. Application of foam systems in drilling oil and gas wells in the conditions of abnormally low formation // "Education and sports in the prosperous epoch of powerful state". Articles of the International Scientific Conference, IV section. Ashgabat: Ylym, 2019. 350 p.
