Reservoir section

The reservoir section is more consolidated and is the main objective to which the well is being drilled, hence the drilling process has to ensure that any productive interval is not damaged. 

Between the top hole and the reservoir section in most cases an intermediate section will need to be drilled. This section consists of more consolidated rocks than the top hole. The deviation angle is often increased in this interval to reach the subsurface target and eventually a casing is set prior to entering the reservoir sequence. 

Wells may be drilled at a constant angle to the target or dropped off to a lower angle through the reservoir section. To build, maintain or drop the deviation angle stabilisers are run in the bottom hole assembly (Fig. 3.15). A change in deviation used to require a round trip to change the position of those stabilisers in the bottom hole assembly. In recent years, adjustable, hydraulically activated stabilisers have been developed. The... 

Other logs employed to determine N/G ratio include the spontaneous potential (SP) log and the microlog, which differentiate permeable from non-permeable intervals. The N/ G ratio can also be measured directly on cores if there is visible contrast between the reservoir and non-reservoir sections, or from permeability measurements on core samples, providing sample coverage is sufficient. 

This is the method used by the commercial software packages Crystal Ball and RISK . The method is ideally suited to computers as the description of the method will reveal. Suppose we are trying to combine two independent variables, say gross reservoir thickness and net-to-gross ratio (the ratio of the net sand thickness to the gross thickness of the reservoir section) which need to be multiplied to produce a net sand thickness. We have described the two variables as follows ... 

When the tube was operated as a shock tube (i.e. when detonation was initiated from a shock), a diaphragm of cellophane or photographic film was inserted in the union along with an Oring to seal the test chamber. To burst the diaphragm compressed He or H was fed into the reservoir section until rupture occurred. The burst pressure was read from... 

Basin lead to oxidation of the sediments (Schroeder et al., 2002). Such a process has already occurred at Kesterson Reservoir (Section 9.02.7.4.1). The change of land use, for example, from wet paddy soils to dryland agriculture, could also lead to an increase in uptake of selenium by crops (Yang et al, 1983). 

The main block-bounding normal faults of the Oseberg Syd region have throws in the range of 200-500 m in the reservoir section (the Brent Group). The following structural elements are defined by these faults (Fig. 2) ... 

Fig. 8. Flow system for adsorption studies a la Wagener (12). F—sample surface B—gas bulb. Gas density in reservoir section measured by ion gauge IR, and controlled at a constant setting Nt by adjusting valve V. Density N in cell measured by gauge In. (jV —N)Se = net flow into cell determined by capillary A, with pumping speed SE.

Filling of the reservoir sections from the fault would occur until there is equilibrium between... 

Traps in the western Haltenbanken region like Lavrans, Kristin, Trestakk and Smorbukk contain mainly petroleum of high maturity, yet in the compartmentalized Smorbukk field some medium maturity bitumen remains in particular reservoir sections. This is most likely due to strong compartmentahzation caused primarily by the lithological heterogeneities and secondarily by diagenetic poroperm modifications. 

Because the water cut increases sharply as production continues in time, the measures to block and isolate formation water must be employed in a discriminatory fashion. When, at a particular point during the production from reservoir sections of macroporosity type, it becomes necessary to isolate formation water, it must still be remembered that the same high permeability channels that must be blocked may later have to be used again to inject different agents, such as steam, to stimulate production fix>m adjoining sections of the reservoir with rocks of microporosity... 

The data discussed above indicate that during the primary production from the Zybza field, the application of the customary stimulation techniques based on geological characteristics of the reservoir, as a rule, failed to increase the rate of petroleum extraction and the oil recovery factor. History of oil production at the Zybza field showed that only the reservoir sections of macroporosity type were effectively exploited. The reservoir rocks of microporosity type did not yield their petroleum in spite of the application of the then known and proven methods of reservoir stimulation. 

To overcome these shortcomings, steaming by block-cyclic technique has been developed at the Zybza field through both experimental work and field testing. In this variant of steam soak, separate closed and relatively stable high temperature fields are created by the thermodynamic process. Each one of these fields encloses a descrete block of the petroleum reservoir. Each field is confined within pre-selected boundaries beyond which the heat front does not extend. This method insures both maximum distance of penetration by the heat carrier into the individual reservoir sections of microporosity type and high oil recovery factors for this type of reservoir. 

First, a discrete block is selected in an oil field which is made up mostly of reservoir sections of microporosity type and of some sections of macroporosity (fracture porosity) types. Next, wells are drilled into this block at close spacing of not more than 100 m either on a checkered grid or in rows. The cyclic steaming of the reservoir block follows according to a pre-set plan. With the arrangement of wells in rows, steam is injected into the second line of wells. The row of production wells is in the middle. 

Breakthroughs of injected steam into nearby wells through macroporous, high permeability sections of reservoir with resulting limited penetration and heating of microporous reservoir sections in the bottomhole zone of treated wells 21... 

A common observation concerning oil inclusion abundance is that paleo-oil columns are common not only below current oil columns, but also in wells that are completely dry at present. For example, in the Timor Sea region of northern Australia, there was an extensive period of fault-seal breach of oil reservoirs during Late Miocene/Early Pliocene fault reactivation, and this left many paleo-oil columns in the presently water-filled reservoir sections [28,128]. In dry wells, the analysis of fluid inclusion oils offers the possibility of understanding a petroleum system without having access to current fluids in the reservoir [49,55,129], and potentially then being able to predict where the oil may have leaked to, or where it may be trapped in nonbreached structures. 

Experimental Techniques and Pitfalls. The volumetric technique is the most commonly used method for measuring high-piessnie isotherms (Yang, 1987). The apparatns involves a sample cell and a reservoir section. A pressure drop is measured when the piessnrized reservoir is connected to the evacuated sample cell. The dead volumes of both compartments are measnred by helium displacement using ideal gas law. Any additional piessnie drop over that of He is atuibnted to adsorption. The amonnt adsorbed can be obtained from the dead volumes and a P-V-T relationship. Desorption can be measured by reversing the process. 

As in the case of thermal conduction, we can relate the entropy exchange to the inflow of A and outflow of B due to contact with the chemical reservoirs. Section... 

Now consider the role of polymer flooding in more realistic areal and vertical reservoir sections which are taken to be approximately two-dimensional (2-D) in nature. In a homogeneous areal system, the situation is similar in certain respects to the 1-D case discussed above. At lower M values, there is very good microscopic displacement and good areal sweep. 

An example of this design approach is the Li/S02 reserve battery illustrated in Fig. 20.5. The battery is cylindrical and contains three main components (1) the electrolyte storage reservoir section, (2) the electrolyte manifold and activation system, and (3) the reserve cell compartment. About one-half of the internal battery volume contains the electrolyte reservoir. The reservoir section consists primarily of a collapsible bellows in which the electrolyte solution is stored. Surrounding the bellows, between it and the outer battery case, is a space that holds a specific amount of gas/liquid. The gas is selected such that its vapor pressure always exceeds that of the electrolyte, thereby providing tbe driving force for eventual liquid transfer into the cell chamber section once the battery has been activated. 

A total of 24,214 rural migrants in the Chongqing reservoir section had voluntarily displaced their families and resettled in 27 provinces nationwide (including Chongqing) by the end of 2004. The majority (18,074 persons) of them were resettled in Hubei, while 4,983 were settled in other provinces and 1,157 in non-flooded counties within Chongqing. This spontaneous mobility to locations beyond the reservoir area started mainly from 1996 to 1999. However, these migrants (15,898 persons) displaced (mainly to Hubei) at an earlier time have suffered much stress owing to some major constraints connected to their displacement. 

The core component of the GODR approach is to move some 137,000 rural migrants from the nine counties/disfricts in the Chongqing reservoir section. Scheme (1) involves the rural migrants from eight counfries/districts (Wanzhou,... 

Origin county/district Out of Chongqing reservoir section Within Chongqing reservoir section ... 

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