Hole Pump Research Articles

Development of a large capacity cryopump equipped with a two-stage GM cryocooler

• A 20-inch cryopump including a two-stage GM cryocooler has been developed. • Design methodologies behind the GM cryocooler and cryopump have been addressed. • The cooling capacities of the GM cryocooler exceed 80 W and 8 W at each stage. • The pump captures N 2 with 11,000 L s −1 and endures gas impulse of 2,500 mbar L. • The pump can evacuate down to ultimate pressure of 10 -9 mbar-class. Cryopump, which involves the removal of gas by cryo-sorption, condensation and solidification onto cryo-panels, is an ideal form of ultra-high vacuum (UHV) pump due to its contamination-free operation and black hole pumping speed. The high crossover of the cryopump can provide a clean vacuum environment. Since the cryopump utilizes the cryo-pumping effects mentioned above, a cryogenic environment is a prerequisite condition. In this research paper, a 20-inch cryopump, which is driven by a two-stage Gifford-McMahon (GM) cryocooler, is developed and tested. The GM cryocooler is designed by optimizing the opening timing of the rotary valve, and the corresponding thermal losses at its each stage have been analyzed. Under the thermal loads of 80 W and 8 W at each stage of the GM cryocooler, the temperatures are measured to be 66 K and 19.5 K, respectively. The cryopump is designed with the aspect of heat transfer assessment. The model described in this paper considers two major thermal loads; radiative heat ingress and enthalpy transfer by the existence of the gas. This simple model can readily predict the thermal loads on each stage of the GM cryocooler. Since all the cryo-panels are kept below 130 K during operation, the cryopump that has been developed is therefore compatible with a UHV pump. Using nitrogen gas, the ultimate pressure, pumping speed and crossover are measured to be 9.9 × 10 -9 mbar, 11,000 L s −1 and 2,500 mbar L, respectively. Through the experiments, it is also concluded that the numerical model above can explain the thermal characteristics of the cryopump reasonably well. The cryopump will be able to respond to the market needs of the large-size display and semiconductor manufacturing processes as well as increase its energy saving and process operability. Furthermore, the reliability of the GM cryocooler can also be improved through turndown operations.

Technological features of pumping water into high-viscosity oil injection wells with the bottom hole pump

The authors laid bare a correlation between the proportion of mechanical contaminations and oil products in discharge waters and the average oil viscosity in the field. Film thickness depends on the oil viscosity. More viscous oil forms thicker and heavier films on the surface of suspended solids. The use of electrical centrifugal pumps for fossil water injection into the well allows using the heat produced by the pump to warm the water. Standard measurement instruments show that the change of injected water temperature at the head of the well pump-over unit is between 1.1 and 8.4 °C. The average temperature increase is 3.6 °C.

Design of multi-parameter auto-detecting instrument system for hydrological hole pumping test based on single-chip microcomputer

In order to meet the requirements of modern hydrogeo-logic investigation, one multi-parameter auto-detecting instrument system for hydrological hole pumping test based on single-chip microcomputer is designed. The pumping test system contains one lower computer module and one upper computer module. The lower computer module uses the STM32 single chip microcomputer as the central module of the controller, supplemented by the sensor module, the power module, the communication module and the display module to realize the automatic detection of the multi-parameters of the hydrological hole pumping test It can display the information of pumping speed, water level, water temperature and water flow in real time and realize the function of pumping timing switch. The upper computer module allows users to check hydrological hole pumping test information and control the whole system operation. The information transmission between the lower computer module and the upper computer module is completed by Narrow Band Internet of Things (NB-Iot). By analyzing the data of pumping test system after compensation, the max relative error of liquid level is all less than 1%. All these data confirm that the pumping test system proposed in this paper has certain application value.

Safety enhancement during deep well pump replacement

In Ukraine, as in other countries of the world, the majority of oil wells are operated using a mechanical method of production, such as rod well pumping method, containing above-ground and underground equipment. For repair or replacement of underground equipment (down hole pump), is brought to the surface. In this case, the well may have oil-water gas inflow caused by the «piston» effect, for example. (Substitution of volume between the pump and the pump rods by fluid from the formation). This could lead to an open flowing well. Many additional complex operations are used to perform safe well workover operations, such as well closure. These operations are performed to control well formation pressure, prevent gas-oil and damage to downhole equipment. It is also worth paying attention to the fact that disruptions in the process of well closure can lead both to a decrease in its productivity and to the complete termination of its operation. To prevent oil-water gas inflow various equipment and devices are used: Cameron ram-type blowout preventer, wellhead stuffing boxes, emergency washers with gate valves, downhole shutoffs, downhole check valves. All this increases safety when replacing downhole equipment, but does not guarantee the avoidance of additional complications in the operation of this equipment: the possibility of controlled shutdown of the well, recovery of oil production without performance of downhole operations, etc. To eliminate these complications, a downhole check valve design was developed. Its design allows: not to change the arrangement of elements in the well; to change the pump without well closure (it reduces repair time and costs); undercut tubing (does not allow the fluid from the formation to enter the well and create an emergency situation that could lead to open well flowing).

Analysis of comparative and dimensionless characteristics of centrifugal pumps for water injection into the oil reservoir

The paper reviews the existing references on set task. The general issue on the importance of produced water injection into the wells, the static indexes of pumps used for water injection into the formation are considered, via the general data on modelling theory (similarity), the characteristic parameters of electric-centrifugal bottom hole pump studied as well. Comparative, dimensionless and operational characteristics of ETPК type pump were found on set table data in the active use of similarity theory. The list of used references is provided.

Lined tubing performance in CSG wells operated in Australia

One of the major challenges with progressive cavity pump (PCP) applications in Australia is the production of highly concentrated solids. Large volumes of solids entering the production string cause both high torque issues and holes in tubing, resulting in lost production and the need for intervention with a flush-by unit or service rig. On account of these issues, it is reported that up to 40% of PCPs in the Australian coal seam gas (CSG) fields can be down at any given time. Coho Resources has introduced lined tubing as an engineered solution. The proprietary lining the tubing has a lower friction factor compared with conventional steel tubing, resulting in lower operational torque and reduced operating costs. The added lubricity from the lower friction coefficient in lined tubing allows solids to flow more freely to surface where they are captured and discarded from the system. Lined tubing allows producing companies to realise bottom-line operational savings in several ways. The largest of course is minimal downtime and reduced well service costs due to the elimination of our previous tubing related problems. With reduced work over costs, savings become visible very quickly. Rig costs, bottom hole pump, tubing and sucker rod replacement costs are all reduced. Application of lined tubing in CSG wells in Australia results in: • 15–25% less torque on the drive system, • An 70% increase in run times between workovers (lined tubing versus un-lined tubing), and • Compatibility with existing field equipment and handling methods.

Self-trapping and ordering of heavy holes in the wide band-gap semiconductor β−Ga2O3

Scanning tunneling microscopy (STM) has been utilized for imaging and manipulation of self-trapped holes on the surface of the wide band-gap semiconductor $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$. A positively charged surface layer comprised of localized holes with ${10}^{13}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$ density has been observed for $n$-doped samples. We show that the surface layer can be populated by hole pumping from the STM tip. A transition between the glassy phase and ordered striped phase of self-trapped holes has also been observed. Our analysis indicates that the saturated two-dimensional density of self-trapped holes may be determined by balance of self-trapping and Coulomb repulsion energies.

THE CHOICE GROUND OF DOWNHOLE STREAM PUMP GEOMETRICAL SIZES

The method of choosing geometric parameters of the well hole pump which ensures its operation in the mode of maximum efficiency is proposed. According to the algorithm developed, the ratio of the diameters of the working nozzle, the mixing chamber and the diffuser of the jet pump, as well as the distance between the nozzle and the speed equalization chamber and the axial dimensions of the flow part elements are regulated. During the process of establishing the required dimensions of the elements of the ejection system, the nature of the free working jet into the mixing chamber of the jet pump is taken into account, which determines the shape and structure of the estimated ratios governing the axial distance between the working nozzle and the resuscitation chamber of the mixing streams. The relationship between the mixing chamber diameters and the working nozzle and the amount of the jet pump coefficient of ejection which ensures its operation with the maximum possible values of the ejection system efficiency is shown. The analytical nature of the establishment of hydraulic interconnections among the elements of the ejection system is complemented by the experience of the practical use of deep jet pumps in the implementation of certain technological processes of construction, operation and repair of oil wells.

Plasma Reinforcement of Working Surfaces of Parts of a Bottom Hole Pump

Plasma Reinforcement of Working Surfaces of Parts of a Bottom Hole Pump

Well extension in fractured and broken rocks by wire-line tool (SSK-59)

Conditions of increasing the drilling rate per run, which influence wire-line tool application efficiency, are analyzed. Decreasing of drilling rate is usually caused by alarm initiation which indicates core blocking. Producing of longitudinal and lateral vibrations during drilling process and initiation of fluid upward flow inside the inner core pipe, significantly increases the drilling rate. For initiating an upward flow inside the inner core pipe it is suggested to install the bottom hole pump inside the wireline inner core barrel to be applied as a mechanical motor of downhole vibrator which starts to operate only in a case of core blocking. It was found out that the bottom hole pump provided the necessary speed of upward flow (0.3 - 0.5 m/s) at the rotation speed of more than 150 rpm. Field test was carried out to drill siltstone and sandstone formations of 9 -10 drilling category and their alternation with the formation dip angle of more than 70° (rough and disintegrated rocks). The upward flow inside the inner core pipe SSK-59 allowed increasing the drilling rate by 10% as well as to increase core recovery ratio. Besides, it was noted that a large amount of the cuttings (sized 8 - 10 mm) were accumulating inside the inner core pipe during downhole pump application, that in its turn, proved the initiation of upward flow inside the inner core pipe.

Permeability Improvement Technology of Directional Hydraulic Fracturing in Low Permeability

According to the conventional fracturing could easily lead to the local stress concentration of coal, the effect of pressure relief and permeability improvement is not ideal. The mechanism of directional hydraulic fracturing is analyzed and the parameters such as the layout of directional hole, the fracturing hole sealing, the minimum cracking pressure are discussed, then the field application tests are carried out. The results show that the directional hydraulic fracturing effect is better than that of ordinary fracturing hole and the maximum concentration and the average drainage scalar is respectively 3.75 times and 4 times of the ordinary hole pumping gas fracturing effects. The effect of permeability improvement is remarkable.

Phonon-pumped SiGe-Si interminiband terahertz laser

The first phonon-pumped semiconductor laser has been proposed and theoretically investigated. The active region is an unbiased boron-doped Si/sub 0.94/Ge/sub 0.06/-Si superlattice with Si/sub 0.97/Ge/sub 0.03/ buffer layers embedded in a surface-plasmon strip waveguide. Warm and cool heat sinks create a temperature gradient across the waveguide. A heat buffer layer adjacent to the cool sink reflects optical phonons and transmits acoustic phonons, Within the resonator, the difference in effective temperatures of optical and acoustic phonons provides hole pumping for the lasing transition between the heavy-hole 2 (HH2) and heavy-hole 1 (HH1) minibands. A gain of 280/cm at the 5 THz emission frequency is predicted for 6/spl times/10/sup 17//cm/sup 3/ doping at temperatures of 300 K and 77 K for optical and acoustic phonons, respectively. A range of operating conditions in phonon-pumped IV-IV, III-V, and II-VI materials appears feasible.

Paleofluids and Recent fluids in the upper continental crust: Results from the German Continental Deep Drilling Program (KTB)

The two German Continental Deep Drilling Program (KTB) boreholes provided samples for studies of fluid inclusions (paleofluids), “free fluids” of the crystalline basement, and their fingerprints on the chemical and isotopic composition of minerals and rocks to 9101 m depth, which allowed reconstruction of the evolution of fluids, their migration pathways, and their sources. Aqueous fluids were largely lost during the Devonian amphibolite facies metamorphism. Thereafter, radiogenic, nucleogenic, and fissiogenic gases, together with NH4‐fixed nitrogen, were released from host rocks and partly enclosed in secondary inclusions. During the Hercynian uplift, Na‐Cl fluids (formation water) infiltrated and dissolved noble gases and N2 largely originating from the host rocks. In the course of the Cretaceous denudation, high‐salinity Ca‐Na‐Cl brines, possibly derived from Permo‐Carboniferous sediments but altered by fluid/rock interaction, migrated into their present position. This fluid introduced low‐maturity hydrocarbons released together with nitrogen from early metamorphic organic‐rich sediments. The 4000‐m fluid from the KTB pilot hole pumping test, which was analyzed chemically and isotopically, seems to be a mixture of an ascending basement brine and a descending paleometeoric water, from which the late alteration minerals calcite and laumontite precipitated in fractures. The calcite is neither chemically nor isotopically in equilibrium with the recovered “free fluid.” Hydraulic tests indicate a communicating system of fractures between the boreholes with a distinct matrix and fracture porosity.

Practical Decline Analysis Part 2-Identification And Quantification of Development Opportunities

Introduction This paper is the second of a two-part discussion on decline analysis. The first part in last month's issue presented a discussion of decline methods and theory as well as a review of limitations of the methods and rules to avoid misinterpretations. This second part presents various interpretation techniques to identify production problems and development opportunities. Identification and Quantification of Development Opportunities The most reliable way of quantifying development opportunities is to compare recovery factors derived from decline extrapolations with theoretical recovery factors. When reserves derived by decline analysis fall short of theoretical values, a development opportunity exists. Other means of identifying development opportunities is from a review of the character of the production history. Observations to consider in various types of reservoirs are described below: Solution Gas Drive Oil Pools Increase in oil decline rate without significantly increasing GORs Declining oil rates and increasing GORs are expected in a solution gas drive reservoir as pressure declines. If oil rates fall without increasing GORs the decreased productivity is likely caused by inefficient bottom hole pumping conditions or formation damage rather than pressure loss. A bhp change or wellbore stimulation may therefore be warranted. An approximate quantification of the incremental reserves associated with the remedial action would be the difference between the current decline extrapolation and a previous extrapolation prior to the wellbore problem. A comparison of a well's decline behaviour with offset wells in the same pool is often useful in identifying wellbore problems. Shallow or harmonic decline trends Shallow or harmonic decline trends indicate either low permeability, wellbore damage or large reservoir size. In either case, workovers or additional drilling should be examined to at least shorten the reserve life of the pool. Water Drive Reservoirs Declining fluid rates Declining fluid rates in water drive reservoirs is usually caused by inefficient bottom hole pumping conditions or formation damage. A bhp change or wellbore stimulation may therefore be warranted. An approximate quantification of the incremental reserves associated with the remedial action would be the difference between the current oil rate decline extrapolation and the oil cut decline extrapolation. Shallow or hannonic decline trends where recovery is governed by water coning Shallow decline trends after water breakthrough indicate either low permeability or large reservoir size. In either case, additional drilling should be examined to at least shorten the reserve life. Harmonic decline trends typically indicate that interference between producing wells is not occurring. Infill drilling should therefore be examined. Incremental recovery associated with such a program should be rationalized volumetrically considering the shape of the cones. Waterfloods Declining fluid rates As in water drive reservoirs, declining fluid rates may be caused by inefficient bottom hole pumping conditions or formation damage which can be resolved by either bhp changes or wellbore stimulation. An additional cause could be bottom hole pressure declines resulting from insufficient voidage replacement. In such instances, injection rates and voidage calculations should be rechecked and an examination made for potential 'thief zones.

Application of Artificial Neural Network to Pump Card Diagnosis

Abstract Beam pumping is the most frequently used artificial lift technique. Down hole pump cards are used to evaluate performance of the pumping unit. Pump cards can be generated from surface dynamometer cards using one-dimensional wave equation with viscous damping, as suggested by Gibbs. Pump cards contain significant information describing the behavior of the pump. However, interpretation of these cards is very tedious and time consuming. Hence, an automated system capable of interpreting these cards is very useful. This work presents a DOS based computer program capable of correctly classifying pump cards. The program uses a hybrid artificial neural network (ANN) to identify significant features of the pump card. The hybrid ANN utilizes classical and sinusoidal perceptrons. The network is trained using error back propagation technique. The program has been able to correctly identify problems in over 100 different training and test pump cards. The ANN requires total of 80 data points as input. Sixty data points are collected from the pump card perimeter itself and the remaining 20 data points represent the slope at selected points on the pump card perimeter. The problem conditions are grouped into distinct classes such as malfunction anchor tubing, fluid pound, gas interference, and worn traveling valve. The network is capable of identifying one or more of these problem conditions for each pump card. Several examples will be presented and discussed. Introduction Sucker-rod pumping system is a very popular means of providing artificial lift for wells. It is estimated that 90 percent of artificially lifted wells use sucker-rod pumping systems. In order to assure proper operation of these systems it is necessary to monitor them on a regular basis. This is done by means of a dynamometer which is attached to the polished rod of the pumping unit. The plot of load versus position generated by the dynamometer is known as a surface card. Using the technique proposed by Gibbs this surface card can be used to obtain down hole "pump card". The pump card presents the load versus position at the pump down hole instead of the load versus position at the polished rod on the surface. The shape of the pump card can be used as a diagnosis tool. For example, when the pump is functioning properly and pumping to its full capacity the pump card will have a rectangular shape. When the pump capacity is not being fully utilized then we may have a condition called "fluid pound". The petroleum industry is in the process of automating the control of pumping wells. Computers are being used to continuously monitor the pump and transmit data to a central office for further analysis. The shear volume of data received makes it necessary to develop tools for automatic analysis of the pump cards. Various pattern recognition techniques have been used to analyze the down hole pump card. Traditional techniques require significant processing time. P. 151^

Periodic motions of sucker rod pumping systems

AMONG the most important of the artificial lifting methods used in petroleum industries are the sucker rod pumping systems. In order to improve the design and the operation of such installations, it is necessary to understand their behavior, especially at infield situations. The pumping system is put into action by an engine that imparts a periodic motion to the top of the rods, and eventually all of the system sets itself in a periodic motion. To describe this behavior, several mathematical models have been developed over the years by taking into consideration various inertial and dissipation effects in the system, material properties, down hole pumping conditions, fluid interactions, and so on (see for instance Doty and Schmidt [l]). Obviously, several nonlinearities are present in the problem, but there is one that is intrinsic to the pumping system itself. This is due to the presence of the valve mechanism that imposes sudden changes in the stress acting on the rods according to the opening or the closing of the down hole and walking valves. Concerning the study of these models, some theoretical analysis has been done in certain linearized versions of the models, and many numerical experiments were performed. In general, however, there is a lack of sound mathematical analysis of the nonlinear models. In this paper we consider a simple model that takes into consideration the elastic response of the rods, the dissipation mechanism (due to internal material dissipation and hydraulic friction) and the stress change due to the valve mechanism. It corresponds to the same partial differential equation used in Pavlik and Schafer [2], it is a wave equation with dissipation, but with a nonlinear and discontinuous boundary condition modeling the action of the valves. Our objective is to study the interaction between the action of the valves with the periodic motion imparted by the engine on the top of the rods in the production of the final motion of the rod. We are able to show the existence of a strong forced periodic solution for the mathematical model of this problem in the following way: we first show that the operator associated to the problem is maximal monotone in a convenient Hilbert space. Thus, we are in the setting of the well-known theory of monotone operators, but we cannot apply its standard results on periodic solutions because our operator is neither strictly monotone nor coercive. The main difficulty is to control the influence of the boundary conditions. We then proceed by approximating our equation in a suitable way by equations for which the corresponding operators are strictly coercive; for them the standard theory can be applied, and approximated periodic solutions are obtained. We then strive to obtain certain estimates for these approximated solutions, which permit us to conclude that they approach a mild periodic solution of the original problem. An essential step for this is the construction of an adequate Liapunov function that furnishes an

Design and Diagnosis of Deviated Rod-Pumped Wells

Summary A wave equation method is presented for the design of deviated rod-pumped wells. Applications made to wells involve bare rods, molded-on guides, and wheel-rod guides. The design method is also used to explain the type of errors that result when vertical-hole techniques are used to compute down hole pump cards in crooked wells. Introduction Commonly used methods for designing rod-pumping installations presume vertical wells. This paper introduces a wave equation methodology that applies to deviated wells, whether they are deviated intentionally or unintentionally. Restrictions on surface locations and interest in horizontal drilling are increasing the need for deviated wells. Together with long-standing crooked-hole problems, these are promising subjects for further study. This paper describes a predictive method that applies to 3D problems. A well deemed too crooked to pump is studied, and a procedure for designing intentionally deviated wells is presented. The relative friction effects of rod guides are discussed, and the effect of borehole path on power consumption is treated. The concept of dogleg severity is examined and deemed inadequate as a measure of difficulty in pumping deviated wells. The types of errors that result when vertical-hole diagnostic methods are applied to deviated holes are discussed. Finally, a new formulation of the radius-of-curvature concept is derived together with techniques for deducing rod-tubing friction from dynamometer valve checks. Comparisons with actual measurements are included to validate the methods. Deviated wells can be adequately designed with wave equation methods, and highly deviated wells can be produced with rod-pumping equipment when care is taken to control the path of the borehole. This paper should be considered as a progress report because much remains to be learned about the application of this technology.

Computer Model Evaluates Oil Pumping Units in Inclined Wells

Abstract The paper analyzes the dynamic behaviour of the sucker rod string in the inclined well. In this case, due to the curvature of the tubing the rod vibrates longitudinally as well as transversally. A mathematical model of the vibrating string consisting of two coupled differential equations was developed. The paper describes the fundamental assumptions and simplifications which can be used in the numerical analysis. The examples of the results are also presented. They include the effect of the distortion of the geometry of the rod string on the plunger load-displacement diagram and the diagram of the friction forces along the rod string. Introduction The evaluation of pumping units in the inclined wells has been a serious problem in engineering practice. The common practice at present is the application of the program developed for vertical wells to the analysis of deviated wells. This introduces substantial errors in the calculations of the stresses in the rod string and as regards the gearbox torques. Generally, the maximum torques calculated properly for the actual geometry of the slant hole pumping unit can be up to 40% larger than the corresponding values obtained from the calculations for vertical units. Besides, the application of the program for vertical wells to the evaluation of inclined, wells gives results in which all the friction forces from the rod string are concentrated at the plunger. This gives false prediction of high compressive forces at the bottom of the rod string and can be the reason for the wrong conclusions regarding the rod stability. The rod in the inclined well is under different static and dynamic forces than in the vertical one. It is supported by the tubing of wheeled couplings but it is also transversely loaded by its own weight. Therefore, the dynamic behaviour of the sucker rod in the deviated well is much more complicated and different from a vertical one. The differences are caused by the friction between the rod string and the tubing and the rod curvature. If the tubing is curved, the dynamically loaded rod string deforms and comes into contact with the wall of the tubing. The curvature causes the lateral displacements of the rod inside the tubing. It couples the longitudinal vibrations with the transverse vibrations. The axial compressive forces at the bottom of the well can buckle the rods. In this case, the problem becomes nonlinear and difficult to solve. The need to obtain a model for use in the evaluation of pumping units and downhole equipment in the inclined and deviated wells resulted in the development of an applicable design and optimization technique. SRPUMP computer program was developed a tool that allows a high level of expert knowledge to be applied daily in the field, dealing with problems of the inclined wells. Fundamental Assumptions An accurate prediction of the performance of the sucker rod string and the bottomhole equipment requires careful modelling of the dynamic behaviour of the rod.

The Electrothermic System for Enhancing Oil Recovery

AbstractThe problem with the production of heavy oil is basically related to its heavy viscosity, the matter which results in its slow flow into an oil well and also in the difficulty of its pumping to the surface. One solution to this problem is the addition of heat to the oil flowing. A rough rule-of-thumb for most heavy oil is that heating the formation by about 5°C would cut the viscosity of the oil to half of its original value and, likewise, increase the flow rate by a factor of 2. The electrothermic system is designed to increase the flow rate of oil by accomplishing the following tasks: (1) Heat the entire flow string plus the down hole pump and pump rods so that the pump will work more efficiently and the viscosity of the oil in the flow string will be greatly reduced. (2) Heat out into the oil reservoir to a considerable distance from the wellbore, thereby increasing oil flow into the wellbore because of reduced viscosity. (3) The system also moves water away from a producing wellbore, thus incr...

Specialized Pumping Techniques Applied to a Very Low-Gravity, Sand-Laden Crude - Cat Canyon Field, California

Summary With the application of specially designed pumping and treating equipment, we are producing crude oil as low as 4°API (1.044 g/cm3) containing up to 70 vol% of sand. An important part of this system is the bottom hole pumping equipment that has allowed primary production rates in excess of 150 B/D (24 m3/d) oil from wells that were restricted to less than 10 B/D (1.5 m3/d) oil when produced with conventional rod pumps and sand control completion methods. These pumps are available commercially. Techniques developed may be extended to other areas where production is limited by problems inherent with highly viscous crude oils and excessive sand entry. Introduction Problems with pumping extremely viscous crude oils are well known to all operators who produce low-gravity crude oil. Rod floating, overloaded pumping units, and pumps plugged with heavy crude oil are common occurrences. Likewise, such problems as stuck pumps, eroded tubing and sucker rod couplings, and stripping jobs are common wherever sandy production occurs. We experienced all these problems in producing the Brooks reservoir, located in the Cat Canyon field, Santa Barbara County, CA, where oil gravity averages 6°API (1.029 g/cm3), and the production contains up to 70% sand. Over a 5-year period these problems were ameliorated with the development and successful application of special downhole pumping equipment. This paper up-dates a previous work on this topic.1 The Brooks reservoir sand is an unconsolidated basal member of the Pliocene Sisquoc formation. The sand is very fine-grained and well-sorted, with a medium sand-grain size of 0.0065 in (0.165 mm) and a Trask sorting coefficient of 1.2. Reservoir depth ranges from 2,500 to 3,500 ft (760 to 1070 m); average net sand thickness is 150 ft (46 m). A type log is shown in Fig. 1. There is no significant primary water production, and the zone produces at less than 1 to 2 % water cut, except where wateror steam injection has occurred. The oil gravity of Brooks zone is among the lowest produced in the world, and ranges from 11 °API (0.993 g/cm3) in the upstructure area to about 0°API (1.076 g/cm3) downstructure at the reservoir limits. Reservoir oil currently averages about 6°API (1.029 g/cm3) and has 15,000-cp (15-Pa·s) viscosity at reservoir conditions. Reservoir properties of the Brooks sand and fluids are summarized in Table 1. Operating Experience With Conventional Equipment Production from the Brooks zone began in 1909 in the area where highest oil gravity occurs. These early wells were completed with 250-mesh [0.25-in. (6.35-mm)] slots or 1/2-in. (12.7-mm) holes through the zone, which allowed almost unrestrained sand production from the unconsolidated formation. Initially, these wells flowed up to400 B/D (64 m3/d) of 10°API (1.0 g/cm3) oil containing about 15 % sand. Cumulative recovery from this old part of the field is now more than 10% of the OOIP. Individual wells have produced over 400,000 bbl (64 000 m3) of oil and 40,000 bbl (6400 m3) of sand over a 40-year life. To pump the highly viscous oil with conventional pumping equipment it was necessary to inject a distillate into the wellbore, which blended the native oil up to about 12°API (0.968 g/cm3).